University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Environmental -> soil

Citations 221

"Aluminum Speciation In Seasonally Dry High Country Soils, South Island, New Zealand"
Aust. J. Soil Res. 1999 Volume 37, Issue 5 Pages 1005-1015
M. L. Adams, P. D. McIntosh, R. D. Patterson, K. J. Powell

Abstract: Soil solutions from an altitude sequence of South Canterbury high country soils (730-1190 m) were analyzed using a recently developed technique to obtain values for free Al ([Al3+]+[Al(OH)(2+)]+[Al(OH)(2+)]+[Al-F2+]), an organic-bound Al fraction, and the Al-complexation capacity (Al-CC). From 1979 these soils have been fertilised, oversown, and grazed. Since 1978, topsoils (0-7.5 cm) have become more acid, and average pH((H2O)) (1 : 2.5 soil : H2O; n = 38) has fallen from 5.79 in 1978 to 5.25 in 1996. Despite this soil acidification, the current free Al values are low (0.31-0.75 µM) and are unlikely to limit legume growth. This conclusion was supported by root elongation experiments using Medicago sativa (Wairau lucerne). No significant correlation was observed between measured root elongation and either soil solution pH or free Al. Sunny aspects had higher organic-bound Al and lower free Al values. The values of p[Al3+] calculated from free Al were consistent with control of [Al3+] by an Al(OH)(3)(s) phase rather than by organic matter. Organic-bound Al correlated strongly with the concentration of humic substances in soil solution as estimated by the UV absorbance at 250 nm. The Al-CC decreased with a decrease in soil solution pH. Relative to the total reactive Al, the capacity of soil solutions to complex Al, as may be generated by acidification, was lower for the soils at lower elevations, pointing to potential for an earlier onset of Al toxicity at these sites.
Ionic strength Speciation

"Problems Of Selenium Fractionation In Soils Rich In Organic Matter"
Anal. Chim. Acta 2000 Volume 408, Issue 1-2 Pages 103-109
M. Bujdoš, J. Kubová and V. Streško

Abstract: Hydride generation atomic absorption spectrometry (HGAAS) was used for the determination of Se in soils. Potential interferences from metal ions and spectral interference in the heated quartz tube were documented and eliminated. The efficiency of four acid-based closed vessel decomposition procedures was checked with certified reference soils and a pressured microwave sample preparation using (1 + 1) HNO3 : H2SO4 was recommended for the determination of total Se components in soils. The effect of a high content of organic matter on the reliable determination of Se was examined and eliminated. A sequential extraction procedure was developed for the determination of the speciation of Se in a forest soil profile. The detection Limit for the total Se determination was 6 ng Se/g soil, and the relative standard deviations were <5% after application of the sequential extraction procedure. The proposed method was applied to a red forest soil sample and the vertical distribution of Se species in the soil profile was investigated and evaluated.
Selenium, total Spectrophotometry Sample preparation Speciation Reference material

"Design Of A Very Versatile Software Program For Automating Analytical Methods"
Lab. Rob. Autom. 1999 Volume 11, Issue 3 Pages 131-140
E. Becerra, A. Cladera, V. Cerd&agrave;

Abstract: The present article proposes the design of a hardware-independent system for automating various analytical methods. System design is based on the division of the software into four layers, defining a communications interface among them. The definition of these layers allows the isolation of the highest, corresponding to the analytical application, from the lowest, the hardware, composed of the various parts of the block diagram. Although this system was initially designed for automating pow techniques (flow injection analysis, FIA, and sequential injection analysis, SIA), its conception allows the development of much more general applications, depending on the users imagination. The system is very open, in the sense thatit is not necessary to adapt the program as system possibility ties are expanded. Thus, if new instrumentation (modules in the block diagram) is incorporated, one need only develop independently a minimum of software to comply with the previously defined interface. This system has been developed under the 32-bit Windows 95 environment, making the exchange of information with other applications very simple and allowing the various possibilities offered by the program to be executed simultaneously (for example, data acquisition and processing).
Automation Computer

"Atomic Fluorescence Determination Of Inorganic Arsenic In Soils After Microwave-assisted Distillation"
Anal. Chim. Acta 2000 Volume 407, Issue 1-2 Pages 155-163
Cristina Maria Barra, M. Luisa Cervera, Miguel de la Guardia and Ricardo Erthal Santelli

Abstract: An inexpensive microwave-assisted distillation procedure has been developed for quantitative determination of inorganic arsenic in soils by atomic fluorescence spectrometry (AFS). After reduction of As(V) to its trivalent state with potassium iodide, inorganic arsenic was distilled as AsCl3 that was finally determined by atomic fluorescence after hydride generation with NaBH4 in HCl medium. The different parameters that control the distillation: concentration and volume of HCl, time of distillation, sample weight, and oven load, win studied. The methodology developed has a detection limit of 0.015 µg L-1 which corresponds to a concentration of 0.006 µg of As per gram of soil, and a relative standard deviation of 3% for nine independent analyzes of the same soil sample containing 8.7 µg g-1 As. The recovery percentage of As(III) and As(V) were 103±4 and 106±4%, respectively, Total arsenic was determined after microwave-assisted digestion, under pressure, with HCl : HNO3 (3 : 1)/H2O2 in hermetically sealed Teflon reactors. By introducing an additional microwave-assisted digestion step after distillation of inorganic arsenic, the organic fraction of arsenic in soils and sediments was established.
Arsenic(3+) Arsenic(5+) Arsenic, inorganic Fluorescence Sample preparation Volatile generation Speciation

"Evaluation And Characteristics Of A Pb(II) Ion-selective Electrode Based On Aquatic Humic Substances"
Anal. Chim. Acta 2000 Volume 418, Issue 2 Pages 205-212
Xiaoqiao Lu, Zuliang Chen, Simon B. Hall and Xinhao Yang

Abstract: An ion-selective poly(vinyl chloride) PVC membrane electrode based on humic substances (HSs) isolated from swamp water was developed for the detection of Pb(II) in aqueous solutions. The electrode exhibited a nearly theoretical Nernstian slope of 28.6 mV per decade in the range of Pb(II) concentrations from log(10)(a(Pb(II))) -5.5 to -2.2 with a detection limit of log(10)(a(Pb(II)))=-5.7 in the steady-state mode. The electrode showed good sensitivity, selectivity, and rapid response for Pb(II) in acidic solution (pH=4.50). The interference study of some alkali, alkaline, and heavy metal ions showed that these metal ions did not exhibit interference on the ion-selective electrode (ISE) in its detection of Pb(II) under the conditions employed in this study. The electrode was used to determine Pb(II) in synthetic soil samples by flow injection potentiometric analysis. The investigation into the interaction between HSs and Pb(II) using fluorescence spectroscopy showed that complexation of Pb(II)) by the HSs results in the potential response of this electrode.
Lead(2+) Potentiometry Electrode Electrode Detector Complexation Interferences

"Flow Injection Analysis. 7. Use Of Ion-selective Electrodes For Rapid Analysis Of Soil Extracts And Blood Serum. Determination Of Potassium, Sodium And Nitrate"
Anal. Chim. Acta 1977 Volume 88, Issue 1 Pages 1-16
J. Ruzicka, E. H. Hansen and E. A. Zagatto

Abstract: The flow injection principle is used with novel design of a flow cell, in which the ion-selective an reference electrode are incorporated. The reproducible mixing of the sample with the carrier stream of electrolyte and the precise timing of potentiometric measurements in the continuously moving stream are the most important parameters influencing the quality of direct potentiometric measurements. Methods for the determination of NO3- and K in soil extracts, and Na and K in blood serum are described. At sampling rates of 125 determinations per hour, a standard deviation of only 0.8% is typical. Simultaneous measurements of two ions on one stream are described; advantages and drawbacks of the use of ion-selective electrodes in continuous-flow measurements are discussed; and the new possibilities which the flow injection method offers are contemplated.
Nitrate Potassium Sodium Clinical analysis Electrode Electrode Electrode Sample preparation Flowcell Apparatus Dual detection

"Flow Injection Analysis Of Calcium In Serum, Water And Waste Water By Spectrophotometry And By Ion-selective Electrode"
Anal. Chim. Acta 1978 Volume 100, Issue 1 Pages 151-165
E. H. Hansen, J. Rika and Animesh K. Ghose

Abstract: The flow injection technique is a fast, reliable, and sensitive method for the determination of Ca in various aqueous as well as serum samples; spectrophotometric or potentiometric detection can be used. At sampling rates of 100-10 samples/h, with 30 µL sample injections, high reproducibility of measurement and low reagent consumption are achieved in both methods. In the spectrophotometric method (with o-cresolphthalein complexon), the anal. readout is available within 12 s after sample injection at a total reagent consumption of 0.75 mL/anal. The potentiometric measurement of the Ca activity in serum is placed on a reliable basis by alternating measurements of serum samples and aqueous standards without incurring any nonreproducible changes in potential between aqueous and serum solutions This permits the simultaneous determination of pH and pCa, the anal. readout being available within 3 s of sample injection. The good agreement between the results obtained with the flow injection method and those attained by atomic absorption and EDTA titrns. as well as pCa stat-measurements show that the new methods are potentially suitable for routine anal.
Calcium pH Spectrophotometry Electrode Potentiometry Method comparison

"Solvent Extraction In Continuous-flow Analysis. Determination Of Molybdenum In Plant Material"
Anal. Chim. Acta 1978 Volume 101, Issue 1 Pages 9-16
H. Bergamin F&deg;, J. X. Medeiros, B. F. Reis and E. A. G. Zagatto

Abstract: A method is proposed for solvent extraction in continuous-flow injection analysis. Optimal tube lengths, pumping extraction efficiency, sample volumes, etc. are discussed. The thiocyanate method for the determination of molybdenum in plant material is used to demonstrate the feasibility of the method. A phase-separation chamber and a proportional injector are described. The proposed method can be used to determine molybdenum in plant ash solutions down to 0.05 ppm with good reproducibility and accuracy, at a rate of ~30 samples/h.
Molybdenum Molybdate Spectrophotometry Sample preparation Sample preparation Optimization Phase separator Preconcentration Proportional injector Solvent extraction

"Merging Zones In Flow Injection Analysis. 3. Spectrophotometric Determination Of Aluminum In Plant And Soil Materials With Sequential Addition Of Pulsed Reagents"
Anal. Chim. Acta 1979 Volume 107, Issue 1 Pages 309-317
B. F. Reis, H. Bergamin F&deg;, E. A. G. Zagatto and F. J. Krug

Abstract: A flow injection procedure is described for the spectrophotometric determination of Al in plant and soil material with eriochrome cyanine R [3564-18-9]. This system uses merging zones and sequential addition of pulsed reagents. A high degree of sample dispersion and pulsed neutralization reagent allowed precise pH control; acid plant digests could therefore be analyzed without pretreatment. Fe(III) interference was avoided with ascorbic acid, and phosphate interference was negligible. The sampling rate was 120 samples/h, reproducibility was better than 1% for a 5.0 ppm Al standard and the calibration plot was linear in the range 0-20 ppm Al. Applied to soil and plant samples, the method gave recoveries of 98-101%.
Aluminum Spectrophotometry Intermittent pumping Pulsed reagent Merging zones Interferences

"Simultaneous Determination Of Nitrate And Nitrite By Flow Injection Analysis"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 191-197
M. F. Gin&eacute;, H. Bergamin F, E. A. G. Zagatto and B. F. Reis

Abstract: An automatic method for the simultaneous determination of NO3- and NO2- by flow injection analysis is described. NO3- is reduced to NO2- with a copperized Cd column. NO2- is diazotized and coupled with N-(1-naphthyl)ethylenediammonium dichloride. A spectrophotometric detector is used. The merging zones approach is used to minimize reagent consumption. The injector system is arranged so that 2 peaks are obtained, 1 corresponding to NO2- and the other to NO2-+NO3-. A sampling rate of ~90 samples/h is possible; the precision is better than 0.5% for NO2- in the range 0.1-0.5 mg L-1 and 1.5% for NO3- in the range 1.0-5.0 mg L-1. The method was used to analyze soil and water samples.
Nitrate Nitrite Spectrophotometry Reduction column Merging zones Multielement Proportional injector

"Determination Of Iron(II) And Iron(III) By Flow Injection And Amperometric Detection With A Glassy Carbon Electrodes"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 267-274
J. W. Dieker and W. E. Van Der Linden

Abstract: Flow injection analysis can be used for the determination of both Fe(II) and Fe(III) with an amperometric detector. The flow-through cell contains a glassy C electrode. Selection of the appropriate voltammetric technique choice of the indication potentials, sample size, composition of the carrier stream, etc., are discussed. The limit of determination is ~10-6M; the calibration curves are linear in the concentration. ranges 10^-3-10-5 M for Fe(III) and 5 x 10^-4-10-5 M for Fe(II). To illustrate the potentialities of the proposed method, standard rocks have been analyzed.
Iron(2+) Iron(III) Amperometry Electrode Speciation Optimization Reference material

"Continuous-flow, Isotope-dilution Method For Studies Of Adsorption Behaviour Of Metal Ions"
Anal. Chim. Acta 1980 Volume 116, Issue 2 Pages 275-287
E. Hartmann, K. Randle

Abstract: A method is described for studying adsorption from liquids based on a continuous-Flow system. The major innovation is the use of radioisotope dilution to determine the change in the eluate concentration. The metal under study is radioactively labelled and the activity of the eluate leaving the cell is monitored with a well-shielded NaI(Tl) detector. From the known flow rate and initial activity, the activity of the eluate can be related to the adsorbate concentration. The counts accumulated over a set period of time are automatically stored in successive memory locations of a computer. These data are also displayed, allowing continuous monitoring of the developing wash-in curve as well as on-line data manipulation. Modifications to the ultrafiltration cell used and to the method of pumping solutions through the cell are described. The method is worked out for the mercury-humic acid system via 203Hg; applications to other systems are indicated.
Metals Mercury Mass spectrometry

"Merging Zones In Flow Injection Analysis. 6. Determination Of Calcium In Natural Waters, Soil And Plant Materials With Glyoxal-bis(2-hydroxanil)"
Anal. Chim. Acta 1981 Volume 130, Issue 2 Pages 361-368
A. O. Jacintho, E. A. G. Zagatto, B. F. Reis, L. C. R. Pessenda and F. J. Krug

Abstract: A flow injection procedure is proposed for the spectrophotometric determination of calcium in natural waters, soil extracts and plant digests, employing glyoxal bis(2-hydroxyanil) as the color-forming reagent. The necessary dissociation of this reagent, which is rather slow, proceeds outside the analytical path, and the merging-zones approach is used for reagent addition. Composition of reagents, dissociation time of the colorforming reagent, ethanol content in the carrier streams and interferences are described. In the analysis of plant and soil materials, zone sampling is required for initial sample dilution. The proposed systems are very stable and permit a sampling rate of 180 determinations per hour. Relative standard deviations are less than 1%. The results compare well with those obtained by inductively-coupled argon-plasma atomic emission spectrometry.
Calcium Spectrophotometry Apparatus Injector Zone sampling Merging zones

"Evaluation Of Critical Parameters For Measurement Of PH By Flow Injection Analysis. Determination Of PH In Soil Extracts"
Anal. Chim. Acta 1985 Volume 169, Issue 1 Pages 209-220
Cui Hongbo, E. H. Hansen and J. Rka

Abstract: The parameters affecting pH measurements in a flow injection system incorporating a tubular PVC-based pH-sensitive membrane electrode have been evaluated. A dispersion coefficient, Dmax, of 1.008 at peak maximum is required and the buffering capacity of the carrier stream must be less than that of the sample solution. Suitable system designs are discussed. Examples are presented of the determination of pH in 16 soil extracts; the results agreed with those obtained by conventional glass electrode measurements.
pH Electrode Electrode Potentiometry Sample preparation Dispersion Method comparison Theory

"Potential Of The Flow Injection Technique In Soil Chemical Analysis"
Anal. Chim. Acta 1986 Volume 180, Issue 1-3 Pages 8-11
Zhaolun Fang

Abstract: Since its introduction into soil chemical studies at the Institute of Forestry and Soil Science, Academia Sinica, in about 1977, flow injection (FI) analysis has gradually gained acceptance as one of the most efficient and versatile techniques ever introduced. More than twenty well-established yet sometimes tedious manual methods have been replaced by automated FI procedures. These form the basis of a fully automated soil analysis system. For the most frequently determined fractions, such as total nitrogen and phosphorus in soils, adoption of FI techniques has increased sample throughput three to four-fold without increasing the number of technical personnel needed. FI procedures have generally proved more precise and reliable than their manual counterparts and reagent consumption is also considerably lower. Trace element analyzes of soils can be done efficiently and accurately by FI analysis even in the absence of an atomic absorption spectrometer. Various satisfactory attempts have been made at combining FI analysis with flame AAS.
Spectrophotometry Review Reagent consumption

"Flow Injection Catalytic Determination Of Molybdenum With Biamperometric Detection In A Microprocessor-controlled System"
Anal. Chim. Acta 1986 Volume 188, Issue 1 Pages 165-175
M. Trojanowicz, A. Hulanicki, W. Matuszewski and M. Pays, A. Fuksiewicz, T. Hulanicka-Michalak, S. Raszewski and J. Szyller, W. Augustynlak

Abstract: The flow injection determination of Mo(VI) is based on its catalytic effect on the oxidation of I- by 6 mM H2O2 (in 0.1 M H2SO4). The I3- produced is detected amperometrically in a flow-through cell containing two platinum-wire electrodes polarized at 100 mV. A microprocessor-controlled processing system is described. Optimum conditions include a flow rate of 2.4 mL min-1 in each channel and a sample volume of 250 µL. A sampling rate of 100 h-1 is possible. The detection limit is 1.2 µg L-1 of Mo(VI) and response is rectilinear to 1 mg l-1. The interference of W(VI), V(V), Cr(VI), Mn(II), Cu(II) and Fe(III) is studied, and the use of masking agents is discussed. The method is applied in the determination of Mo(VI) in soil extracts.
Molybdenum(VI) Biamperometry Electrode Sample preparation Catalysis Computer Interferences

"Flow Injection Determination Of Nitrite And Nitrate With Biamperometric Detection At Two Platinum Wire Electrodes"
Anal. Chim. Acta 1987 Volume 194, Issue 1 Pages 119-127
A. Hulanicki, W. Matuszewski and M. Trojanowicz

Abstract: Nitrite and NO3- were determined in a flow injection system with a carrier solution (2.4 mL min-1) of 0.1 M H2SO4 and 0.2 M KI. The amperometric detector consisted of a flow cell containing two platinum or PTFE-coated graphite electrodes (8 mm x 0.3 mm) maintained at a constant polarizing voltage of 100 mV. Rectilinear calibrations were achieved over the range 2 to 30 µM with a detection limit of 0.4 µM for each analyte. Nitrate was determined by the inclusion in the flow system of an 8-cm glass column packed with cadmium granules which had been activated by treatment with 0.1 M CuSO4. A carrier solution containing 1% of NH4Cl or (NH4)2SO4 was used through the reductor and EDTA was added to the other carrier to suppress cation interferences. Determination of NO3- in aqueous soil extracts gave similar results to those obtained by potentiometric determination with a NO3--selective electrode.
Nitrate Nitrite Amperometry Electrode Electrode Electrode Electrode Sample preparation Potentiometry Interferences Method comparison

"Determination Of Bismuth, Cadmium And Lead In Soil By Atomic Absorption Spectrometry With Loop Sample Introduction"
Anal. Chim. Acta 1987 Volume 196, Issue 1 Pages 277-282
S. G&uuml;cer and M. Demir

Abstract: Bismuth, cadmium and lead in soil extracts with aqua regia, 2 M nitric acid, 2.5% acetic acid or ammonium acetate solution from top-soils at different locations in Turkey, were determined by atomic absorption spectrometry with loop sample introduction. Detection limits were 0.8, 0.025 and 0.5 µL-1 for bismuth, cadmium and lead, respectively, after concentration with ammonium pyrrolidinedithiocarbamate. Use of a silica tube for atom trapping improved the detection limits.
Bismuth Cadmium Lead Sample preparation Spectrophotometry

"Multi-ion Sensor Cell And Data-acquisition System For Flow Injection Analysis"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 359-366
T. J. Cardwell, R. W. Cattrall and P. C. Hauser, I. C. Hamilton

Abstract: The flow injection system comprised a miniature flow cell (illustrated) with several solid-contact electrodes, a differential amplifier and a computer-controlled data-acquisition unit. Ion-selective membrane electrodes containing valinomycin, neutral carrier ETH 1001 and tetradodecylammonium nitrate were used for determination of K, Ca and NO3-, respectively, and a Ag - AgCl electrode was used for determining Cl-. The data-acquisition system is described in detail. The system was tested for the analysis of soil solution by using 0.1 M Na acetate containing 10 µM-KNO3 and 10 µM-CaCl2 as carrier stream (1 mL min-1). Calibration graphs were rectilinear over the range 0.1 mM to ~0.1 M for all four ions. Results agreed with those obtained by automated flow injection AAS and ion chromatography.
Potassium Calcium Nitrate Chloride Electrode Electrode Electrode Electrode Sample preparation Sensor Method comparison Simultaneous analysis

"Direct Spectrophotometric Determination Of Total Boron In Soils With Ultrasonic Leaching In Automatic Flow Systems"
Anal. Chim. Acta 1989 Volume 222, Issue 2 Pages 221-227
Danhua Chen, F. L&aacute;zaro, M. D. Luque De Castro and M. Valc&aacute;rel

Abstract: Sample (5 to 10 mg) was leached for 0.5 min in 0.1 M HCl at 80°C with ultrasonic agitation. The solution was injected into a flow of 0.1 M HCl (0.36 mL min-1) which merged with previously mixed aqueous azomethine-H (7.5 mg mL-1) and EDTA - H3PO4 - aqueous NH3 buffer solution (pH 7.35) each flowing at 0.18 mL min-1. The mixture passed through a reaction coil (440 cm x 0.7 mm) and the absorbance was measured at 416 nm. The calibration graph was rectilinear for 0.2 to 2.5 µg mL-1, and the mid-range coefficient of variation (n = 5) was 2.6%. The sampling rate was 25 h-1.
Boron Sample preparation Spectrophotometry Automation Buffer

"Flow Injection Extraction-spectrophotometric Method For The Determination Of Lead And Its Combination With Minicolumn Preconcentration"
Anal. Chim. Acta 1990 Volume 230, Issue 1 Pages 157-162
E. A. Novikov, L. K. Shpigun and Yu. A. Zolotov

Abstract: Two flow injection systems were devised, one without and one with ion-exchange pre-concentration. [2-mm-i.d. glass column of Chelex-100 resin (NH4+ form; 50 to 100 mesh)]. The Pb(II) was extracted from an aqueous HNO3 carrier stream into dicyclohexano-18-crown-6 solution in CHCl3 in a PTFE coil (2 m x 0.5 mm), and after phase separation in a membrane separator the CHCl3 layer was treated with 0.002% dithizone - 0.4% triethanolamine solution in CHCl3 (mixing ratio 3:2) in a 30-cm PTFE reaction coil for absorbance measurement at 512 nm. With ion-exchange pre-concentration. for 79 s, the calibration graph was rectilinear in the range 10 to 200 µg l-1, the detection limit was 5 µg L-1 and the coefficient of variation at 100 µg L-1 was 9% (n = 4). Test applications to analyzes of alloys, soil extracts and seawater are described briefly.
Lead Ion exchange Spectrophotometry Sample preparation Chelex Chelation Resin Crown ether Extraction Column Preconcentration Phase separator Membrane Calibration Detection limit Organic phase detection Dithizone

"Spectrofluorimetric Determination Of Diquat By Manual And Flow Injection Methods"
Anal. Chim. Acta 1991 Volume 244, Issue 1 Pages 99-104
T. P&eacute;rez-Ruiz, C. Mart&iacute;nez-Lozano and V. Tom&aacute;s

Abstract: In the manual method, sample solution, containing 0.03 to 9 µg of diquat (I), was mixed with 2 mL of 0.5 M borax buffer (pH 8), 1 mL of 0.5% sodium dithionite and water to 10 mL and, after 5 min, the resulting stable radical of I was detected fluorimetrically at 497 nm (excitation at 428 nm). The method was also adapted for use in a flow injection procedure (diagram of apparatus and details given. The calibration graph was rectilinear from 3 to 900 and 18 to 4000 µg L-1 of I by the manual and flow injection methods, respectively; the detection limit by the manual method was 0.4 µg L-1 and coefficient of variation were 2%. The method was applied in the determination of I in commercial herbicide formulations, water, potatoes, flowers and soil (sample prep. described) and in serum and urine directly with use of a standard additions method.
Diquat Fluorescence Buffer Standard additions calibration

"Flow Injection Analysis For Aluminum With Indirect Amperometric Detection"
Anal. Chim. Acta 1992 Volume 256, Issue 1 Pages 117-123
Alison J. Downard, H. Kipton J. Powell* and Shuanghua Xu

Abstract: An Al(III) sample (25 µL) was injected into a carrier stream of water which was then mixed with 1,2-dihydroxyanthraquinone-3-sulfonic acid (I) in 0.5 M ammonium acetate - ammonia buffer (pH 9.0) and passed to a flow cell. The excess I was measured amperometrically at 0.50 V on a gold electrode, against a Ag/AgCl reference electrode (electrolyte 0.1 M KCl). Fouling of the electrode by adsorption of I oxidation products was minimized by use of a double pumping system to provide reagent and wash cycles. The rectilinear working range depended on the I concentration. The detection limit when using 0.02 mM I was 0.25 µM Al and the coefficient of variation for 9 µM Al was 4.3% (n = 6). Nitrilotriacetic acid, tannins and Fe(III) interfered. The method was applied to the determination of Al(III) in soil extracts. Aluminum was determined in a flow injection system involving the formation of the aluminum(III)-1,2-dihydroxyanthraquinone-3-sulfonic acid (DASA) complex at pH 9.0 and amperometric measurement of excess of DASA at +0.50 V on a gold electrode. Electrode fouling by adsorption of DASA oxidation products was minimized by use of a double pumping system to provide a reagent cycle and a wash cycle. During the wash cycle the gold electrode surface was reactivated electrochemically by cathodic-anodic voltage cycling. The linear working range was governed by the DASA concentration. For 2 x 10^-5, 5 x 10^-5 and 5 x 10^-4 M DASA the linear ranges were (0.05-1.0) x 10^-5, (0.1-2.2) x 10^-5 and (0.1-1.2) x 10^-4 M Al(III), respectively. The detection limit when using 2 x 10^-5 M DASA was 2.5 x 10^-7 M Al(III) and the RSD for 9 x 10^-6 M Al(III) was 4.3% (n = 6). Nitrilotriacetic acid, tannins and Fe(III) interfered; no interference was observed with F-, PO43-, citric, oxalic and fulvic acids, Mg2+ or Ca2+. The method was applied to the determination of Al(III) in soil extracts.
Aluminum(III) Amperometry Electrode Sample preparation Indirect Interferences

"Determination Of Total Soil And Plant Nitrogen Using A Micro-distillation Unit In A Continuous-flow Analyser"
Anal. Chim. Acta 1992 Volume 266, Issue 1 Pages 113-117
S. McLeod*

Abstract: Soil and plant samples were digested as described earlier ('Notes on Soil Techniques', Vol. 4, Division of Soils, CSIRO, 1982, p. 27) and the digests were analyzed by using a manifold incorporating the distillation unit already described (see preceding abstract). The salicylate - nitroprusside - dichloroisocyanurate reaction system (cf. Pym and Milham, Anal. Chem., 1976, 48, 1413) was used under optimized conditions of reagent concentration. and pH. For soils containing ~0.5 to 5.4 g kg-1 of N, the coefficient of variation ranged from 0.8 to 10.5%. A procedure for the automated determination of soil and plant N from Kjeldahl digests was proposed. The continuous-flow system involved the use of a unique micro-distillation unit followed by colorimetric detection of the pure NH4Cl distillate. Optimization of the indophenol reaction is shown together with a standard manual procedure for comparison. Interference-free determinations may be carried out at a min. of 30 samples h-1 and the system has proved to be most reliable for routine analysis.
Nitrogen, total Sample preparation Spectrophotometry Interferences Optimization pH Kjeldahl

"Micro-distillation Unit For Use In Continuous-flow Analysers. Its Construction And Use In Determination Of Ammonia And Nitrate In Soils"
Anal. Chim. Acta 1992 Volume 266, Issue 1 Pages 107-112
S. McLeod*

Abstract: The unit described and illustrated is constructed from stainless steel and fits into an Al heating block; two such stills have been incorporated into parallel continuous-flow systems for the determination of NO3- plus NH4+ and of NH4+ alone in 2 M KCl extracts of soil by the indophenol reaction. In the former system, the extract is mixed with Ti2(SO4)3 as reductant before the distillation. Optimized conditions for the analyzes were established. The coefficient of variation for standards run for every 30 samples were 5%. The calibration graph for NH4+-N was rectilinear up to 10 mg l-1.
Ammonia Nitrate Sample preparation Spectrophotometry Apparatus Optimization Heated reaction

"Determination Of Arsenic And Selenium In Environmental Samples By Flow Injection Hydride-generation Atomic Absorption Spectrometry"
Anal. Chim. Acta 1992 Volume 270, Issue 1 Pages 231-238
Chris C. Y. Chan* and Ram S. Sadana

Abstract: Environmental samples such as soil, vegetation, water, sediments and industrial wastes were digested (except for water) by heating at 200°C with HNO3 - H2SO4 - HClO4 (6:3:1). The cooled digest or water was treated with concentrated HCl to reduce Se6+ to Se4+; for As analysis the solution was treated with 10% KI - 1% ascorbic acid (10:1) to reduce As5+ to As3+. The analytes were converted to the hydrides with 1% NaBH4 in an automated hydride-generation system. A stream of Ar (3 mL min-1) carried the evolved hydride via a gas - liquid separator and an impinger to a heated quartz tube atomizer for analysis by AAS. The effects of the experimental variables are discussed. Interference by Cu and Ni on the determination of Se was masked with 1,10-phenanthroline. The detection limits for both As and Se were 0.3 ng mL-1. The coefficient of variation was 2.6% for As in a sediment (n = 10) and 2% in water (n = 5); similar precision was obtained for Se. The results for the standard reference materials agreed closely with their certified values. Flow injection analysis is applied to sample introduction in conjunction with automated hydride generation and AAS for the determination of As and Se in environmental samples such as soil, vegetation, waters, sediments, and industrial wastes. A large sample loop was used to provide high sensitivities with an absorbance of 0.4 for 10 ng mL-1 for both As and Se. The samples, except waters, are digested with a mixture of nitric, sulfuric, and perchloric acids. Se6+ in the digested solutions is pre-reduced to Se4+ by exothermic reaction in 6-8 M HCl solution, and As5+ to As3+ by reacting with KI. The analyte is then converted to hydride by NaBH4 in an automated hydride generation system. The evolved hydride is carried through to a heated quartz tube by a stream of argon, and the atomic absorption of the analyte is measured. 1,10-Phenanthroline is used as masking agent to control interferences from Cu and Ni on Se. The detection limits for both As and Se are 0.3 ng mL-1, equivalent to 75 ng g-1 in solid sample. Precision is 2.6% RSD Results for standard reference materials agree closely with the certified values.
Arsenic Selenium Spectrophotometry Reference material Interferences Volatile generation Volatile generation

"Automatic Continuous-flow Determination Of Paraquat At The Sub-nanogram Per Millilitre Level"
Anal. Chim. Acta 1993 Volume 281, Issue 1 Pages 103-109
Manuel Agudo, Angel R&iacute;os and Miguel Valc&aacute;rcel*

Abstract: A water sample (I 0.05 M in NaNO3) pumped at 4 ml/min was mixed with 1% dithionite reagent of pH 12.5 pumped at 2.5 ml/min in a 30 cm-long coil and the mixture was passed to a flow cell containing Dowex 50W-X8-200 (ammonium form). The blue complex bound to the resin was monitored at 605 nm, then the sample stream was changed to an elution solution of ammonium chloride using a switching valve. The calibration graphs depended on the sample volume used; 1 mL gave a linear graph up to 0.2 µg/ml of paraquat with an RSD of 4.6% at a sampling frequency of 10/h, whereas 250 mL gave a linear graph from 0.4-5.5 ng/ml with an RSD of 7.9% and a sampling frequency of 0.9/h. At a volume of 250 mL the detection limit was 0.11 ng/ml. Interference studies showed that other pesticides were tolerated at a ratio of 100:1 except for diquat where this value was 10:1. The method was applied to the determination of paraquat in natural and tap waters and in studies of the adsorption of the herbicide by different soils.
Paraquat Dowex Resin Interferences

"Screening Method For Trace Mercury Analysis Using Flow Injection With Urease Inhibition And Fluorescence Detection"
Anal. Chim. Acta 1994 Volume 292, Issue 1 Pages 185-190
D. Narinesingh*, R. Mungal and T. T. Ngo

Abstract: The method is based on the inhibitory effect of Hg(II) on the enzymatic reaction between urease and urea. Sample (90 µL) was injected into a phosphate-buffered urease (0.25 mg/ml of urease) pH 7 carrier stream (0.3 ml/min) and mixed successively with 10 mM urea (0.3 ml/min; pH 7) and 0.25 M NaOH (0.6 ml/min) reagent streams. The reaction mixture was passed through a gas-separation unit wherein the enzymatically-generated NH3 diffused through a PTFE membrane and was collected in a stream of o-phthaldehyde (I) and mercaptoethanol in borate buffer solution of pH 10.2 and the resulting I-NH3 adduct was determined fluorimetrically at 455 nm (excitation at 340 nm). The calibration graph was linear from 2-22 ppb. The method was used to determine Hg in soil extracts and the results agreed well with those obtained by cold vapor AAS. The sampling rate was 40 samples/h. The method can also be used to determine Ag(I) in the range 0.1-1 ppb.
Mercury Silver Fluorescence Sample preparation Teflon membrane

"Direct Determination Of Ammonium In Solid Samples By Automatic Flow Procedures"
Anal. Chim. Acta 1994 Volume 293, Issue 1-2 Pages 163-170
Zheng-liang Zhi, Angel R&iacute;os and Miguel Valc&aacute;rcel*

Abstract: Two manifolds (A and B) are described. For A, the solid sample was suspended in 2.5 M-NaOH, transferred to the flow system and heated to 100°C in air. The released NH3 was collected in 1.5 mL of 2% boric acid. At the end of the extraction period, the boric acid solution was injected into a 2% boric acid carrier stream (1.2 ml/min) which was merged with a Nessler's reagent stream (0.4 ml/min). The absorbance was measured at 400 nm. The calibration graph was linear for 0.4-10 µg/ml ammonium-nitrogen. The RSD (n = 10) for 1 and 3 µg/ml ammonium-nitrogen were 4.9 and 3.3%, respectively. Recoveries of 6 µM-ammonium-nitrogen were 95-105%. The method was applied to soil (details given). For B, a flow-through gas diffusion probe was inserted into the 0.32 M NaOH suspension. The flow of acceptor stream (2% boric acid) through the probe was stopped during the collection period. At the end of the collection period, the acceptor stream (0.8 ml/min) was merged with a Nessler's reagent stream (0.4 ml/min) and the absorbance at 400 nm was measured. The calibration graph was linear for 0.5-10 µg/ml and the RSD (n = 10) for 3 µg/ml ammonium-nitrogen was 4.3%.
Ammonium Spectrophotometry Gas diffusion

"Direct Determination Of The Cation-exchange Capacity Of Soils With Automatic Sample Pretreatment In A Flow System"
Anal. Chim. Acta 1994 Volume 298, Issue 3 Pages 387-392
Zheng-liang Zhi*, Angel R&iacute;os and Miguel Valc&aacute;rcel

Abstract: An automatic method for the determination of the cation exchange capacity (CEC) in soils by use of a flown-injection system coupled to an open/closed loop sample pretreatment unit was developed. Cations were displaced from exchange sites on soil colloids by dissolved barium, excess reagent being subsequently removed and the solid retained in a filter cartridge located in the open/closed loop unit. The barium fixed in soil was then exchanged with magnesium(II) by adding magnesium sulphate, which aided to further remove barium as a sulphate precipitate. The clear liquid filtrate in the open/closed loop was finally driven to the loop of the injection valve and inserted into a flow system designed for the spectrophotometric determination of residual magnesium(II) with Eriochrome Black T. CEC values ranging from 6.6 to 20 mmol/100 g air-dried soil were obtained with an average relative standard deviation of ± 2.9%. About 10 samples per hour can be processed in this way.
Cations Sample preparation Extraction

"Kinetic Analysis Of Aluminum Complex Formation With Different Soil Fulvic Acids"
Anal. Chim. Acta 1995 Volume 300, Issue 1-3 Pages 227-236
Brian J. Plankey, Howard H. Patterson* and Christopher S. Cronan

Abstract: A fluorescence technique was used to investigate the complex formation kinetics of aluminum with fulvic acids isolated from different forest soil environments. In the pH range of 2.4-3.6, all of the fulvic acids were found to contain two kinetically distinguishable components, which define two types of average aluminum binding sites. Both of these average sites on all of the fulvic acids conformed to a bidentate chelating binding site kinetic analysis, from which average rate and equilibrium parameters were obtained. Evidence indicated that the difference in reaction rate between the two types of aluminum binding sites on the fulvic acids was due to a steric strain, whereby aluminum was repelled from the slower reacting sites. In comparing this study with a similar kinetic study carried out in acetate buffered solutions, it was found that the presence of buffer changed both the overall mechanism by which aluminum reacted with fulvic acid, and the nature of the sites on fulvic acid that bind aluminum.
Aluminum Fluorescence Kinetic Complexation

"Rapid Determination Of Mercury In Environmental Materials Using Online Microwave Digestion And Atomic-fluorescence Spectrometry"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 364-370
A. Morales-Rubio, Ml. Mena and C. W. McLeod*

Abstract: A 70-300 mg portion of environmental material was dispersed in HNO3/H2O (3:2) to form a slurry. A 400 µL portion of the slurry was injected into a 0.01 M HCl carrier stream (2.5 ml/min) and passed through a digestion coil (4 m x 0.8 mm i.d.) mounted in a microwave oven (20 W). The flow passed through a cooling coil (2 m x 0.8 mm i.d.) at 0°C and a degassing module and was merged with a reductant stream (2.5 ml/min) containing 3% SnCl2 in 15% HCl. After passing through the reduction coil (10 cm x 0.8 mm i.d.), the flow entered the gas-liquid separator. The Hg vapor was swept to the atomic-fluorescence detector with an air stream (600 ml/min) and Hg was determined at 253.7 nm. The calibration graph was linear for 2-10 µg/l Hg, the detection limit was 0.23 µg/l and the RSD (n = 3) were ~e;0.5% within the linear range. The method was validated by analyzing certified reference materials including soil, sewage sludge and lake sediment.
Mercury Fluorescence Sample preparation Reference material Microwave Online digestion Phase separator Slurry

"Microwave-assisted Robotic Method For The Determination Of Trace Metals In Soil"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 371-377
P. Torres, E. Ballesteros and M. D. Luque De Castro*

Abstract: A fully automatic method for the determination of trace metals (Fe, Cu and Zn) in soil was described involving DTPA extraction, online microwave digestion and determination by AAS. The analysis was carried out using a robotic station. Soil (3 g) was transferred to a digestion tube (10 cm x 1.6 mm i.d.) and 6 mL of extractant was added. The extractant contained of 5 mM DPTA, 10 mM CaCl2 and 0.1 M triethanolamine in water of pH 7.3. The tube was sealed and exposed to microwave radiation for 3 min at 20 W. The resulting slurry was centrifuged and the supernatant was aspirated into the AAS following dilution if required. The results were expressed as concentration of metal in the extractant. The calibration graphs for all three analytes were linear for 2.5-50 µg/ml. The RSD (n = 11) for the determination of 20 µg/ml Fe(II) was 1.5%. The sampling frequency was 5 samples/h.
Iron Copper Zinc Sample preparation Spectrophotometry Online digestion Microwave Automation Robot

"Continuous-flow Analysis: Simultaneous Spectrophotometric Determination Of Metals"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 386-396
Yu. A. Zolotov, E. I. Morosanova*, S. V. Zhalovannaya and S. S. Dyukarev

Abstract: Continuous-flow analysis methods for the simultaneous determination of (i) aluminum and manganese, (ii) aluminum and iron(III) and (iii) calcium and magnesium were developed. The methods were based on ligand-exchange reactions or reactions at different rates. For (i) the Al and Mn complexes with xylenol orange (XO) were formed and the combined adsorption was measured at 570 nm in the first detection cell. EDTA was added to the flow system to destroy the Mn-XO complex and allow the Al-XO complex to be determined in the second detection cell at 550 nm. A similar methodology was used for (iii) using eriochrome black T (EB) to determine the combined Ca and Mg concentration at 540 nm. EDTA was added to destroy the Ca-EB complex and allow the Mg-EB complex to be determined also at 540 nm. The different rate of reaction with XO were utilized for (ii). The signal recorded in the first cell at 560 nm was due to the Fe-XO complex while that recorded in the second cell at 550 nm was due to the combined absorption of the Fe-XO and Al-XO complexes. The full details of each method are presented along with the linear ranges and detection limits. The methods were tested on synthetic and real samples (soil extracts, sedimentary rocks). High accuracy and good precision were obtained with RSD of 1-6.5%. The sampling frequency was up to 32 samples/h.
Aluminum Calcium Manganese Magnesium Iron(III) Spectrophotometry Sample preparation Complexation Segmented flow Kinetic

"Flow Injection Analysis Of Paraoxon With The Use Of An Immobilized Acetylcholinesterase Reactor"
Anal. Chim. Acta 1996 Volume 324, Issue 1 Pages 21-27
Renbing Shi and Kathrin Stein*

Abstract: A flow injection procedure for the determination of paraoxon as an example of organophosphorus pesticides based on inhibition of acetylcholinesterase immobilized on the polymer carrier VA Epoxy Biosynth was studied. The detection was carried out spectrophotometrically by means of enzymatic hydrolysis of acetylthiocholine iodide and reaction of the thiocholine from the enzymatic reaction with 5,5'-dithiobis(2-nitrobenzoic acid). Under optimal conditions for an inhibition time of 30 min the calibration graph was linear from 0.05 to 0.5 µg L-1 (r = 0.998, n = 5) with a relative standard deviation of 4.1% at 0. 1 µg l-1. For an inhibition time of 3 min the calibration graph was linear from 2 to 20 µg L-1 with relative standard deviation (n = 3) of 1.2% at 5 µg l-1. The inhibited enzyme was reactivated by 0.01 mol L-1 2-pyridinealdoxime methiodide. The recoveries from the samples to which paraoxon had been added (water, soil) were 104% and 94%, respectively. The determination of paraoxon was based on the inhibition of acetylcholinesterase. The sample solution was pumped (1.32 ml/min) for 3-30 min through an enzyme reactor (45 mm x 2 mm i.d.) packed with acetylcholinesterase immobilized onto polymer carrier VA Epoxy Biosynth. The valves were switched at the end of this inhibition time and a carrier stream of 1 mM Tris/6.64 g/l NaCl/1 g/l MgCl2 of pH 8.3 was passed through the reactor at the same flow rate. To measure the inhibition of the immobilized enzyme, 100 µL of 100 mg/l acetylthiocholine iodide was injected into the carrier stream and the liberated thiocholine was detected spectrophotometrically at 417 nm following reaction with 0.1 g/l 5,5'-dithiobis(2-nitrobenzoic acid) (0.56 ml/min). The enzyme reactor was regenerated with 0.01 M 2-pyridinealdoxime methiodide at 1.32 ml/min for 1.5 min. The calibration graphs for paraoxon were linear for 0.05-0.5 µg/l and 2-20 µg/l for inhibition times of 30 and 3 min, respectively. RSD (n = 3 or 5) were 4.1% (30 min) for 0.1 µg/l paraoxon and 1.2% (3 min) for 5 µg/l paraoxon. The recoveries for 0.1 µg/l paraoxon from spiked pond water and soil were >94% with 30 min inhibition time.
Paraoxon Pesticides, organophosphorus Spectrophotometry Immobilized enzyme Optimization Reactor

"Flow Injection Determination Of Aluminum(III) Ions And Al13O4(OH)24 (H2O)127+ Species Using A 1.3 S Reaction With 8-quinolinol-derivatized Fractogel"
Anal. Chim. Acta 1997 Volume 343, Issue 1-2 Pages 19-32
Stuart L. Simpson, Kipton J. Powell*, and Nils H. S. Nilsson

Abstract: A flow injection spectrophotometric method is described to determine (i) 'free Al', viz. Al3+ plus Al(OH)2+ and very labile Al complexes, (ii) Al in moderate labile complexes and (iii) Al-hydroxo polymers, viz. Al13(OH)327+. A sample volume of 650 µL was inserted into a carrier stream (1 ml/min) of 0.05 M sodium acetate/0.05 M NaCl of pH 5 and propelled through a column reactor (22 µL) containing 8-quinolinol immobilized onto Fractogel. Free Al and Al-hydroxo polymers were retained by the column while moderate labile Al complexes passed through. The column effluent was merged with a reagent stream formed online by merging 2 M acetate buffer of pH 5.3 (0.21 ml/min) and 2 mM chrome azurol S (0.04 ml/min). The flow then passed through a reactor coil (300 cm x 0.5 mm i.d.) to the detection cell (70 µL) where the absorbance was measured at 545 nm. Free Al was eluted from the column reactor with 250 µL 0.02 M NaOH and the Al-hydroxo polymers were eluted with 60 µL 0.2 M NaOH using a 2 min stopped-flow procedure. The linear range of the method was 0.3-16 µM-Al3+, the detection limit was 70 nM and the RSD for 0.5 µM was 7%. The method was applied to aqueous soil extracts and humic waters and the results for free Al were compared to those obtained by the 7 s chrome azurol S method.
Aluminum(III) Aluminum, free Spectrophotometry Sample preparation Speciation 8-Hydroxyquinoline Immobilized reagent Method comparison Stopped-flow Column

"The Aluminum(III)-4-nitrocatechol System: Potentiometry, Voltammetry And Application To The Determination Of Reactive Al(III)"
Anal. Chim. Acta 1997 Volume 345, Issue 1-3 Pages 5-15
A. J. Downard, R. J. Lenihan, S. L. Simpson, B. O'Sullivan and K. J. Powell

Abstract: Four Al(III)-4-nitrocatechol (4ncat) complexes were studied by potentiometry and voltammetry from pH 3-11 and with 4ncat:Al(III) ratios of 1-4. A technique involving amperometric detection was described for determining Al(III) in environmental materials. The method was based on the quantitative formation of [Al(4ncat)3]3- at pH 9. The method was applied to aqueous extracts from soils. An extract (700 µL) was inserted into a carrier stream of acetate buffer of pH 5 at a flow rate of 0.98 ml/min then propelled through an oxine microcolumn (22 µl). The retained Al3+, Al(OH)2+, Al(OH)2+ and labile Al complexes (e.g. AlF2+, AlF2+) were subsequently eluted with 200 µL 0.02 M KOH to form an analyte plug of [Al(OH)4]-. The analyte plug was merged with a reagent stream prepared online from ammonium buffer of pH 9 at a flow rate of 0.36 ml/min and 1.6 mM 4ncat at a flow rate of 0.03 ml/min. Detection was carried out at a glassy carbon electrode at 0.3 V vs. SCE (Pt auxiliary electrode). Calibration graphs were linear from 0.4-8 µM-Al(III); the detection limit was 0.08 µM. RSD were 3.5% and 0.3% for 1 and 10 µM-Al(III), respectively.
Aluminum(III) Amperometry Electrode Voltammetry Potentiometry Sample preparation Column Complexation Detection limit Buffer 8-Hydroxyquinoline

"Membrane Introduction Mass-spectrometry"
Anal. Chim. Acta 1997 Volume 350, Issue 3 Pages 257-271
N. Srinivasan, R. C. Johnson, N. Kasthurikrishnan, P. Wong and R. G. Cooks*

Abstract: An overview of membrane introduction mass spectrometry (MIMS) is presented and comparisons are made with other direct sample introduction techniques. Special attention is given to the unique advantages and the limitations of newer variants on the MIMS technique, including affinity MIMS, reverse-phase and trap MIMS. The salient features of the interfaces used in MIMS are summarized and the various membrane materials commonly used are delineated. The applicability of MIMS is illustrated via discussion of (i) bioreactor monitoring (represented by yeast fermentation), (ii) environmental monitoring (illustrated by analysis of contaminated ground water samples) and (iii) online chemical reaction monitoring (exemplified by the photolysis of aryl esters). The applicability of MIMS to the analysis of environmental samples, including complex mixtures in water, air and soil, is noted. 77 References
Mass spectrometry Membrane Process monitoring Photochemistry Review

"Flow Injection Online Coprecipitation-preconcentration System Using Copper(II) Diethyldithiocarbamate As Carrier For Flame Atomic Absorption Spectrometric Determination Of Cadmium, Lead And Nickel In Environmental-samples"
Anal. Chim. Acta 1997 Volume 353, Issue 2-3 Pages 181-188
Hengwu Chen*, Jincao Jin and Yufeng Wang

Abstract: A novel flow injection (FI) online coprecipitation-pre-concentration system with diethyldithiocarbamate (DDTC) Copper(LI) being used as a carrier for the flame atomic absorption spectrometric determination of trace cadmium, lead and nickel was developed. Sample solutions, spiked with 120 µg mL-1 Cu2+ and acidified to 0.5 M with hydrochloric acid, were merged online with a 2.1% DDTC solution in a 'T' connector upstream of a knotted reactor. The analytes were coprecipitated with DDTC-Cu2+ and collected on the inner wall of the knotted reactor. The collected species were eluted with isobutyl methyl ketone, and the effluent was transported directly into the nebulizer. Enhancement factors of 26, 45 and 22 were obtained for cadmium, lead and nickel, respectively with a loading period of 30 s. The detection limits (3s) for cadmium, lead and nickel were 0.23, 3.2 and 1.4 µg L-1 respectively, and the relative standard deviations (n=10) were 1.4% for 20 g L-1 cadmium, 2.0% for 200 µg L-1 lead and 2.2% for 80 µg L-1 nickel. At least 50 mg L-1 of such metal ions as Fe3+, Al3+, Mn2+, Zn2+ and Co2+, and 30 mg L-1 of Cu2+ could be tolerated. The method has been successfully applied to the determination of trace cadmium, lead and nickel in various water samples and a standard reference soil. 18 References
Cadmium Lead Nickel Spectrophotometry Preconcentration Coprecipitation Interferences Reference material Knotted reactor MIBK Diethyldithiocarbamate

"Spectrofluorimetric Method For The Determination Of The Total Mercury Content In Sediment And Soil"
Anal. Chim. Acta 1997 Volume 355, Issue 2-3 Pages 151-156
I. Vedrina-Dragojevic*, D. Dragojevi and S. Cadez

Abstract: A spectrofluorimetric method based on fluorescence quenching of rhodamine B with Hg(II) in the presence of potassium iodide for the determination of the total mercury in sediment and soil is described. All forms of mercury are pre-oxidized to ionic mercury by acidic potassium permanganate and finally complete oxidation is achieved by potassium persulphate and heating. Hg(II) was reduced by tin(II) chloride and vapor driven by an air stream into an absorption solution containing potassium permanganate and sulphuric acid, using a closed, recirculating air stream. Fluorescence quenching of rhodamine B is measured in the absorption solution at an excitation wavelength of 485 nm and an emission wavelength of 586 nm. The proposed method gives good recovery of added mercury (mean 98.0%), good repeatability (RSD 1.64%) and reproducibility (RSD 2.17%) and low detection limit (0.7 ng Hg mL-1 of measuring solution). No significant concentration of total mercury present in sediment and soil samples from the largest deposits of oil in Croatia have been found.
Mercury Methylmercury ion Fluorescence Sample preparation Extraction

"Direct Determination Of Phosphate In Soil Extracts By Potentiometric Flow Injection Using A Cobalt Wire Electrode"
Anal. Chim. Acta 1998 Volume 363, Issue 2-3 Pages 191-197
ZuLiang Chen*, Pauline Grierson and Mark A. Adams

Abstract: A system is described for the direct potentiometric flow injection analysis of phosphates using a Co wire electrode. Probably the electrode response to phosphate is a result of Co3(PO)2 ppt. formation at the electrode surface. The electrode response to phosphate depends on the phthalate concentration, carrier pH, flow rate and injected volume. A linear response with a slope of -41±0.5 mV/decade was obtained in the concentration. range of 1.0 x 10^-5 - 5.0 x 10^-3 M with a detection limit of 1 x 10^-6 M, using a carrier solution containing 25 mM potassium hydrogen phthalate at pH 4.0. The proposed method was used for the determination of phosphate in soil extracts with a fast analysis, low cost, high sensitivity and selectivity.
Phosphate Potentiometric stripping analysis Electrode Sample preparation Precipitation

"Flow Injection Biamperometric Determination Of Nitrate (by Photoreduction) And Nitrite With The NO2-/I- Reaction"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 241-249
I. Gil Torr&oacute;a, J. V. Garc&iacute;a Mateob and J. Mart&iacute;nez Calatayuda,*

Abstract: An unsegmented continuous-flow method for the determination of nitrite and nitrate is proposed. Nitrate is photoreduced by UV irradn. with a low-pressure 8 w Hg lamp. The nitrite in the sample and that resulting from the photoredn. of nitrate were used to oxidize iodide ion. Tri-iodide thus formed is detected biamperometrically in excess iodide by using a flow-cell furnished with two Pt electrodes polarized at 100 mV. The limits of detection, throughput and reproducibility (n = 26) thus achieved for nitrite and nitrate are 25 and 50 µg L-1, 27 and 25 h-1, and 1.2 and 1.6%, respectively. The proposed method was used to determine nitrate and nitrite in natural waters, waste waters, soils, meat products and fertilizers. (29 References)
Nitrate Nitrite Biamperometry Electrode Catalysis Reduction column Indirect Photochemistry UV reactor

"Simultaneous Determination Of Cobalt(II) And Nickel(II) In Water And Soil Samples With Sequential Injection Analysis"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 177-186
R. E. Taljaard and J. F. van Staden*

Abstract: The discontinuous nature of the sequential injection technique make it ideally suitable for kinetic determinations One of the advantages of kinetic analysis over equilibrium methods is the possibility of carrying out simultaneous determinations based on the different rates of their reactions with a common reagent. The different rates of the pseudo-first order dissociation of the citrate complexes of cobalt(II) and nickel(II) at pH 8.00 are used as a basis for the kinetic determination of these ions at trace levels in water and soil extracts The reactions are followed by measuring the absorbance of complexes of the metal ions with 4-(2-pyridylazo)resorcinol (PAR) which are formed in a subsequent rapid reaction. EDTA is added to mask the major interferences. The proposed system is fully computerized and is able to monitor Co(II) and Ni(II) in samples at a frequency of 11 samples per h with a relative standard deviation better than 1.2%. The detection limits are 0.14 and 0.20 mg/l for Ni(II) and Co(II), respectively.
Cobalt(II) Nickel(II) Sample preparation Spectrophotometry Sequential injection Simultaneous analysis pH EDTA Complexation Computer Kinetic

"Spectrophotometric Determination Of Micro Amounts Of Nitrite In Water And Soil"
Talanta 1983 Volume 30, Issue 5 Pages 374-376
Qian-Feng Wu and Peng-Fei Liu

Abstract: A spectrophotometric method for determination of µamounts of nitrite in water and soil with p-aminoacetophenone and resorcinol is described. The interference of foreign ions can be eliminated by masking with complexing agents. Beer's law is obeyed up to 20 g of NO2? in 60 mL of solution and the molar absorptivity at 435 nm is 5.27 x 104 l.mole? The color is stable for 10 hr. Results obtained by using the proposed method for water and soil samples agree well with those obtained by the Saltzman standard method.
Nitrite Spectrophotometry

"Potassium Sodium Chloride Integrated Micro-conduits In A Potentiometric Analytical System"
Talanta 1991 Volume 38, Issue 9 Pages 989-993
Cui Hongbo and Sun Junyan

Abstract: An integrated micro-conduit flow injection analysis manifold has been developed that incorporates flow-through K+-, Na+- and Cl--selective electrodes. The characteristics of the electrodes were evaluated, showing a rapid response of 10 s, a reproducibility of ±0.1 mV, and stability over 8 h. Samples of water, soil extracts and serum were analyzed, giving results in agreement with those obtained by flame-photometric and AgNO3 titrimetric methods.
Chlorine Potassium Sodium Electrode Potentiometry Sample preparation

"Determination Of Thallium In Soils By Flow Injection Differential Pulse Anodic-stripping Voltammetry"
Talanta 1992 Volume 39, Issue 3 Pages 221-227
Zenon Lukaszewski and Wlodzimierz Zembrzuski

Abstract: The soil was decomposed in a bomb with HF - HCl - HNO3 at 135°C, and after evaporation in the presence of H2O2 the residue was dissolved in hot HCl. Ascorbic acid and EDTA were added to give concentration. of 0.1 M and 0.15M, respectively, and the pH was adjusted to 4.5. The solution was analyzed by pre-concentration. at -0.850 V vs. SCE for 1 to 3 min depending on the Tl concentration. Recoveries of Tl added at 250 ppb averaged 94% with a coefficient of variation (n = 6) of 7.2%. A detection limit of 10 ppb with 0.5 g of soil could be achieved with a 10 to 15-min pre-concentration. A relatively simple and quick method for the determination of thallium is soils is described. The method does not require any separation prior to determination Total decomposition of the sample was performed in a Teflon bomb. The interferences of iron, aluminum, and manganese were removed by media exchange performed in a flow injection measuring system, and the other interferences were removed by the use of the base electrolyte consisting of 0.15 M EDTA and 0.1 M ascorbic acid. The contents of thallium in the examined samples of soil were between 100 and 350 ppb.
Thallium Sample preparation Voltammetry Interferences EDTA

"Time-based Injector Applied To The Flow Injection Spectrophtometric Determination Of Boron In Plant Materials And Soils"
Talanta 1993 Volume 40, Issue 12 Pages 1967-1974
Pablo Carrero, J. L. Burguera, M. Burguera and C. Rivas

Abstract: Coffee plant material was dried for 3 days at 70°C, ground and ashed for 2 h at 500°C. The residue was mixed with 0.1 M HCl, filtered and the filtrate diluted with 0.1 M HCl. Soil was air dried for 5 days, ground, refluxed for 10 min with water, cooled, mixed with calcium chloride dihydride and filtered. The filtrate was mixed with saturated CaOH, evaporated to dryness, ignited and dissolved in 0.1 M HCl. The sample solution, 1% azomethine-H and 2 M phosphate buffer of pH 6.9 containing 5% EDTA were mixed in a ratio of 3:1:1 in a reaction coil and passed to a holding coil using a suction device. The time-based injector delivered electronic pulses to a solenoid valve which closed the tube from the suction device and diverted the water carrier stream (5.5 ml/min) to receive 0.15 mL portions from the holding coil. The reaction mixture then passed to the detector for measurement at 420 nm. Calibration graphs were linear for 0.1-80 mg/l of B, but in practice were restricted to 0.1-6 mg/l. The detection limit was 50 µg/l with RSD of 1-2.8%. Recoveries of 2, 4 and 6 µg/g of B were 98-101.7% in leaves, 96.5-99.2% in coffee beans and 96-98.5% in soil.
Boron Spectrophotometry

"Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate By Flow Injection Analysis"
Talanta 1996 Volume 43, Issue 7 Pages 1009-1018
M. J. Ahmeda, C. D. Stalikasa, S. M. Tzouwara-Karayannia and M. I. Karayannisa,*

Abstract: Meat products, flour, soil, beer and cheese were prepared and digested by the AOAC method ['Official Methods of Analysis of the Association of Official Analytical Chemists', Helrich (Ed.), Association of Official Analytical Chemists, Arlington, VA, USA, 1990]. The digests were filtered and the filtrate or filtered water was diluted with 0.4 M NH4Cl. The prepared samples or standards were injected into a carrier stream (0.4 ml/min) of 0.4 M NH4Cl, the stream was split into two and one stream passed through a glass reaction column (2 cm x 3 mm i.d.) packed with copper particles and a reduction column (10 cm x 3 mm i.d.) packed with copperized cadmium granules. The reduced stream merged with a reagent stream (1 ml/min) of 7.24 mM 3-nitroaniline/3.86 mM N-(1-naphthyl)- ethylenediamine dihydrochloride (1:5), the resulting stream passed through a reaction coil (50 cm) and the absorbance was measured at 535 nm. The second part of the stream by-passed the reduction columns, merged with the reagent stream and the absorbance was measured. Calibration graphs were linear for 0.01-2.2 µg/ml of nitrite and 0.1-3.5 µg/ml of nitrate with detection limits of 1 ng/ml and 10 ng/ml, respectively. The RSD (n = 5) were 0.1-2% over the calibration range for nitrate and nitrite. The permissible levels of interfering ions are tabulated.
Nitrate Nitrite Sample preparation Spectrophotometry Interferences Column Reduction column

"Flow Injection Analysis Of Environmental Samples For Nitrate Using An Ion Selective Electrode"
Analyst 1977 Volume 102, Issue 1219 Pages 705-713
E. H. Hansen, Animesh K. Ghose and J. Ruzicka

Abstract: NO3- in soil extracts, wastewater, and fertilizer solutions was determined by addition of a pH 9.5 buffer of 10^-2 M Na tetraborate + 10^-2 M NaOH and measuring the peak max. value in a flow injection system with a NO3--selective electrode. Aqueous extracts of particulate NO3- in air were analyzed without pretreatment. The electrode consisted of tetraoctylammonium bromide in di-Bu phthalate and was calibrated at 10^-5 - 10^-2 M NO3-. For injection of 0.3 mL samples the anal. rate was 90 samples/h. The standard deviation was typically 0.2-0.5 mV, equivalent to 1-2%. The electrode lifetime was 2-3 months. A method is proposed for identifying and correcting for the presence of interferents by observing the shape of each peak and determining its negative elevation. Based on the flow injection principle and employing a nitrate electrode situated in a flow-through cell, a simple, reliable and sensitive method for the automated determination of nitrate and its use for analyzing soil extracts, waste waters, fertiliser solutions and air samples are described. At a sampling rate of 90 samples per hour a standard deviation of only 1-2% is typical. A new approach to identifying and correcting for the presence of interfering species in potentiometric measurements is discussed.
Nitrate Electrode Apparatus Interferences

"Determination Of Ammonia In Low Concentrations With Nesslers Reagent By Flow Injection Analysis"
Analyst 1979 Volume 104, Issue 1234 Pages 47-54
F. J. Krug, J. Ruzicka and E. H. Hansen

Abstract: NH3 (0.5-6.0 ppm) was determined turbidimetrically at 410 nm with good precision and accuracy in 30 µL samples of natural water and soil extracts at a rate of 100 samples/h by using Nessler's reagent and continuous-flow injection. Variables such as optimum reagent concentrations, alkalinity, flow rates, mixing coil lengths, temperature, and the presence of protective colloids in the flow injection system were studied.
Ammonia Sample preparation Turbidimetry Optimization

"Determination Of Nitrogenous Gases Evolved From Soils On Closed Systems"
Analyst 1979 Volume 104, Issue 1239 Pages 538-544
C. J. Smith and P. M. Chalk

Abstract: A simple method is described for determining nitrogen oxide and nitrogen dioxide, evolved from soils, in closed systems. These gases are absorbed by an acidic solution of potassium permanganate, and the resulting nitrate is determined by a steam distillation method. Excess of permanganate is reduced with iron(II) sulphate and neutralized with sodium hydroxide solution. Ammonium in solution is removed by distillation with magnesium oxide, and nitrate is determined by distillation after reduction to ammonium by Devarda's alloy.Nitrogen and dinitrogen oxide evolved from soils are measured using gas chromatography on a single 0.61 m column of molecular sieve 5A, temperature programmed to 250°C at 39°C min-1, after an initial period of 1 min at 35°C. A complete analysis requires 19.5 min, and 2 µg of nitrogen can be determined quantitatively for each gas.
Nitrate Nitrogen Nitrogen monoxide Nitrogen dioxide GC Conductometry Conductometry Closed loop

"Rapid Determination Of Chromium(VI) By Flow Injection Analysis"
Analyst 1980 Volume 105, Issue 1248 Pages 292-295
S. Storgaard J&oslash;rgensen and Marisa A. B. Regitano

Abstract: The photometric determination of chromium(VI) in natural waters and soil extracts as the 1,5-diphenylcarbazide complex is well established as a standard method.(1) The complex is formed rapidly, has a high absorptivity at 540 nm and the method is highly selective when the pH is kept at 1-2. For rapid analysis of small sample volumes this method appears to be ideally suited for adaptation to the continuous flow injection technique of Ruzicka and co-workers.(2-4) The present investigation was undertaken when chromium(VI) had to be determined in a considerable number of soil extracts during a study of the behavior of chromium in soils.(5)
Chromium(VI) Spectrophotometry Extraction

"Flow Injection Analysis System For Determining Soil PH"
Analyst 1983 Volume 108, Issue 1289 Pages 1013-1017
Tony E. Edmonds and Grace Coutts

Abstract: The system, which is described in detail, is constructed from readily available components and can analyze 90 samples h-1. Air-dried soil samples (15 g) sifted to <2 mm were extracted with 25 mL of 0.01 M CaCl2, and the extracts were filtered and injected into a Rheodyne type 50 four-way PTFE rotary injection valve with a 0.5 mL sample loop. A Watson-Marlow 501 peristaltic pump with a 501M pump head adapted into a five-channel six-roller occlusion device was used to pump the sample and buffer solution (1 µM-NaH2PO4 - 1 µM-Na2HPO4 - 0.01 M CaCl2; pH 5.54) to the injection valve. The mixture was then passed to a Russell UTTFC/CAP pH electrode followed by a silver - AgCl reference electrode. The pH standards used were 50 µM-K H phthalate - 0.01 M CaCl2 (pH 4.76) and 50 µM-Na2B4O7 - 0.01 M CaCl2 (pH 8.71). For soil samples of pH 6.8 and 5.1, the coefficient of variation (n = 20) were 0.8 and 0.4%, respectively. The results are precise, but are not necessarily accurate owing to the nature of soil slurries.
pH Electrode Potentiometry

"Determination Of Silicon In Soil Extracts By Flow Injection Analysis"
Analyst 1985 Volume 110, Issue 2 Pages 177-180
Ole K. Borggaard and S&oslash;ren Storgaard J&oslash;rgensen

Abstract: Flow injection analysis was used for spectrophotometric determination (at 35 h-1) of dissolved Si in complex aqueous media, e.g., soil extracts. Molybdenum blue is formed by the reduction of β-molybdosilicate by ascorbic acid and measured at 816 nm. Determination must be performed at ~80°C to accelerate the formation of β-molybdosilicate and the decomposition of molybdophosphate, formed in phosphate-containing solution. The detection limit is 30 ng mL-1 of SiO2 with a coefficient of variation of 2%. EDTA, Al, Fe, and P do not interfere at naturally occurring levels in soil extracts diluted to contain <1.0 µg mL-1 of SiO2; dithionite requires oxidation by aeration before Si determination. Results for Si in seven soil samples by flow injection analysis were in close agreement with those by a manual photometric procedure.
Silicon Sample preparation Spectrophotometry Heated reaction Interferences

"Flow Injection Determination Of Inorganic Bromide In Soils With A Coated Tubular Solid-state Electrode"
Analyst 1987 Volume 112, Issue 5 Pages 595-599
Jacobus F. van Staden

Abstract: The flow injection system and construction of the cited electrode are described. Soil samples were shaken for 30 min with I adjustment buffer containing 1 M KNO3 and 100 mg L-1 of Cl-. The suspension was centrifuged, the supernatant solution was filtered, 30 µL aliquots of the filtrate were injected into the carrier stream of 1 M KNO3 pumped at 3.9 mL min-1, and the solution was passed through a 105-cm mixing coil. Additional KNO3 was added at 1.4 mL min-1 downstream, and mixed in a second coil (160 cm) before the potential was measured at the coated tubular indicator electrode (vs. a double-junction reference electrode). The presence of Cl- in the KNO3 eliminated Cl- interference in the determination of Br-. The method was suitable for the determination of 1 to 5000 mg L-1 of Br-. The sampling rate was 80 h-1. The coefficient of variation was 1.6%.
Bromide Electrode Potentiometry Interferences

"Online Dilution, Steady-state Concentrations By Tandem Injection And Merging Stream. Application To Inductively Coupled Plasma Atomic Emission Spectrometry Sequential Multielement Soil Analysis"
Analyst 1990 Volume 115, Issue 11 Pages 1411-1417
Yecheskel Israel and Ramon M. Barnes

Abstract: Recently developed flow injection on-line dilution methods, i.e., the merging stream and tandem injection, which yield steady-state concentrations, have been applied to the analysis of reference soil sample digests by inductively coupled plasma atomic emission spectrometry. Direct or on-line dilution determinations were applied, with dilutions ranging from 1.8 to 15 for both dilution methods. Higher dilutions are not feasible, especially when trace elements are involved. A variable speed peristaltic pump was used to limit the total flow-rate by the merging-stream dilution method to 2 mL min-1. This permitted the design of a flow module with one set of coils and a flow configuration suitable for all dilutions. Varying the dilution required only the variation of the peristaltic pump flow tube diameters. Selecting the required dilution for the tandem injection method was carried out with no manual operations and involved only pre-programming of the injection time and the injection cycle period. The results obtained exhibit comparable accuracy and precision for major and minor elements to those obtained by direct determination. By varying the dilution for the determination of trace elements, screening the optimum dilution(s) suitable for the determination of each trace element is possible.
Spectrophotometry Dilution

"Determination Of Orthophosphate In Waters And Soils Using A Flow Analyser"
Analyst 1990 Volume 115, Issue 1 Pages 65-67
David J. Malcolme-Lawes and Koon Hung Wong

Abstract: Samples (0.3 ml) were injected into a high performance continuous-flow analyzer. (carrier 1.5% of NaCl in 0.12 M HNO3) downstream of the manifold where the reagents NH4MoO4, K - Sb tartrate (catalyst) and L-ascorbic acid were pre-mixed. Absorbance of the heteropolymolybdenum blue complex was measured at 670 nm. Interferences from ions commonly found in potable waters were small. The calibration graph was rectilinear for 100 ppm, and the detection limit was 4.8 ppb of P. Sample throughput was >120 h-1 at 4 ppm. The method was applied to soil samples after extraction with NaHCO3 solution
Phosphate Spectrophotometry Sample preparation Catalysis Interferences Calibration Detection limit PPB

"Determination Of Total And Free Cyanide In Water After Distillation"
Analyst 1992 Volume 117, Issue 6 Pages 1009-1012
Johannes C. L. Meeussen, Meindert G. Keizer and Wendy D. Lukassen

Abstract: Separation of total CN- from SCN- was achieved by illumination with (i) standard UV radiation and replacement of the quartz coil with a Pyrex coil, (ii) an 8-W fluorescent lamp in the continuous-flow system and (iii) a fluorescent lamp 1 to 170 h before analysis, with no illumination during analysis. Samples were kept at pH 12. Separation of free CN- from hexacyanoferrate and SCN- was performed by distillation of samples at pH 4 in a citrate buffer solution in the presence of Cu2+. Decomposition of hexacyanoferrate and evaporation of SCN- as HSCN was prevented. The method was applied to the determination of total CN- and free CN- in soil extracts by extraction of two contaminated soils with 0.25 M NaOH for 3 h on a boiling-H2O bath (details given). Both methods combine the advantages of sample distillation with a high specificity for total and free CN-.
Cyanide, total Cyanide, free Sample preparation UV reactor Photochemistry

"Potentiometric Detection In Flow Injection Without Use Of A Conventional Reference Electrode"
Analyst 1992 Volume 117, Issue 8 Pages 1335-1337
Ren-Min Liu, Dao-Jie Liu and Ai-Ling Sun

Abstract: A flow injection system is described which has two ion-selective electrodes arranged in parallel to serve as the detector. Two types of ion can be determined by using a double sample loop and an asynchronous sample injection technique. The carrier stream channels of the electrodes alternate between the sampling and sample injection modes. The potential of the electrode of the channel in the sampling state is kept constant and this then serves as the reference electrode. The method was used for the determination of F- and NO3--N in natural waters, Na and K in natural waters, and K and NO3--N in soil extracts. The calibration graphs were rectilinear in the ranges 0.02 to 2000, 0.8 to 6000, 0.5 to 2000 and 0.3 to 3500 ppm for F-, NO3--N, Na and K, respectively. The sampling rates were 180 h-1 for F- and NO3--N and 120 h-1 for Na and K. An ion-selective electrode flow injection system has been developed with two ion-selective electrodes arranged in parallel in a flow injection system. The system does not contain a conventional reference electrode, and no liquid junction is present. The sample is injected into the two carrier streams alternately and gives a potential response at the electrode. The proposed method is simple and convenient and was applied successfully to the determination of fluoride and nitrate in natural waters, the determination of sodium and potassium in natural waters and the determination of potassium and nitrate in soil extracts.
Nitrate Potassium Sodium Fluoride Potentiometry Electrode Electrode Electrode Electrode Sample preparation

"Continuous-flow Method For The Determination Of Phenols At Low Levels In Water And Soil Leachates Using Solid-phase Extraction For Simultaneous Preconcentration And Separation"
Analyst 1996 Volume 121, Issue 1 Pages 1-6
Zheng-liang Zhi, Angel R&iacute;os and Miguel Valc&aacute;rcel

Abstract: Soil was extracted with water and filtered. Water (tap, river) was filtered. The filtrates were adjusted to pH 2 with 12 M HCl and the ionic strength was brought to 0.34 M with NaCl. The sample was pumped continuously (4.8 ml/min) for 5 min through a column (4 cm x 2.5 mm i.d.) of Amberlite XAD-4, previously conditioned with 0.01 M HCl. The column was then washed with water at pH 2 for 30 s. Elution of the analytes was effected by continuously passing a stream (1 ml/min) of 0.1 M NaOH through the column. The eluate was merged with a stream (0.4 ml/min) of 1% 4-aminoantipyrine in borate buffer of pH 9-10, then with a stream (1 ml/min) of 4% K2S2O8 of pH 11 and finally with a stream (1 ml/min) of CHCl3 propelled from a displacement bottle. The mixture was passed through a 2 m extraction coil and the aqueous and organic phases were separated by means of a membrane phase separator. The absorbance of the organic phase was measured at 460 nm. The calibration graph was linear for 0.5-60 ng/ml phenol, the detection limit was 0.2 ng/ml and the RSD (n value not given) was 2.7%. The throughput was 8 samples/h. Recoveries of phenol were 91.6-108.3%.
Phenols Spectrophotometry Sample preparation Preconcentration Amberlite Phase separator Solid phase extraction

"Simple Flow Injection Spectrofluorimetric Method For Speciation Of Thallium"
Analyst 1996 Volume 121, Issue 6 Pages 813-816
Tom&aacute;s P&eacute;rez-Ruiz, Carmen Mart&iacute;nez-Lozano, Virginia Tom&aacute;s and Rocio Casaj&uacute;s

Abstract: A flow injection method for determining Tl(I) and/or Tl(III) is described. For Tl(I) determination, the sample (200 µL) was injected into a carrier stream (0.5 ml/min) of 1 M HCl and merged with an aqueous stream (0.5 ml/min). The mixture was passed through a 30 cm reaction coil after which the fluorescence intensity was measured at 419 nm (excitation at 227 nm). For Tl(I) plus Tl(III) (i.e., total Tl) determination, the above procedure was repeated, except that the aqueous stream was replaced by a stream (0.5 ml/min) of 0.1 mM thiourea. Tl(III) in the sample was determined by difference. The calibration graphs were linear for 0.05-10 and for 0.1-10 µM Tl(I) and Tl(III), respectively. The RSD (n = 10) were 1%. The throughput was 90 samples/h. Recoveries of Tl(I) and Tl(II) from synthetic mixtures were 93%. The method was applied to soil and zinc ores.
Thallium(I) Thallium(III) Fluorescence Speciation

"Determination Of Lead In Soil Samples By In-valve Solid-phase Extraction - Flow Injection Flame Atomic Absorption Spectrometry"
Analyst 1996 Volume 121, Issue 10 Pages 1413-1417
Ponlayuth Sooksamiti, Horst Geckeis and Kate Grudpan

Abstract: Soil (0.3 g) was digested with 5 mL concentrated HNO3 and 1 mL 30% H2O2 in a microwave digester at 250-650 W for 20 min. The digest was filtered and diluted to 100 mL with 1 M HNO3. A portion of the resulting solution was loaded (4 ml/min) onto a column (2.5 cm x 3 mm i.d.) of Sr. Spec SPS resin (Eichrom), which was incorporated in a flow injection system. Elution of Pb from the column was effected with 0.05 M ammonium oxalate (4 ml/min). The eluate was analyzed for Pb by flame AAS at 217 nm. The calibration graph was linear up to 5 µg Pb, the detection liwas 0.08 µg and the RSD (n = 15) was 4.1%. The recovery of Pb was 95-98%. The results obtained agreed with those obtained by ETAAS.
Lead Sample preparation Spectrophotometry Sample preparation Method comparison Resin Solid phase extraction Preconcentration

"Simultaneous Spectrofluorimetric Determination Of Selenium(IV) And (VI) By Flow Injection Analysis"
Analyst 1997 Volume 122, Issue 3 Pages 221-226
M. J. Ahmed, C. D. Stalikas, P. G. Veltsistas, S. M. Tzouwara-Karayanni and M. I. Karayannis

Abstract: A sample (100 µL) was injected into a carrier stream of 2 M H2SO4 at a flow rate of 0.1 ml/min and mixed with a reagent stream of 0.2 mM 2-(α-pyridyl)thioquinaldinamide in propan-2-ol at a flow rate of 0.3 ml/min. The fluorescence intensity due to Se(IV) was measured at 500 nm (excitation at 350 nm). A second portion (100 µL) was then injected into the carrier stream and passed through a coil (40 cm x 0.8 mm i.d.) where it was irradiated at 254 nm. The irradiated sample stream was then mixed with the reagent stream and the fluorescence intensity due to total Se was measured. Se(VI) was determined from the difference in the two fluorescence intensity values. The calibration graphs were linear from 0.01-2.2 and 0.1-2.4 µg/ml Se(IV) and Se(VI), respectively; corresponding detection limits were 1 and 10 ng/ml. RSD were 0.1-2% (n=5). The throughput was 25 samples/h. The method was applied to the analysis of alloys, hair, tap and lake water, sediments, soil, tea, flour and eggs. A simple, sensitive, highly selective, automatic spectrofluorimetric method for the simultaneous determination of selenium (IV) and (VI) as selenite-selenate by flow injection analysis (FIA) has been developed. The method is based on the selective oxidation of the non-fluorescent reagent 2-(α-pyridyl)thioquinaldinamide (PTQA) in acidic solution (1.5-3.0 M H2SO4) by Se(IV) to give an intensely fluorescent oxidation product (lambda ex =350 nm; lambda em = 500 nm). Selenium (VI) is reduced online to Se(IV), in a reduction coil installed in a photo- reactor, which is then treated with PTQA and the fluorescene due to the sum of Se(IV) and Se(VI) is measured; Se(Vi) is determined from the difference in fluorescence values. Various analytical parameters, such as effect of acidity, flow rate, sample size, dispersion coefficient, temperature, reagent concentration and interfering species were studied. The photo-reduction conditions were optimized, with an FIA procedure, for Se(VI) on the basis of its reduction efficiency. The calibration graphs were rectilinear for 0.1-2.4 µg mL-1 of Se(VI) and 10 ng mL-1 - 2.2 µg mL-1 of Se(IV), respectively. The method was applied to the determination of Se in several Standard Reference Materials (alloy, sediments and tea), as well as in some environmental waters (tap and surface water), food samples (flour and egg), a biological sample (human hair), soil sample and in synthetic mixtures. Up to 25 samples per hour can be analyzed with an RSD approximately 0.1-2%.
Selenium(IV) Selenium(VI) Fluorescence Speciation Photochemistry Selectivity Reference material Interferences

"Determination Of Cadmium In Environmental Samples By Hydride Generation With In Situ Concentration And Atomic Absorption Detection"
Analyst 1997 Volume 122, Issue 4 Pages 331-336
Henryk Matusiewicz, Mariusz Kopras and Ralph E. Sturgeon

Abstract: A continuous-flow AAS system for Cd determination is described. A Cd solution acidified with HCl was mixed with 1 µg/ml Co and 0.5% thiourea (and also with 0.01 M didodecyldimethyl-ammonium bromide for reaction with KBH4) and diluted to 1 mL with water. The resulting solution was aspirated at a flow rate of 1 ml/min into a continuous-flow system and merged with a stream of either 2% NaBH4 or 4% KBH4 at a flow rate of 1 ml/min. The mixture was passed through a reaction cell/gas-liquid separator maintained at 50°C and the volatile Cd species evolved were carried by an Ar stream on to the inner wall of a GF for in situ pre-concentration at 200°C. Cd analysis was by ET AAS with atomization at 1800°C for 3 s; detection was at at 228.8 nm. The detection limit was 10 ng/l Cd with KBH4 as reagent. RSD were 10^-14% (n = 10). The method was applied to several environmental and biological CRM. The results obtained agreed with the certified values.
Cadmium Spectrophotometry Heated reaction Volatile generation Reference material Phase separator Preconcentration Volatile generation

"Integrated Automatic Determination Of Nitrate, Ammonium And Organic Carbon In Soil Samples"
Analyst 1997 Volume 122, Issue 4 Pages 309-313
Evaristo Ballesteros, Angel R&iacute;os and Miguel Valc&aacute;rcel

Abstract: For nitrate and ammonium determination, soil was extracted with 2 M KCl. For organic C determination, soil was treated with K2Cr2O7/H2SO4 followed by dilution with water. All sample solutions were aspirated into a flow system through a filtration probe containing a hydrophobic PTFE membrane. For nitrate determination, the sample solution was passed through a Cu-coated Cd column before reaction with N-(1- naphthyl)-ethylenediamine and sulfanilamide; absorbance was measured at 540 nm. For ammonium determination, the sample solution was mixed with EDTA before reaction with phenol/nitroprusside in the presence of hypochlorite buffer of pH 11.4-12.3 at 50°C; absorbance was measured at 636 nm. Organic C was determined by mixing the sample solution with 15% H2SO4 and measuring the absorbance at 600 nm. The calibration graphs were linear from 0.25-4 and 0.4-8 µg/ml nitrate and ammonium, respectively, and from 0.1-2% for organic carbon. The detection limits were 0.1 µg/ml for both nitrate and ammonium, and 0.05% for organic C. RSD were 2-2.6% (n = 11). Recoveries were 87-102%. The throughput was 15-60 samples/h. An automated photometric method for the sequential determination of nitrate, ammonium and organic carbon in soils by use of a single-line flow injection assembly is reported, but differently programmed for the assay of the individual analytes, These analytes, which are determined by using suitable photometric reagents, are directly related to the nutritional properties of soil, A filtration probe was used for the continuous filtration of soil extract, The precision, expressed as RSD, was 2.0, 2.6 and 2.1% for nitrate, ammonium and organic carbon, respectively. The proposed method features a high throughput and low reagent consumption, and requires minimal sample handling, Its performance was tested in routine analyzes of soil samples, all with satisfactory results. (26 References)
Ammonium, nitrogen Carbon, organic Nitrate Spectrophotometry Sample preparation Automation Multicomponent Selectivity Teflon membrane EDTA Heated reaction Reduction column Reagent consumption

"Multi-insertion Of Small Controlled Volumes Of Solutions In A Flow Assembly For Determination Of Nitrate And Nitrite With Proflavin Sulfate"
Analyst 1998 Volume 123, Issue 3 Pages 429-434
J. Mart&iacute;nez Calatayud, J. V. Garc&iacute;a Mateo and V. David

Abstract: A simple, maintenance-free, noncontaminating and completely automated flow system was developed for non-simultaneous determinations of nitrite and nitrate, in which spectrophotometric measurements at 328 nm were performed on the nitrite reaction with proflavin sulfate [bis(3,6-diaminoacridinium)sulfate]. The sample solutions were automatically inserted into phosphate buffer (pH 6.8) containing 10 mM EDTA by using a programmable solenoid valve; then they flowed through a 6.4 m x 0.5 mm id PTFE coil, wrapped around an 8 W low pressure Hg lamp, and finally they merged with a HCl solution of proflavin. With the lamp off the nitrite in the sample was selectively measured with a sensitivity of 0.75 x 104 absorbance (linearity range up to 0.6 absorbance; detection limit of 1.9 x 10^-7 M). With the lamp on, to determine the sum of nitrite + nitrate there was a decrease in sensitivity of 41% vs. that of the selective variant for nitrite determination The sample throughput was 15 h-1 and the relative standard deviation at a 6.4 x 10^-5 M level of nitrate was 0.4% (n = 15). Many interferences were studied and simple methods of correcting for them were applied to analyze samples such as waters, soils, fertilizers and meat. (26 References)
Nitrate Nitrite Spectrophotometry Automation Injection technique UV reactor Photochemistry Buffer Interferences EDTA Differential detection

"Application Of Flow Injection Analysis Adsorption-elution Protocols For Aluminum Fractionation"
Analyst 1998 Volume 123, Issue 5 Pages 797-802
Kipton J. Powell

Abstract: FIA (flow injection analysis) is a widely used technique for trace element analysis, but has a number of inherent problems. When used to determine the 'free' metal concentration, the 'normal' reaction time in the manifold, 15-30 s, promotes a significant sequestration of metals from labile and pseudo-labile complexes. Also there is potential for matrix components other than the target analyte to affect the rate of the analyte-reagent reaction. This may lead to an over- or under-estimate of the amount of labile metal relative to calibrations based on simple aqueous standards These problems can be minimized by use of flow systems with much shorter 'reaction times' and by sepg. the analyte fractionation step from the analyte-reagent reaction step. This can be achieved by use of online adsorbents from which the captured analyte is eluted prior to the analyte-reagent reaction. This is illustrated for the fractionation of Al by use of ~1 s contact time with an oxine-derivatized gel. Real-time anal. of non-retained fractions coupled with selective elution of retained species provides the concentrations. of three fractions:'free Al' [Al3++Al(OH)2++AL(OH)2+], labile organic Al' and 'Al13' hydroxy polymers. Quant. separation of Al and Fe is achieved. For 'free Al' the linear working range is 0.3-16 µm, the LOD 70 nm and the RSD at 2 µm Al is 3.7%. The method is compared to conventional FIA for determination of 'reactive Al' in soil solutions and is applied to the Al-complexation capacity and pH-dependent Al binding of a fulvic acid, and in the correlation of plant growth with Al fractions in soil solutions.
Aluminum, free Aluminum, labile Aluminum, reactive 8-Hydroxyquinoline Complexation Speciation Solid phase reagent

"Evaluation Of The Determination Of Mercury At The Trace And Ultra-trace Levels In The Presence Of High Concentrations Of NaCl By Flow Injection-cold Vapor Atomic Absorption Spectrometry Using SnCl2 And NaBH4 As Reductants"
Analyst 1998 Volume 123, Issue 6 Pages 1219-1222
O. Haase, M. Klare, K. Krengel-Rothensee and J. A. C. Broekaert

Abstract: The influence of different concentrations of NaCl (0-20%(m/v)) on the analytical figures of merit for the determination of Hg by flow injection-CVAAS was studied. The determination was performed with and without pre-concentration by Au amalgamation and by employing different reducing agents, NaBH4 and SnCl2. When using the reductant SnCl2, stable operation both with and without pre-concentration was obtained, resulting in RSDs <5% (n ≥ 30), even in the presence of high concentrations of NaCl. Without pre-concentration the sensitivity was a function of the concentration. of NaCl (between 0.033 and 0.013 mL ng-1). With pre-concentration the sensitivity could be improved by a factor of 2.5 (i.e., from 0.084 to 0.037 mL ng-1, depending on the concentration. of NaCl). With the reducing agent NaBH4, sufficient stability for routine anal. was observed only without pre-concentration (relative standard deviation ≤2%, n = 45) and a sensitivity of 0.022 mL ng-1 was obtained for matrix-free solutions In the presence of high concentrations. of NaCl the sensitivity increased up to 0.030 mL-1 ng, but owing to the unsystematically unstable blank values it was not a monotonic function of the concentration of NaCl. The use of pre-concentration in the case of NaBH4 was hampered by the Au trap being covered with gaseous reaction products or entrained droplets as a result of the generation of foam in the gas-liquid separator. This could be improved using two gas-washing bottles (NaOH, H2O). With the different methods, for which the detection limits finally were 15-230 pg mL-1 (without) and 2 and 11 pg mL-1 (with pre-concentration), Hg was determined in five standard reference samples of soil and sedimented sludge at the ng g-1 to µg g-1 level subsequent to their dissolution with aqua regia.
Mercury Spectrophotometry Method comparison Optimization Reference material Amalgamation Interferences Ionic strength Dissolved solids

"Spectrofluorometric Determination Of Paraquat By Manual And Flow Injection Methods"
Analyst 1998 Volume 123, Issue 7 Pages 1577-1581
Tom&aacute;s P&eacute;rez-Ru&iacute;z, Carmen Mart&iacute;nez-Lozano, Virginia Tom&aacute;s and Jos&eacute; Fenoll

Abstract: The reaction involving the formation of a fluorescent charge-transfer complex between paraquat and benzaldehyde was studied in ethanol-water medium. In the presence of a large excess of benzaldehyde, the fluorescence intensity is linearly related to paraquat concentration. from 0.13 to 7.4 µg mL-1. The method can be easily adapted to a flow system using a two-channel manifold, the peak height being proportional to the paraquat concentration. over the range 1.6-22.3 µg mL-1. Manual and flow injection procedures were satisfactorily applied to the determination of paraquat in commercial herbicides, waters, soils and potatoes.
Paraquat Fluorescence Complexation

"Flow Injection Calibration Of Inductively Coupled Plasma Atomic Emission Spectrometry Using The Generalized Standard Additions Method"
J. Anal. At. Spectrom. 1988 Volume 3, Issue 5 Pages 673-678
Maria Fernanda Gin&eacute;, Francisco Jos&eacute; Krug, Henrique Bergamin Filho, Boaventura Freire dos Reis, Elias Ayres Guidetti Zagatto and Roy Edward Bruns

Abstract: The generalized standard-additions method, employing least squares regression, was applied to obtain the calibration matrix for multi-element analysis by ICP-AES. The method is based on response variations following known additions of interfering and test elements. As a number of additions are required, a flow injection system that permits high sampling rates and low consumption of sample is used. The zone sampling approach is applied as it allows selection of regions with different mean concentration. The flow injection apparatus is coupled to an ICP-AES instrument, the operating parameters of which are adjusted to minimize inter-element effects. The method was applied in the analysis of rock reference materials and results agreed well with certified values. The reproducibility of the calibration matrix was >99.5%.
Trace elements Spectrophotometry Interferences Reference material Standard additions calibration Zone sampling

"Direct Atomic-spectrometric Analysis By Slurry Atomization. 8. Flow Injection Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 2 Pages 219-222
Andrea J. Ambrose, Les Ebdon, Michael E. Foulkes and Philip Jones

Abstract: The analysis of slurries by flow injection ICP-AES was studied, with particular reference to the controlling parameters, viz, spray chamber design, sample injection volume, carrier stream flow rate and effect of torch injector size. A novel low-volume spray chamber was developed. Sample injection volume of 500 µL gave equivalent sensitivity to that of continuous nebulization; the optimum torch injector tube i.d. was 3 mm. By using this technique, excellent agreement with certified values and precision of 2% were obtained in determination of Ca, Fe, Mg, Mn, Cu and V in reference soils. (For Part VII see Anal. Abstr., 1989, 51, 1B192).
Calcium Copper Iron Magnesium Manganese Valine Spectrophotometry Slurry Nebulizer Optimization Reference material

"Sample Analysis By Online Isotope-dilution Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 8 Pages 761-766
Alexandra L&aacute;sztity, Mikl&oacute;s Viczi&aacute;n, Xioaru Wang and Ramon M. Barnes

Abstract: A system for online isotope-dilution ICP-MS was developed by coupling commercial flow injection instruments with an ICP-MS instrument. The performance of the system was investigated by determination of Pb in various standard reference materials (including soil, sediment, paint, blood and food), with dilution with 206Pb or radiogenic Pb isotope standards. Both steady-state merging and multiple injections were employed, the former being preferred, the precision was 1%.
Lead Mass spectrometry Mass spectrometry Reference material

"Inductively Coupled Plasma Spectrometry In The Study Of Childhood Soil Ingestion. 2. Methodology"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 8 Pages 727-735
Xioaru Wang, Alexandra L&aacute;sztity, Mikl&oacute;s Viczi&aacute;n, Yescheskel Israel and Ramon M. Barnes

Abstract: In a study aimed at quantifying the amount of soil ingested by infants and toddlers, faeces and urine collected in commodes or on diapers, together with home and pre-school dust, soil and food samples, were analyzed for Al, Ba, Mn, Si, Ti, V, Y and Zr by ICP-AES with multi-channel and sequential instruments, and V, Y and Zr were also determined by ICP-MS with flow injection sample introduction. Protocols are described for sample prep., and for online dilution and calibration for ICP-MS. Results obtained on standard solution and on reference soil and dust were in good agreement with certified or recommended values, and results by ICP-AES and ICP-MS were not statistically different, although those by ICP-MS were more precise. Flow injection ICP-MS is recommended for determining V, Y and Zr, which are present at low concentration.
Aluminum Barium Manganese Silicon Titanium Yttrium Sample preparation Spectrophotometry Mass spectrometry Reference material

"Determination Of Technetium-99, Thorium-230 And Uranium-234 In Soils By Inductively Coupled Plasma Mass Spectrometry Using Flow Injection Preconcentration"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 9 Pages 927-933
Mark Hollenbach, James Grohs, Stephen Mamich, Marilyn Kroft and Eric R. Denoyer

Abstract: A new method is described for the determination of 99Tc, 230Th, and 234U at ultratrace levels in soils. The method used flow injection (FI) for online pre-concentration of 99Tc, 230Th and 234U before detection using inductively coupled plasma mass spectrometry (ICP-MS). The FI-ICP-MS method results in greater sensitivity and freedom from interferences compared with direct aspiration into an ICP mass spectrometer. Detection limits are improved by approximately a factor of 10. The FI-ICP-MS method is also faster, less labour intensive and generates less laboratory waste than traditional radiochemical methods. The accuracy of the method was tested for 99Tc by comparison to liquid scintillation limits in the soil for 99Tc, 230Th and 234U were 11 mBq/g, (0.02 ng/g), 3.7 mBq/g (0.005 ng/g) and 0.74 mBq/g (0.003 ng/g), respectively. Sample preparation, analysis protocol, and method validation are described.
Technetium-99 Thorium-230 Uranium-234 Mass spectrometry Sample preparation Preconcentration Method comparison Interferences Ultratrace

"Flow Injection Online Sorption Separation And Preconcentration With A Knotted Reactor For Electrothermal Atomic Absorption Spectrometric Determination Of Lead In Biological And Environmental Samples"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 4 Pages 459-464

Abstract: Fish muscle was digested with 65% (w/w) HNO3, the digest was heated with 70% (w/w) HClO4 in a PTFE pressure vessel, the product was evaporated to near-dryness, and the residue was dissolved in water. Soil or sediment was digested with 40% (w/w) HF plus 65% HNO3, the digest was heated with 70% HClO4 in a PTFE pressure vessel, and the product was diluted with water. Diagrams of the flow injection manifold are presented; it incorporated a laboratory-made PTFE knotted reactor (100 cm x 0.5 mm i.d.) on the walls of which the Pb - diethyl phosphorodithioate complex was sorbed at pH 0.5-3.5 before elution with 35 µL of ethanol and transport to a pyrolytically coated GF without platform. The determination was carried out at the same time as the subsequent pre-concentration cycle. An enhancement factor of 125 was achieved, and the detection limit for Pb was 4.8 ng/l. The RSD (n = 11) at 0.5 µg/l of Pb was 2.1%. The results for standard reference materials agreed well with the certified values.
Lead Sample preparation Spectrophotometry Sample preparation Preconcentration Knotted reactor Reference material pH Complexation Solid phase extraction

"Simultaneous Flame Photometric Determination Of Lithium, Sodium, Potassium, And Calcium By Flow Injection Analysis With Gradient Scanning Standard Addition"
Anal. Chem. 1985 Volume 57, Issue 7 Pages 1457-1461
Zhaolun Fang, Joel M. Harris, Jaromir Ruzicka, and Elo H. Hansen

Abstract: A fast-scanning monochromator coupled to a digital oscilloscope was used to obtain analyte emission spectra (from 350 to 800 nm) from an air - acetylene flame. The method was applied to the determination of Na, K and Ca in 1 M ammonium acetate extracts of soil and in tap-water, the coefficient of variation for the metals being 3.9, 3.2 and 4.6%, respectively (n = 11). Addition of Li as an internal standard gave an improvement to 2.5% for Na but did not affect the coefficient of variation for the others. The results agreed closely with those obtained by a conventional flame-photometric method.
Sodium Potassium Calcium Spectrophotometry Gradient technique Internal standard Simultaneous analysis Standard additions calibration

"Comparison Of Continuous-flow And Flow Injection Analytical Techniques For The Photometric Determination Of Traces Of Aluminum In Water And Soil Samples"
Fresenius J. Anal. Chem. 1984 Volume 317, Issue 3-4 Pages 422-426
D. Z&ouml;ltzer und G. Schwedt

Abstract: For the continuous-flow determination of Al, air is added to the stream of test solution from a multi-channel pumping system, then ascorbic acid is added to the sample - air mixture, and, after passage of the resulting mixture through a mixing coil, Chrome Azurol S (C. I. Mordant Blue 29) in aqueous 50% ethanol and acetate buffer are added. After passage through a second mixing coil, the mixture enters a debubbler, and Al is determined in the air-free solution at 546 nm. For flow injection analysis, the sample is injected into a stream of carrier (H2O), ascorbic acid is added, and after passage through a mixing coil, Chrome Azurol S solution in acetate buffer is added. After passage through a second mixing coil, the flowing solution is examined spectrophotometrically at 546 nm. The latter method gives the more symmetrical signals, and its sampling rate and reproducibility are better. The detection limit is ~10 ng mL-1 of Al. The tubing used in either method must be of PTFE (as glass adsorbs Al). In the analysis of soil solution and water, the standard-addition technique must be used.
Aluminum Spectrophotometry Method comparison Standard additions calibration Debubbler

"Element-species Analysis On Soil Solutions By Gel Chromatography And Chemical Reaction Detectors"
Fresenius J. Anal. Chem. 1984 Volume 317, Issue 3-4 Pages 394-399
L. Dunemann und G. Schwedt

Abstract: Gel chromatography (results from 17 gels are compared) was used to fractionate the organic matter in soil equilibrium solution by mol. wt. The fractions so obtained were analyzed for metals in a continuous-flow system (shown diagrammatically) of pumps, reagent additions and a variable-wavelength u.v. detector. The reagent system for Zn was zincon solution at pH 10 (borate buffer) with HCN and chloral hydrate (measurement at 600 nm); for Al (with ascorbic acid present), the reagent was Chrome azurol S (C. I. Mordant Blue 29) in acetate buffer solution (measurement at 546 nm); and for Fe (in presence of mercaptoacetic acid) the reagent was ferrozine solution (measurement at 562 nm). A similar continuous-flow system with chemical-reaction detection was coupled to the gel-chromatographic column to detect functional groups and for metal speciation. Thus, for amino-groups, the reagent was 4-dimethylaminocinnamaldehyde (measurement at 520 nm); for thiols, the reagent was 5,5'-dithiobis-(2-nitrobenzoic acid) (measurement at 412 nm); for hydroxy-groups in acid solution it was 2,2'-bipyridyl, FeCl3 and ethanol (measurement at 525 nm); and for those in alkaline solution, it was 4-nitroaniline (measurement at 483 nm).
Metals Zinc Aluminum Iron Amino acids, thiols GPC Spectrophotometry Speciation

"Flow Injection Analysis In Soil Research And Plant Analysis"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 701-706
K. Schaller, R. Lenhardt, V. Weber und C. Euler

Abstract: Flow diagrams and experimental conditions are given for the determination of N in soils, of NH3 in grape musts and juices, of P in soil extracts, of NO3- in plant extracts and of total amino-acid content, proline and arginine in plants. Each analysis is discussed and compared with other methods.
Nitrogen Phosphorus Nitrate Amino Acids Arginine l-Proline Sample preparation Method comparison Review Tecator

"Determination Of Soil PH By Use Of A Robotic Station"
Fresenius J. Anal. Chem. 1993 Volume 346, Issue 6-9 Pages 704-706
P. Torres, J. A. Garc&iacute;a-Mesa, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: Soil was dried and sieved (2 mm) manually. All other operations were performed by the robotic station, which comprised, inter alia, a Zymate II plus robot, a balance, a dispenser, a pH-measurement electrode and meter, and a PC. Samples (2 g) were weighed into test tubes (10 cm x 1.6 cm), the extractant (H2O or 10 mM CaCl2, 5 ml) was dispensed and the mixture was vortex-mixed for 30 min, during which time other samples were prepared. Each tube was returned to the rack, where a glass-calomel electrode was inserted. The robot arm subsequently washed, rinsed and blotted the electrode ready for the next sample. The throughput was 6 samples/h. Sand, clay and limestone soils and their mixtures gave satisfactory results when compared with manual measurement. The robotic station can also be combined with FIA to automate other soil analyzes.
pH Robot

"Speciation Of Mercury In Soils And Sediments By Thermal Evaporation And Cold Vapor Atomic Absorption"
Fresenius J. Anal. Chem. 1994 Volume 350, Issue 1-2 Pages 18-20
G. Bombach, K. Bombach and W. Klemm

Abstract: Evaporation studies of mercury in several chemical compounds, soils, and sediments with a high content of organic matter indicate that a quantitative release is possible at temperatures as low as 400°C. The desorption behavior from a gold column is not influenced. Only from samples with a thermal prehistory, such as brown coal ash, did mercury evaporate at higher temperatures. Qualitative conclusions can be derived about the content of metallic mercury as well as mercury associated with organic matter or sulfide. A comparison of the analytical results obtained by using the evaporation technique or by dissolving using a mixture of concentrated HCl and HNO3 shows good agreement; the advantages of the evaporation technique are obvious at very low mercury concentrations.
Mercury Sample preparation Spectrophotometry Volatile generation Heated reaction Speciation Volatile generation

"Limitations Of A Laboratory Robot For Extracting Available Nutrients From Soil"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 1 Pages 77-80
N. Brenes, A.M. Bunnell, P.A. Langan, M.N. Quigley, W.S. Reid

Abstract: Soil (2 ml) and 0.2 mL of activated charcoal were transferred to borosilicate glass test tubes (15 cm x 2.5 cm i.d.) by hand, placed in one of four racks of 40. The Zymate II weighed the samples, added 10 mL of acetate buffer of pH 4.8 (Morgan's reagent), vortex-mixed the tubes for 30 s at a setting of 100 units and centrifuged the mixtures. The supernatant liquids were analyzed for phosphate and nitrate by continuous-flow colorimetry and for Al, Ca, Fe, Mg, Mn, K and Zn by the sample volume to 3, 4, 5 and 6 ml, while maintaining the same sample/reagent ratio, were studied. The vortexing step was unchanged, but, for comparison, in another set, the solutions were mixed by hand with a glass rod during a pause. These procedures were applied to a reference soil sample. For all analytes, the maximum extraction by vortexing was obtained with the standard 2 mL sampling; with larger volumes, the amount extracted dropped to half or less. In theory, hand mixing should give results independent of sample volume and this was approximately the case for some analytes (nitrate, phosphate, Ca, K, Mg) but not all. The implications of these findings are discussed briefly.
Phosphate Nitrate Aluminum Calcium Iron Manganese Potassium Zinc Spectrophotometry Sample preparation Extraction Robot

"Determination Of Low Amounts Of Platinum In Environmental And Biological Materials Using Thermospray Nebulization Inductively Coupled Plasma-mass Spectrometry"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 5-6 Pages 664-667
M. Parent, H. Vanhoe, L. Moens and R. Dams

Abstract: Freeze-dried urine (SRM 2670), plant tissue, and soil or dust (0.1 g) were decomposed with HNO3, HNO3/HClO4 or HNO3/HClO4/HF, respectively. The solutions were heated with aqua regia then HNO3 was removed by evaporation. SnCl2 was added to convert the Pt(IV) to Pt(II). The resulting bis(carboxymethyl)dithiocarbamate complex of Pt(II) was adsorbed on to XAD-4 resin, then back-eluted with ethanol (idem, Biol. Trace Elem. Res., 1994, 43-45, 109). The ethanol was evaporated and the residue was dissolved in 0.5 mL 0.14 M HNO3 containing IR as internal standard. This procedure separated Pt from most matrix elements including Hf. Portions (0.1 ml) were introduced by flow injection into a thermospray nebulizer and the Pt was determined by ICP-MS. Recoveries were variable (from 62-102%) so isotope dilution was carried out with a 194Pt-enriched Pt sponge before the decomposition. The detection limit was 1 pg absolute. The results compared well with those obtained by other methods, e.g., electrothermal AAS or NAA and the certified value.
Platinum Platinum-194 Sample preparation Mass spectrometry Mass spectrometry Reference material Method comparison

"Flow Injection Determination Of Lead By Hydride Generation And Conductometric Detection"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 2 Pages 141-143
P. C. Hauser and Zhi-Ping Zhang

Abstract: Plumbane produced from the lead analyte in a flow injection manifold by reaction with sodium borohydride is passed through a porous poly(tetrafluoroethylene) membrane in a gas diffusion cell. The hydride reacts with bromine in the acceptor stream resulting in ionization which is detected by conductivity measurement. Direct mixing of the carrier with a reagent stream yields a limit of detection of approximately 1 mg/L. An improved detection limit of about 200 µg/L can be achieved by the incorporation of an auxiliary stream containing persulfate as oxidizing agent. The application of the method to the determination of lead in road dust and soil samples is demonstrated. The flow injection method was based on the reaction of PbH4 with Br2 to yield bromide ions which were detected by conductivity measurement. A sample of 75 µL was injected into a 0.04 M HNO3 carrier stream which was merged with the reagent stream, 0.3% NaBH4 in 0.05% NaOH. After passing through a reaction coil (60 cm x 0.5 mm i.d.), the flow was propelled to the gas diffusion cell where the liberated PbH4 diffused through a PTFE membrane and was collected in a 0.6 mM Br2 acceptor stream. The acceptor stream was propelled to the conductivity detector where the ionization was detected. All flow-rates were 0.3 ml/min. The calibration graph for Pb was linear for 2-12 mg/l, the detection limit was 1 mg/l and RSD (n = 5) were 3%. The method was applied to the determination of Pb in urban road dust and soil following sample preparation by a standard acid digestion procedure. The results were in agreement with those obtained by AAS.
Lead Conductometry Sample preparation Spectrophotometry Gas diffusion Teflon membrane Method comparison

"Determination Of Selenium In Soil By Hydride Generation AAS"
Fresenius J. Anal. Chem. 1998 Volume 360, Issue 2 Pages 225-229
V. Kos A, Marjan Veber A, Vida Hudnik

Abstract: Hydride generation AAS was applied for the determination of total selenium in soil. The influence of various anions and cations present in the sample solution on the generation of selenium hydride was investigated. Special attention was paid to the wet oxidation procedure for the sample dissolution. The proposed procedure involves microwave sample preparation by using a mixture of H2O2/HNO3/H2SO4. The accuracy of the procedure was checked by the analysis of the standard reference material Buffalo River Sediment (SRM-2704, NIST). Satisfactory agreement of the results obtained with the values reported was achieved. The detection limit of the procedure was 25 ng Se/g of soil. The relative standard deviation of the measurements varied from 5.5% for SRM-2704 up to 10% for the real soil samples.
Selenium Spectrophotometry Volatile generation

"The Effect Of Sample Preparation On Metal Determination In Soil By FAAS"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 1 Pages 125-129
Zofia Kowalewska A, E. Bulska A, A. Hulanicki

Abstract: Different methods for the determination of several metals in soils by flame atomic absorption spectrometry (FAAS) were investigated. Different procedures for total dissolution of soil: I - HF+HClO4, H3BO3, HCl digestion (conventional heating), II - HF+HClO4, H3BO3 digestion followed by fusion with LiBO2 (conventional heating) and III - HF+HCl+HNO3, H3BO3 digestion (microwave heating), as well as a leaching procedure with HNO3+HClO4, HCl were tested and compared. For quality assessment, the certified reference material S-1 soil was used. For most of the investigated metals, the best accuracy and precision were achieved when the procedure I or III were used. The developed procedure was applied to the analysis of soil samples from crude oil refinery and dump of petroleum origin wastes regions.
Spectrophotometry Sample preparation

"Flow Injection Analysis Of Zinc And Cobalt In Beverages, Biological, Environmental, And Pharmaceutical Samples"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 7-8 Pages 571-576
S. G. Aggarwal and K. S. Patel

Abstract: A new, simple, rapid, and selective flow injection analysis (FIA) method for the spectrophotometric quantification (speciation of inorganic and organic form) of Zn and Co with NH4SCN and malachite green (MG) in the presence of surfactants (CPC and TX-100) is described. The value of apparent molar absorptivity of the Zn- and Co-complexes are 1.23 x 104 and 8.67 x 103 L mol-1 cm-1 at absorption max., 635 nm, respectively. The detection limit (amt. causing a peak height >3 s) is 15 ppb Zn and 20 ppb Co, whereas their optimum working ranges for the quant. determinations are 0.05-2.0 ppm Zn and 0.07-2.5 ppm Co in the real samples. The sample throughput of the method is 120 samples/h at the flow rate of 5.0 mL/min with RSD of <1%. The method is free from interferences of almost all ions which are commonly associated with these metals in the complex materials. The composition of the complexes and their reaction mechanism involved are discussed. The effect of FIA and anal. variables for the determination of the metals are optimized. The method was applied to the quantification of Zn and Co in beverages, biol., environmental, and pharmaceutical samples.
Zinc Cobalt Spectrophotometry Speciation pH gradient Surfactant Interferences Complexation

"Speciation Of Antimony By Atomic Absorption Spectrometry. Applicability To Selective Determination Of Antimony(III) And Antimony(V) In Liquid Samples And Of Bioavailable Antimony In Sediments And Soil Samples"
Microchim. Acta 1992 Volume 109, Issue 1-4 Pages 149-155
Mar&iacute;a Beatriz de la Calle Gunti&ntilde;as, Yolanda Madrid and Carmen C&aacute;mara

Abstract: Speciation of Sb(III) and Sb(V) by AAS in liquid samples was evaluated by investigating the (i) determination of Sb(III) and SbV in water by selective extraction with lactic acid - malachite green by graphite-furnace AAS; (ii) determination of Sb(III) and Sb(V) by hydride-generation - AAS coupled to flow injection, batch and continuous-flow systems; (iii) mineralization methods for soil samples. Different sample pre-treatments were evaluated in terms of recovery of total Sb and the ability to speciate Sb(III) and SbV by slurry formation in soil and sediments. The graphite-furnace extraction method was the most convenient method for speciation of Sb(V) and Sb(III) in surface and seawater.
Antimony(3+) Antimony(5+) Spectrophotometry Spectrophotometry Speciation Slurry

"Atomic Absorption Spectrometric Determination Of Mercury In Soil Standard Reference Material Following Microwave Sample Pretreatment"
Microchim. Acta 1995 Volume 119, Issue 1-2 Pages 137-146
Ewa Bulska, Wolfgang Kandler, Piotr Paslstrokawski and Adam Hulanicki

Abstract: Various decomposition methods were compared for the determination of Hg in soil reference material by ETAAS and flow injection cold vapor AAS. Open and closed vessel microwave digestion using 1 M HCl, concentrated HNO3 or aqua regia and digestion under reflux according to the German standard method were used (details given). The temperature program for ETAAS is tabulated; Hg was determined at 253.7 nm with background correction and use of Pd as modifier (details given). For cold vapor AAS, samples were reduced with SnCl2 or NaBH4 and Hg vapors were stripped with Ar and transferred to the absorption cell of the Perkin Elmer FIAS-100 or FIMS systems used. ETAAS was suitable for soil containing 6.25 µg/g Hg. For open microwave digestion with HCl recoveries were 89-98% and RSD were 1-3%. HNO3 decreased the sensitivity. Cold vapor AAS was suitable for lower Hg concentrations. The use of NaBH4 was preferred since the signal did not depend on acid concentration and type. Digestion with HCl or aqua regia was suitable. Calibration graphs using standard additions were linear for 2-20 µg/l Hg and the recoveries were 97-102%.
Mercury Spectrophotometry Spectrophotometry Sample preparation FIAS-100 FIMS Reference material Standard additions calibration

"Spectral And Non-spectral Interferences In Inductively Coupled Plasma Mass Spectrometry"
Microchim. Acta 1995 Volume 119, Issue 3-4 Pages 277-286
Richard F. J. Dams, Jan Goossens and Luc Moens

Abstract: An overview is presented on the identification and elimination of interferences in ICP-MS. Elimination of spectral interferences by anion exchange, matrix modification and mathematical correction are discussed. Calibration methods, adapted sample preparations and flow injection techniques for the elimination of nonspectral interferences are then considered. Applications of the correction methods to the analysis of water, soil, sewage, urine, serum and wine are described. (50 references).
Mass spectrometry Sample preparation Interferences Matrix removal Review

"Kinetic Flow Injection Spectrophotometric Determination Of Nitrite By Its Catalytic Effect On The Oxidation Of Chlorophosphonazo-pN By Bromate"
Anal. Lett. 1996 Volume 29, Issue 11 Pages 2015-2023
Chen Xingguo; Wang Ketai; Hu Zhide; Zhao Zhengfeng

Abstract: Sample (120 µL) was injected into the carrier stream (H2O; 0.8 ml/min) and mixed in a mixing coil (12 cm length) with 2-(4-chloro-2-phosphonophenylazo)-7-(4-nitrophenylazo)-1,8- dihydroxynaphthalene-3,6-disulfonic acid/H2SO4 (0.8 ml/min). The resulting stream was merged with 6 mM KBrO3 (1-2 ml/min) in a reaction coil (100 cm length) at 80°C. The resulting decrease in absorbance was monitored with a 1 cm path flow cell at 551 nm. The sampling frequency was 83 samples/h. The calibration graph was linear from 0.05-1 µg/ml of nitrite with a detection limit of 0.018 µg/ml. Chloride interference could be removed by precipitation with AgNO3. The RSD (n = 7) was 1% at the 1 µg/ml level (based on peak height). The method was applied to the determination of nitrite in water and soil.
Nitrite Spectrophotometry Catalysis Interferences Heated reaction Kinetic

"Determination Of Total Mercury In Soils, Waste-water And Sewage Effluents"
Anal. Lett. 1997 Volume 30, Issue 8 Pages 1579-1590
M. T. M. Zaki; M. A. Esmaile

Abstract: The cationic mercury(II)-1,10-phenanthroline binary chelate reacts with the acidic dye Thymol Blue (TB), in the pH range 5.2-7.0, to form an ion-pair extractable into chloroform. The effect of primary ligand and counter ion concentrations, pH, extraction solvent, extractability, standing time and co-existing ions has been thoroughly investigated. The molar absorptivity of the ion-pair, in chloroform, is 1.27 x 10(5) L mol-1 cm-1 at 420 nm. The calibration graph is rectilinear for 0.09-1.72 µg mL-1 of mercury. The sensitivity index of the method is 0.0002 µg Hg cm-2 and the detection limit is 0.018 µg mL-1 of mercury. The stoichiometry of the extracted ion-pair is 1:2:1 (Hg-Phen-TB). The developed method has been successfully used to determine total mercury in soils, waste water and sewage effluents. 23 References
Mercury Spectrophotometry Sample preparation Chelation Ion pair extraction Organic phase detection

"Flow Injection Potentiometric Determination Of Atrazine In Herbicide Formulations"
Anal. Lett. 1998 Volume 31, Issue 5 Pages 777-791
Saad S. M. Hassan; M. N. Abbas; G. A. E. Moustafa

Abstract: A novel atrazinium-selective membrane sensor consisting of an atrazine phosphomolybdate ion-pair complex dispersed in a PVC matrix plasticized with dioctyl phthalate is described and electrochemistry evaluated under static and hydrodynamic modes of operation. The sensor is incorporated in a flow-through sandwich cell and used as a detector for flow injection determination of atrazine herbicide. The intrinsic characteristics of the detector in a low-dispersion manifold are determined and compared with those of a conventional-shaped sensor. In a phosphate buffer of pH 5, the detector exhibits a rapid near-Nernstian response (52.3 mV/decade) for atrazinium cation over the concentration. range 10^-2-10-5M. Concentrations as low as 0.3 µg atrazine/mL can be detected with an average recovery of 98.3% (mean standard deviation 0.6%), and the sample input rate is 60 sample per h. The sensor is used for determining atrazine in herbicide formulations, and in extracts of water and soil. No interferences are caused by herbicide diluents and excipients nor by most common anions and cations normally present in water and soil. The results compare favorably with data obtained by gas chromatography
Atrazine Potentiometry Electrode Electrode Electrode Sample preparation Interferences Method comparison

"New Approaches To Coupling Flow Injection Analysis And High Performance Liquid Chromatography"
J. Chromatogr. A 1992 Volume 600, Issue 2 Pages 183-188
M. D. Luque de Castro* and M. Valc&aacute;rcel

Abstract: In pre-column arrangements (A), the flow injection system is placed before the LC column, whilst in post-column couplings (B), the chromatographic process takes place before the flow injection analysis. In each instance the downstream unit incorporates the detection module. Examples of the use of A include: the determination of Zn based on its activating effect on metal-free carboxypeptidase A immobilized in a controlled-pore-glass reactor; the coupling of a liquid - liquid extractor to a normal-phase chromatograph for the determination of caffeine in beverages and urine; and the coupling of an ultrasonic leaching cell for solid - liquid extraction processes such as in the determination of B in soil. Only those B systems incorporating two valves are considered to be true HPLC - flow injection analysis configurations. Examples of the use of B include: determination of aflatoxins in foodstuffs, based on enhancing their fluorescence by means of a redox reaction with Br; and the determination of bile acids, based on the production of NADH. A review with 15 references. An overview of the advantages gained in coupling a flow injection manifold to a liquid chromatograph is presented. Improvements in the analytical features arising from this association and the peculiar pre- and post-column arrangements are discussed, as are the promising prospects of arrangements to be developed for avoiding the preliminary steps of the analytical process.
Caffeine HPLC Post-column derivatization Pre-column derivatization Immobilized enzyme Controlled pore glass Review

"Normal-phase High Performance Liquid Chromatography With UV Irradiation, Morin Complexation And Fluorescence Detection For The Determination Of Organotin Pesticides"
J. Chromatogr. A 1992 Volume 609, Issue 1-2 Pages 195-203
Joan A. St&auml;b, Marcel J. M. Rozing, Bert van Hattum and Wim P. Cofino, and Udo A. Th. Brinkman

Abstract: Surface waters were extracted with n-hexane, while soil and sediments were Soxhlet-extracted for 12 h with hexane - acetone (9:1). The extracts were analyzed on a column (15 cm x 4.6 mm) of cyanopropyl-bonded silica (3 µm) with n-hexane - THF - acetic acid (48:1:1) as mobile phase (1 mL min-1). Post-column derivatization was effected by UV irradiation followed by reaction with ethanolic 0.0025% morin (0.15 mL min-1) in a reaction coil and fluorimetric detection at 495 nm (excitation at 430 nm). The detection limits were 0.02 to 0.03 µg L-1 in water and 0.2 to 0.3 µg g-1 in solids. The mean recoveries from water were between 61 and 114% and from the solids between 44 and 135% for three such compounds.
Tin, organic HPLC Fluorescence Sample preparation Post-column derivatization Complexation

"High Performance Liquid Chromatographic Method For The Analysis Of Aminocarb, Mexacarbate And Some Of Their N-methylcarbamate Metabolites By Post-column Derivatization With Fluorescence Detection"
J. Chromatogr. A 1994 Volume 672, Issue 1-2 Pages 117-124
K. M. S. Sundaram* and J. Curry

Abstract: Water and soil were extracted with CH2Cl2 and ethyl acetate, respectively, the extracts were dried with Na2SO4, flash evaporated at 30°C, the residue was dissolved in acetonitrile and partitioned twice with hexane. The polar layer was flash evaporated, dissolved in ethyl acetate, concentrated under N2 and cleaned up on alumina with elution by ethyl acetate containing 0 and 10% methanol. After evaporation to dryness, the residue was dissolved in acetonitrile for analysis by HPLC on a column (20 cm x 4.6 mm i.d.) of HP RP-8 OS (10 µm) at 30°C with a guard column (3 cm x 4.6 mm i.d.) of HP RP-8 (10 µm), a gradient mobile phase (1 ml/min) of aqueous 0-30% acetonitrile over 25 min, then to 50% (held for 10 min) over 10 min, post-column derivatization by hydrolysis with 50 mM NaOH in a 1 mL reaction coil at 95°C, reaction with o-phthalaldehyde/2-mercaptoethanol in a 0.5 mL reaction coil at 40°C and fluorimetric detection at 418 nm (excitation at 230 nm). Calibration graphs were linear for 0.1 (detection limit) to 500 ng of aminocarb, mexacarbate and four carbamate metabolites; recoveries from water (2 and 20 ng/ml) and soil (20 and 200 ppb) were 72±7.9% to 98.4±5.2% with RSD of 5-11.5%.
Aminocarb Mexacarbate Carbamates, N-methyl HPLC Fluorescence Post-column derivatization Heated reaction

"Changes In Soil PH And Exchangeable Base Cations During Moist Soil Storage"
Anal. Proc. 1995 Volume 32, Issue 11 Pages 467-470
Eltijani A. Elias and Malcolm S. Cresser

Abstract: The changes in selected soil chemical properties viz. pH, cation exchange capacity (CEC) and exchangeable base cations (Ca, Mg, K and Na) over three months was investigated for four moorland soils collected from the A, E, B and C horizons of a typical podzol profile of the Counteswells Series cf. Glenworth and Muir (The Soils of the Country Round Aberdeen, Inverurie and Fraserburgh, 1963, HMSO, Edinburgh, 371). Each soil was sieved through a 2 mm mesh and sixteen 30 g portions of sieved soil from each horizon was transferred to plastic jars. Moisture contents of each were maintained at 162, 62, 66.6 and 25.5%, respectively, for the A, E, B and C soils, by adding appropriate amounts of water weekly to retain the 30 g mass. Half the samples were stored at 4°C and half at room temperature. After 1, 2 and 3 months, a 5 g portion of soil was treated with 250 mL 1 M ammonium acetate at pH 7 and the solution was analyzed for Ca and Mg and K and Na by AAS and spectrophotometry, respectively, (details given). For CEC, the soils were further washed with 250 mL 80% ethanol and the absorbed NH+4 was leached with acidified NaCl and determined by flow injection spectrophotometry. Significant changes in CEC, pH and exchangeable cation concentrations within one month were observed and the changes increased on more prolonged storage. The magnitude of change depended upon the soil horizon and the analysis method involved.
Ammonium Calcium Magnesium Potassium Sodium Spectrophotometry Spectrophotometry Sample preparation

"A Method Using Peroxydisulfate Digestion For Total N Analyses In Soils And In Soil Microbial Biomass Extracts"
Acta Agri. Scand. B 1996 Volume 46, Issue 2 Pages 81-85
Finn Eiland and Jrgen Dissing Nielsen

Abstract: The persulfate oxidation (TPM) and the Kjeldahl methods (TKN) were compared for measurement of total N in soils and soil extracts. The TPN method was adapted for optimum recovery and precision in the determination of total N. Measurement of total N with TPN and TKN procedures showed the methods to be comparable for both mineral soils and soil extracts. For soil samples with a high content of C and N ( gt 0.5%), the total N content was highest with TKN. The Flow Injection Analysis (FIA) was very suitable for analysis of nitrate in persulfate digestions. The TPN method combined with FIA estimation of nitrate is recommended for analysis of total N in soils and in soil extracts for microbial biomass determinations.
Nitrogen, total Sample preparation Sample preparation Optimization Kjeldahl

"Determination Of Phosphorus (blue Method) In Undiluted Soil Extracts By Flow Injection Analysis"
Landwirtsch. Forsch. 1990 Volume 43, Issue 2 Pages 128-130
Ketschau, U.; Schmid, R

Abstract: An automated method for the determination of phosphorus in soil by flow injection analysis is described. Although the method uses the molybdophosphoric blue reagent, concentration of up to 75 ppm P2O5 can be measured, and it is not necessary to dilute the soil extract.
Phosphorus Sample preparation Spectrophotometry Tecator

"Simultaneous Determination Of Nitrites And Nitrates By Flow Injection Analysis"
Agrochemia 1988 Volume 28, Issue 4 Pages 119-122
Karlicek, R.;Dolejsova, J.;Polasek, M.

Abstract: The method involves the reaction of NO2- with sulfanilamide and N-(1-naphthyl)ethylenediamine in acid solution, with absorbance measurement of the red dye. Nitrite (0.02 to 2 mg l-1) was determined directly in extracts of feed, food or soil; NO3- (0.5 to 20 mg l-1) was determined in the same sample after reduction by metallic Cd. Automated analysis of 45 samples h-1 was possible.
Nitrite Nitrate Sample preparation Spectrophotometry Simultaneous analysis

"Determination Of Ammonium Nitrogen In Water And Soil By Flow Injection Analysis"
Agrochemia 1991 Volume 31, Issue 4 Pages 87-90
Solich, P.;Cap.P.;Karlicek, R.

Abstract: NA
Ammonium, nitrogen

"Determination Of Boron In Plants, Soils And Waters By Flow Injection Analysis"
Analusis 1988 Volume 16, Issue 9-10 Pages 196-200
Lopez Garcia, I.;Sanchez Pedreno, C.;Hernandez Cordoba, M.;Garcia Lorente, A.

Abstract: The method described earlier (cf. Anal. Abstr., 1986, 48, 6D31), involving spectrophotometry of the ion-pair complex between crystal violet (C. I. Basic Violet 3) and the anionic B - 2,6-dihydroxybenzoic acid complex without extraction, has been adapted for flow injection analysis, both conventional, with measurement at 490 nm, and in reverse mode, with injection of the dye reagent into a stream of the anionic complex solution and measurement at 590 nm. The rectilinear ranges of the respective methods are 0.02 to 0.5 and 0.05 to 0.5 µg mL-1 of B. Plant samples are mixed with Ca(OH)2 and dry-ashed, the ash is extracted with 0.5 M H2SO4 and the solution is neutralized before analysis. Soil is extracted with water at 80°C. Water is adjusted to pH 2 to 3 with H2SO4 on collection. Tolerance levels for a range of foreign ions are tabulated.
Boron Sample preparation Spectrophotometry Complexation Interferences Reverse

"Determination Of Available Nitrogen (nitric And Ammoniacal) In Soils By Flow Injection Analysis"
Analusis 1992 Volume 20, Issue 8 Pages 483-487

Abstract: Finely ground soil (40 g) was extracted with 2 M KCl (200 ml) containing phenylmercuric acetate (5 mg l-1) before flow injection analysis. For ammoniacal N, the sample was mixed with 70 µM-NH4Cl before reaction with 50% Nessler's reagent prepared according to Krug. The absorption of the reaction solution was measured at 415 nm. For nitric N, sample was merged with 0.1 M NH4Cl and the nitrites formed were reacted with acidic sulfanilaminde and N-(1-naphthyl)-ethylenediamine dihydrochloride. The absorbance of the purple azo dye formed was measured at 540 nm. Total N was calculated by the sum of the results obtained. Calibration graphs were rectilinear for 0.02 to 4 and 0.10 to 8 ppm of ammoniacal and nitric N, respectively. The coefficient of variation were 1.34% and recoveries were 104.5%. Results were in good agreement with those obtained by the reference method (cf. Puchades et al., Plant Soil, 1984, 78, 357). Ammonium- and nitric-N (NO3- + NO2-) were determined in KCl extracts of soils by flow injection analysis (FIA) with spectrophotometric detection at 415 and 540 nm, respectively. For ammonium-N (Nam) a reverse FIA system based on the Nessler reaction was developed. Nitric-N (Nn) was determined with a cadmium reductor column which reduces the nitrates to nitrites online, using a normal FIA system. The nitrites were reacted with acidic sulfanilamide and N-(1-naphthyl)-ethylenediamine dihydrochloride to give a purple azo dye. The results obtained for Nam, Nn and total N by these new methods are in good agreement with those obtained by the reference method (Puchades, R., 1984), as the excellent correlation coefficients indicate. Sampling frequency was 40/h (in duplicate), and the precision was better than 1.34% (Nam) and 0.55% (Nn) for 15 replicate measurements.
Nitrogen, ammonia Nitrogen, nitrate Nitrogen, nitrite Nitrogen, total Sample preparation Spectrophotometry Method comparison Reduction column Reverse

"Colorimetric Determination Of Available Iron In Soils By Flow Injection Analysis"
Analusis 1996 Volume 24, Issue 8 Pages 343-346
AMR Ferreira, JLFC Lima, AOSS Rangel

Abstract: A method is presented based on formation of the Fe(II)-1,10-phenanthroline complex in aqueous solution. A large injection volume was used to eliminate RI interferences. Soil was extracted with ammonium acetate using a standard method then 540 µL was injected into a stream of 1 ml/min water in a FIA system constructed from PTFE tubing (0.8 mm i.d.) and acrylic Y-shaped joints. After mixing with 0.01% ascorbic acid at a flow rate of 1 ml/min in 1.2 M HCl in a 15 cm coil, the stream was mixed at a flow rate of 2 ml/min with 0.01% 1,10-phenanthroline in 1.5 M sodium acetate in a 200 cm coil. Absorbance was measured at 508 nm at the central plateau in the detector signal. The detection limit was 0.07 mg/l Fe. RSD were 0.82-1.72% (n = 10) for 1.55-5.14 mg/l Fe. The method could be applied to 60 samples/h; when applied to 20 samples, results agreed with those of a standard reference method.
Iron Spectrophotometry Interferences Standard method Method comparison

"Determination Of Nitrite, Nitrate And Ammonium Nitrogens In Soil By FIA"
Bunseki Kagaku 1989 Volume 38, Issue 9 Pages 413-418
Shirato, F.;Okajima, Y.;Maekoya, C.;Takata, Y.

Abstract: For determination of NO2-, N-(1-naphthyl)ethylenediamine reagent (40 µL) was injected into water (carrier solution) on either side of the sample solution by using a 16-port injection valve. The stream was passed to a PTFE reaction coil (10 m x 0.5 mm) operated at 90°C, and the absorbance was measured at 520 nm. Nitrate was determined similarly after its reduction to NO2- on a glass column (30 cm x 3 mm) of Cu - Cd (0.5 to 2 mm). For NH4+-N, NH3 was liberated by 1 M NaOH (200 µL) injected on both sides of the sample solution, separated with use of a tubular microporous PTFE membrane and determined by the indophenol method. Absorbance was measured at 630 nm. Beer's law was obeyed for 0.1 to 7, 1 to 20 and 1 to 150 ppm of NO2-, NO3- and NH4+-N, respectively. The coefficient of variation were 0.3 to 0.5%. The analysis time was 10 min per sample.
Ammonium, nitrogen Nitrite Nitrate Spectrophotometry Valve Glass Column Heated reaction Teflon membrane

"Online Sample Preparation With Flow Injection Analysis: Avoiding Additional Preparation Steps"
Chem. Rundsch. 1987 Volume 40, Issue 11 Pages 11-NA
Winter, B.

Abstract: As illustrated by the determination of NH4+ and of surfactants, it is shown that single stages or the entire sample preparation can be integrated by use of flow injection analysis. Problems of the matrix in determining NH4+ in, e.g., waste water, soil extracts or acid digests of food are discussed; the NH4+ can be separated from the matrix by gas diffusion from NaOH medium into a receptor stream for photometric detection. Surfactants can be separated from environmental, food or pharmaceutical samples by liquid - liquid ion-pair extraction into CHCl3, with use of a PTFE membrane as phase separator and photometric detection. Flow diagrams for these analyzes are presented.
Ammonium Surfactants Sample preparation Spectrophotometry Gas diffusion Online digestion Ion pair extraction Phase separator Teflon membrane Tecator

"Techniques For Preserving And Determining Aluminium Fractions In Soil Solution From Podzolic Forest Soils"
Chemosphere 1998 Volume 36, Issue 4-5 Pages 1143-1148
Kirsti Derome, John Derome and Antti-Jussi Lindroos

Abstract: The purpose of the study was 1) to determine techniques for minimizing the effects of transportation and storage on the concentrations of different Al fractions in soil solution samples, and 2) to determine a suitable method for analyzing monomeric Al concentrations in water samples from humus-rich podzolic soils. Aluminium fractionation was performed on a cation exchange column and the fractions were analyzed by ICP/AES and FIA. A time lag of a few hours to two days between sampling and pretreatment appeared to have no effect on total Al concentrations, even though the samples were not preserved with acid. Freezing the samples was not an appropriate storage technique because it resulted in a strong decrease in total Al concentrations. Storage (+4°C) had a detrimental effect on the proportion of exchangeable monomeric Al, but this problem was overcome by fractionating the samples immediately on arrival at the laboratory. Adjustment of sample pH to <3.7 permitted storage of the fraction for at least 2 weeks before analysis by ICP/AES or FIA. Either of these two techniques can be used for determining exchangeable monomeric Al, but if the non-exchangeable reactive Al fraction (i.e. organically complexed Al) is required then analysis by FIA is necessary.
Aluminum, labile Sample preparation

"Establishment And Analytical Quality Control Of Laboratories For Hg Determination In Biological And Geological Samples In The Amazon, Brazil"
Cienc. Cult. 1998 Volume 50, Issue 4 Pages 255-260

Abstract: During the past 20 yr significant amounts of Hg were released in the Amazonian environment due to gold mining activities. Several Brazilian and foreign research groups were studying the region, always facing difficulties regarding preservation and transfer of the collected samples from the field to the anal. labs. Aiming to solve these problems two high quality Hg anal. labs. were established in the region. One is located at Fundacao Esperanca (FE, Santarem, PA), a medical assistance foundation and the other at the Universidade Federal de Rondonia (UNIR), Porto Velho, RO. Their main equipment is: Atomic absorption spectrophotometers for Hg anal. (Flow Injection Mercury System-FIAS 400 with automatic samples-AS90-Perkin Elmer) and a microwave oven digestion system (MDS-2000-CEM). Technicians and researchers were trained in several aspects like environmental and human sampling, digestion methods and Hg anal. for biotic and abiotic materials. This training as well as the installation of the mentioned labs. were the responsibility of the Universidade Federal do Rio de Janeiro (UFRJ). Intercalibration exercises were performed between several labs.: Environmental Medicine of Odense University (Denmark), Center de Toxicologie du Quebec, Canada and Occupational Health Sciences (Health-Canada). In the last 18 mo the FE lab. joined the Hg urine anal. intercalibration program of the Lab. of the Center of Toxicol. in Quebec, Canada, reaching accurate results. To date both Amazonian labs. are able to analyze several different materials: Sediment, soil, fish, urine, hair and blood. The FE lab. is becoming more specialized in human samples such as urine, blood and hair, while UNIR lab. deals with environmental samples such as fish, sediment and soil.
Mercury Spectrophotometry Sample preparation FIAS-400 FIMS

"Determination Of Ultratrace Amounts Of Selenium(IV) In Water And Soil Extracts By Flow Injection Online Ion-exchange Preconcentration Hydride Generation Atomic Absorption Spectrometry"
Kexue Tongbao 1990 Volume 35, Issue 6 Pages 526-527

Abstract: Sample solution (9 mL min-1) was merged with 0.2 M acetate buffer (pH 5; 0.5 mL min-1) before passing through a column (4.5 cm x 3 mm) of D201 macroporous anion exchanger (50 mesh). Selenium was eluted with 1 M HCl (6 mL min-1) and the eluate was mixed with 0.5% of NaBH4 in 0.1% NaOH solution (2 mL min-1). The SeH4 was separated in a gas - liquid separator and carried by Ar (150 mL min-1) to a silica atomizer heated at 700°C for determination by AAS at 196.0 nm. The detection limit was 2 ng l-1, and the sampling rate was 50 h-1. The coefficient of variation were 1.1% (n = 11) for 0.5 µg L-1 and 6.4% (n = 10) for 0.01 µg l-1. Recoveries from tap, well and mineral waters were 96 to 100% and from soil extracts were 92 to 102%.
Selenium(IV) Ion exchange Spectrophotometry Clinical analysis Sample preparation Preconcentration Buffer pH Phase separator Detection limit Ultratrace Volatile generation

"Conductometric Determination Of Soil Urease Activity"
Commun. Soil Sci. Plant Anal. 1984 Volume 15, Issue 11 Pages 1377-1389
U. Gosewinkel; F. E. Broadbent

Abstract: After incubation of the soil with urea solution, ammonium-N was extracted into 1 M KCl - 0.01 M HCl in several stages, and NH4+ was determined by measurement of electroconductivity in a continuous-flow instrument. Air was mixed into the sample stream, which was then passed through a permeation unit that allowed NH3 to diffuse at steady state through a membrane into a stream of de-ionized water running into a conductivity cell. Sampling was carried out automatically from the extracts at 40 samples h-1. The detection limit for ammonium-N was <0.05 ppm in the extract. Urea was not hydrolyzed chemically during the experimental procedure, or after storing for 17 h at room temperature A background of 5000 ppm of urea-N did not interfere with NH4+ determination. The method was applicable in investigations of salinity effects on soil urease activity.
Enzyme, urease Conductometry Interferences Membrane Steady state

"Rapid Determination Of Nitrate At Low Concentrations In Soil Extracts: Comparison Of Ion-selective Electrode With Continuous-flow Analysis"
Commun. Soil Sci. Plant Anal. 1984 Volume 15, Issue 12 Pages 1437-1451
Shengxiu Li; K. A. Smith

Abstract: The efficiency of extraction of nitrate with saturated CaSO4 solution and with 1 M KCl was compared for a range of field-moist and air-dried soils. Saturated CaSO4 was as effective for moist soils and slightly more effective for dried ones, and removed 95% of the nitrate after shaking for 5 min. Three methods of nitrate analysis using an ion-selective electrode were compared with continuous-flow analysis (CFA). All gave good correlations with CFA but only one, a 'known addition' method, gave results which agreed quantitatively.
Nitrate Electrode Sample preparation

"Chloride Analysis Of Soil Leachate Using The TRAACS 800 Analyzer"
Commun. Soil Sci. Plant Anal. 1990 Volume 21, Issue 13-16 Pages 1689-1693
Tel, D.A.;Heseltine, C.

Abstract: Soil samples were extracted with 0.1 M NaNO3, 0.1 M HNO3 or water by shaking for 10 min or setting the solution aside overnight. The extract was passed through a 12-in. dialyser to remove interferents before continuous-flow reaction with Hg(SCN)2, methanol, HNO3 and Fe(NO3)3 and measurement of Fe(SCN)3 formed at 480 nm. Calibration graphs were rectilinear from 4 to 400 and 40 to 4000 mg L-1 of Cl-. The coefficient of variation (n = 30) was 0.34% at 100 mg of Cl- and 0.30% at 1 g L-1 of Cl-.
Chloride Dialysis Interferences Calibration

"Simple Manual Method For The Determination Of Phosphate-extractable (ion-exchange Membrane) Sulfate In Soils"
Commun. Soil Sci. Plant Anal. 1991 Volume 22, Issue 13-14 Pages 1347-1354
Searle, P.L.

Abstract: Air-dried soil (2.5 g) was placed in a stoppered tube with 10 mL of water and a strip (4 cm x 4 mm) of an anion-exchange membrane (B.D.H. Cat. No. 55164) which had been washed with 0.5 M H3PO4 (5 x 100 ml). The tube was shaken at 50 rpm for 16 h at 20°C before the strip was removed, rinsed with water and immersed in 25 mL of 0.5 M H3PO4. After 3 h, the membrane strip was removed and a 25 mL portion of the remaining solution was mixed with 1 mL of sulfate seed solution (30 mL of concentrated H3PO4, 800 mL of water, 100 mL of aqueous 1000 µg mL-1 S solution and water to 1 l) and 4 mL of BaCl2 solution After shaking for 15 min, the absorbance of the mixture as measured at 630 nm. Results compared well with those obtained using a continuous-flow analyzer. method.
Sulfate Ion exchange Sample preparation Extraction Membrane Method comparison

"A Rapid And Sensitive Flow Injection Technique For The Analysis Of Ammonium In Soil Extracts"
Commun. Soil Sci. Plant Anal. 1993 Volume 24, Issue 3-4 Pages 277-284
Alves, B.J.R.;Boddey, R.M.;Urquiaga, S.S.

Abstract: The steam distillation technique for the quantification of soil mineral nitrogen is not well adapted to estimate very low levels of NH-4+ and NO-3-such as those found in tropical pastures. In this paper we describe a flow injection analysis (FIA) technique for the direct estimation of soil ammonium in potassium chloride extracts. The technique is based on the salicylate/hypochlorite colorimetric reaction with the resulting coloration read at 647 nm. The speed of the reaction was increased by immersing the reaction coils in a water bath maintained at 70°C. The technique was capable of accurately quantifying ammonium to concentrations as low as 0.05 mg/NH4+-N/L (equivalent to 0.25 mg NH-4+-N/g dry soil) and sample throughputs of at least 60 samples per hour could be achieved. It was found that amino acids would also give a positive colorimetric reaction but that in the ten tropical soils examined this was not a significant source of error.
Ammonium Spectrophotometry Sample preparation

"Simplified Method For The Extraction And Analysis Of Available Nitrogen, Phosphorus, And Potassium In Soils"
Commun. Soil Sci. Plant Anal. 1994 Volume 25, Issue 13-14 Pages 2543-2560
Puchades, R.;Llopis, A.;Raigon, M.D.;Peris Tortajada, M.;Maquieira, A.

Abstract: Soil was dried and homogenized and nitrate, P and K extracted by two methods. For extraction with CaCl2 10 g of soil was shaken for 2 h with 100 mL of 10 mM CaCl2, the mixture was filtered and the filtrate collected for analysis. Extraction with 0.5 M NaHCO3 was by the Spanish Ministry of Agriculture, Fisheries and Food official method (1986) without using charcoal as a decolorizing agent. Nitrate in the extracts was determined by the FIA method of Raigon et al. (Analysis, 1992, 20, 483), P was determined by the reversed FIA system of Perez-Garcia et al., (Soil Sci., 1991, 151, 349) and K was determined by AES. Results obtained were compared with those achieved by the official methods. NaHCO3 was only suitable for the simultaneous extraction of nitrite P and K in alkaline soil and CaCl2 was only suitable for nitrate extraction.
Nitrate Phosphorus Potassium Sample preparation Spectrophotometry Reverse

"Spectrophotometric Determination Of Silicon In Soil Solutions By Flow Injection Analysis: Reduction Of Phosphate Interference"
Commun. Soil Sci. Plant Anal. 1994 Volume 25, Issue 19-20 Pages 3241-3256
Raben Lange, B.;Bendtsen, A.B.;Jorgensen, S.S.

Abstract: A flow injection analysis (FIA) procedure for the determination of dissolved silica (0.04-20 mgL Si) in aqueous solution has been optimized to reduce phosphate interference. Determinations are based on measurement of absorbance at 790 nm of heteropoly molybdenum blue formed by reduction with ascorbic acid at room temperature. Results obtained compared well with those obtained by a manual reference method and a proprietary FIA method except in solutions high in dissolved humic material where slightly higher values were obtained by the optimized method. In a standard addition mode the optimized method yielded 5-15% lower values than in the ordinary model. Soil solutions investigated were very low in phosphate but phosphate spiking experiments demonstrated that phosphate interference was less than in model solutions matched in metal ion concentrations.
Silicon Spectrophotometry Optimization Interferences

"Paper Test Strips For Rapid Determination Of Nitrate Tracer"
Commun. Soil Sci. Plant Anal. 1995 Volume 26, Issue 11-12 Pages 1885-1894
Holden, N.M.;Scholefield, D.

Abstract: A soil block (5.4 x 3.4 x 1.2 m) was isolated in situ by evacuating a trench (1.2 m depth) round it. The vertical faces of the block were rendered with clay and the sides were supported. The block was instrumented with tensiometers, time-domain - reflectometry waveguides, and suction-cup lysimeters. The lysimeters were connected to sample traps to form part of an in situ FIA system (details given). The analysis of soil water nitrate collected in the traps was carried out with a Merck RQflex reflectometer with 'Reflectoquant' nitrate test-strips. This technique permitted many samples (180/h) to be analyzed in near-real time and was highly suited to monitoring research where strong concentration tracers were used. It was not as accurate as a standard laboratory system but was useful for in situ analysis.
Nitrate Reflectometry Method comparison

"Flow Injection Systems With A Stream Splitting And A Dialysis Unit For The Soil Analysis Of Sodium And Potassium By Flame-emission Spectrometry, And Calcium And Magnesium By Atomic Absorption Spectrophotometry"
Commun. Soil Sci. Plant Anal. 1995 Volume 26, Issue 1-2 Pages 183-195
Ferreira, A.M.R.;Rangel, A.O.S.S.;Lima, J.L.F.C.

Abstract: Three FIA manifolds were developed to dilute samples, add reagents and introduce soil extracts into detection systems. Sample dilution to detector concentration range was achieved by incorporating a stream splitting and dialysis unit (equipment described). Sample injection was via a Rheodyne type 50 valve. To prepare soil for soluble ion determination, samples were air-dried, ground and sieved to 1 mm; 5 g were shaken with 25 mL water for 30 min. To extract ions, 5 g samples were shaken with 25 mL 1 M ammonium acetate pH 7 and filtered. Na and K were determined using a Jenway PFP7 flame photometer with air-butane flame. To detect Ca and Mg AAS was performed using a GBC 902 with air-acetylene flame. A stream splitting unit enabled determination of soluble Na and K between 0.3-100 ppm and 2.5-300 ppm, respectively. Available Na and soluble Ca and Mg were determined between 2-300 ppm, 3-200 ppm and 0.2-20 ppm, respectively. An additional dialysis unit allowed determination of available K, Ca and Mg between 0.5-1100 ppm, 57-2250 ppm and 15-400 ppm respectively. Results from the developed FIA systems compared well with a reference procedure. The method achieved 60-150 samples per h with RSD 4%.
Calcium Magnesium Potassium Sodium Spectrophotometry Spectrophotometry Sample preparation Dialysis Manifold comparison Method comparison Sample splitting

"A Simple And Inexpensive Method For Chromium Speciation In Soil Extracts"
Commun. Soil Sci. Plant Anal. 1995 Volume 26, Issue 13-14 Pages 2051-2065
Prokisch, J.;Kovacs, B.;Gyori, Z.;Loch, J.

Abstract: Chromium (Cr) appears in two stable forms in nature as Cr(III) and Cr(VI). Hexavalent chromium (CrO-4-2-; Cr-2O-7-2-) is very toxic and carcinogenic, while inorganic Cr(III), however, is essential for mammals. Only two methods, atomic absorption and inductively coupled plasma atomic emission (ICP) spectrometry, provide information on the total amount of Cr in a test solution. This is the reason that several efforts have been made with regard to Cr speciation. Either an acidic or a basic activated aluminum oxide and a reversed phase C-18 column or an ion exchanger column are used for the separation of chromium(III) from chromium(VI) in FIA and HPLC analyzes. In our experiments, acidic-activated aluminum oxide was used for separation. This alumina was placed into a silicon tube and connected to an ICP spectrometer between the nebulizer and peristaltic pump. The average grain size of the alumina was large enough that the solution could be pumped through the µcolumn. Acidic-activated aluminum oxide in the 2.0 to 8.0 pH range adsorbs the chromate anion but not the Cr(III) cation. During this stage, the Cr(III) content of a sample is measurable. The adsorbed chromate can be eluted with a strong acid. The height or area of the elution peak can be used for the calibration of Cr(VI). Detection limits of 4 µg/kg and 0.5 µg/kg were obtained for Cr(III) and Cr(VI), respectively. The effects of sulfate and phosphate anions on the surface of the alumina on chromate adsorption were also evaluated. This method was used for the measurement of Cr(VI) concentration by 0.01 M CaCl-2 extraction of soil.
Chromium(III) Chromium(VI) Spectrophotometry Sample preparation Speciation Interferences Alumina C18

"Bray And Kurtz Phosphorus (P1), 1M-potassium Chloride, And Saturated Calcium Oxide Extraction Of Soil Nitrate Comparison To 2M-potassium Chloride"
Commun. Soil Sci. Plant Anal. 1995 Volume 26, Issue 3-4 Pages 453-457
Vaughan, B.;Denning, J.;Frank, H.

Abstract: Soil nitrate was extracted in duplicate by shaking with:0.03 M NH4F in 0.025 M-HCl (1:10) for 5 min; 1 M KCl (1:10) for 60 min; 0.055 M CaO (1:3) for 15 min, and the routinely used 2 M KCl (1:10) for 60 min. The extracts were analyzed using the LACHAT Quickchem Method 12-107-04-C with the modifications described by Vaughan and Peplinski (Ibid., 1993, 24, 1003). The use of different extractants did not significantly affect the amount of soil nitrate extracted; all had similar reproducibilities with RSD 5% and a mean value of 14 ppm nitrate-N. Simultaneous extraction of nitrate with routinely used soil test extractants will save labour and laboratory expenses.
Nitrate Sample preparation Lachat

"Automated Method For Sulfate Determination In Soil-plant Extracts And Waters"
Commun. Soil Sci. Plant Anal. 1996 Volume 27, Issue 3-4 Pages 727-740
Coutinho, J.

Abstract: Soil was extracted with water and plants were wet digested with HNO3 and HClO4 by the method of Jones et al. ('Plant Analysis Handbook,' Micro-Macro Publishing, Athens, GA, USA, 1991). The extract or digest was sampled for 30 s and the resulting stream (0.16 ml/min) was merged with an air segmented stream (1.4 ml/min) of water containing 3 ml/l of Brij 35% and passed through a mixing coil. A reagent steam (0.23 ml/min) of BaCl2 containing gelatine merged with the sample stream, the resulting precipitate containing solution passed through a second mixing coil to a 50 mm flow-through cell where the absorbance of the precipitate turbidity was measured at 420 nm. The system was used to measure up to 100 mg/l of S; the system was adapted for the range up to 10 mg/l of S by increasing the sample time to 60 s, the water stream contained 20 ml/l of Brij 35% at 0.16 ml/min and the flow rate of the sample stream was 1.4 ml/min. Calibration graphs were linear for 20-100 mg/l of S and 0.10 mg/l of S by the respective systems with corresponding RSD (n = 10) of 0.7-6.9% and 1.3-6.1%.
Sulfate Sample preparation Turbidimetry

"Determination Of Chloride In Soils By Flow Injection Potentiometric Pseudotitration"
Commun. Soil Sci. Plant Anal. 1996 Volume 27, Issue 5-8 Pages 1437-1445
Ferreira, A.M.R.;Rangel, A.O.S.S.;Lima, J.L.F.C.

Abstract: Air-dried, ground and sieved soil was shaken with water for 30 min, the mixture was filtered under reduced pressure, and the filtrate was stirred with activated charcoal and refiltered. The filtrate was injected into a carrier stream (3 ml/min) of 50 µM-AgNO3/ 1 mM HNO3/0.2 M KNO3 that then passed through an earthed tubular electrode and into a 300 µL mixing chamber with provision for stirring. Pseudotitrations were performed with use of a double-junction reference electrode, with 0.2 M KNO3 in the outer compartment, and a tubular Ag+-selective electrode with a homogenous crystalline membrane as an indicator electrode as described by Ferreira et al. (Food Chem., 1994, 50, 211). The calibration graph was linear for 5-500 ppm of chloride in dried soil with RSD (n = 10) of 0.42-4.8%. Sampling rates were 60-160 per h. A single-channel flow injection analysis (FIA) system for the pseudo-titration of chloride in soils was developed using a tubular silver ion selective electrode with a homogeneous crystalline membrane of Ag2S as potentiometric detector. This system allows the determination of chloride in soil extracts from 1 to 100 ppm. The results obtained for 15 soil extracts are in good agreement with those provided by the classical procedures with sampling rates varying from 60 to 160 determinations per hour with good precision (relative standard deviations lower than 4.8%).
Chloride Sample preparation Potentiometry Electrode Electrode Method comparison Well stirred mixing chamber Titrations

"The Molybdate/ascorbic Acid Blue Method For The Phosphorus Determination In Very Dilute And Colored Extracts By Segmented-flow Analysis"
Commun. Soil Sci. Plant Anal. 1996 Volume 27, Issue 5-8 Pages 1363-1375
Coutinho, J.

Abstract: Soil was extracted by the method of Houba et al. (Ibid., 1990, 21, 2281) and the extract was injected into an FIA system for 100 s with air segmentation. The sample stream (1.6 ml/min) merged with a stream of 12 M HCl plus FFD6 wetting agent (0.1 ml/min), and the resulting stream passed through a five-turn mixing coil and then through a 20-turn mixing coil in a water bath at 50°C to a 70 cm dialyser for dialysis against an air-segmented stream of water containing 6 ml/l of FFD6 (0.8 ml/l). The dialysed stream then merged with streams of ammonium molybdate solution (0.1 ml/min) and ascorbic acid/antimony potassium tartrate solution (0.1 ml/min) and, after passage through a ten-turn mixing coil, the absorbance was measured at 880 nm. The calibration graph was linear for up to 400 µg/l of P with RSD (n = 10) of 0.6-5.6%. The detection limit was 2.8 µg/l of P. The method was also applied to waste water.
Phosphorus Spectrophotometry Dialysis

"Use Of Dialysis To Limit Interferences In The Turbidimetric Determination Of Sulfate"
Commun. Soil Sci. Plant Anal. 1996 Volume 27, Issue 9-10 Pages 2159-2169
Menzies, N.W.;Kameni, R.

Abstract: Soil (2 g) was shaken for 2 days with 20 mL 1.5 mM CaCl2/0.5 mM CaSO4, and subsequently centrifuged at 1000 g. The extracts were dialysed and analyzed by continuous-flow turbidimetry using BaCl2 reagent and detection at 420 nm (details given). The effects of particulates and organic matter on the determination of sulfate were assessed using filtration (0.025 µm) and H2O2 digestion (no details given). The dialysed solutions were additionally analyzed on a Waters IC Pac A anion-exchange column (dimensions not given) equipped with a 300 mg Alltech C18 guard column (dimensions not given), aqueous 1.5 mM sodium gluconate/5.8 mM boric acid/1.3 mM sodium borate/acetonitrile/glycerol as mobile phase (1.2 ml/min) and conductivity detection. Total S and organic C in the dialysed solutions were determined by ICP-AES at 182 and 193.1 nm respectively. Turbidimetric calibration graphs were linear from 0.1-2 mM sulfate, with quantitative recovery (no data presented). The turbidimetric results were comparable to those obtained by ion chromatography.
Sulfate Turbidimetry Spectrophotometry Sample preparation Dialysis Interferences

"Comparison Of Stirring And Vortex Mixing For The Extraction Of Available Nutrients From Soil Using A Laboratory Robot"
Commun. Soil Sci. Plant Anal. 1996 Volume 27, Issue 9-10 Pages 2213-2220
Bunnell, A.M.;Langan, P.A.;Quigley, M.N.;Reid, W.S.

Abstract: Soil was dried at 50°C and sieved through a 2 mm screen. Portions (10 ml) of the dried soil plus 1 mL of activated C were shaken with 50 mL of a solution comprising 5 kg sodium acetate trihydrate and 1.6 l anhydrous acetic acid in 50 l water of pH 4.8±0.5 (Morgan solution), and filtered. Further extractions were performed robotically using vortex or paddle stirring using 2 mL of dried soil and 10 mL of extraction solution, and similar soil:extractant ratios with 3-6 mL of soil. Using continuous-flow analysis, Al, Cu, Ca, K, Mg, Zn, Mn(II) and Fe(III) were determined by ICP-AES, and nitrate and phosphate by colorimetry (no details given). Robotic paddle stirring was shown to efficiently aid the extraction of the analytes, irrespective of the actual soil:extractant volumes used.
Aluminum Calcium Copper Iron(III) Magnesium Manganese(II) Zinc Spectrophotometry Sample preparation Robot

"An Automatic Procedure For Determination Of Available Iron In Indian Soils"
Commun. Soil Sci. Plant Anal. 1997 Volume 28, Issue 19-20 Pages 1859-1870
Chikhalikar, S.;Patel, K.S.

Abstract: An online automatic procedure for the flow injection analysis (FIA) determination of iron (Fe) in a variety of soil extracts with common laboratory reagents, i.e., thiocyanate, thiocyanate +1, 10-phenanthroline/bipyridine has been tested. The apparent molar absorptivity of the complexes lies in the range of (5.5-7.0) x 10(3) L mol-1 cm-1 at an absorption maximum between 470-495 nm. The detection limit of the method is 15 ppb Fe. The sample output is 100 samples/hr. Almost all ions associated with Fe in the soil extract do not interfere in this method. Optimization of FIA variables, composition of the complex, and effect of other ions on the determination of Fe are discussed. The method has been used for determination of Fe status in a variety of agricultural soils in east Madhya Pradesh, India. 9 References
Iron Spectrophotometry Sample preparation Optimization Interferences

"Statistical Evaluation Of Phosphorus Breakthrough Profiles Using A Segmented Exponential Model"
Commun. Soil Sci. Plant Anal. 1997 Volume 28, Issue 3-5 Pages 395-406
McGeehan, S.L.;Shafii, B.;Naylor, D.V.;Price, W.J.

Abstract: Few studies have utilized a statistical approach for the evaluation and comparison of breakthrough profiles obtained from soil column investigations. Our objective was to investigate the use of nonlinear estimation techniques to identify the phosphorus (P) breakthrough point and other parameters endemic to breakthrough data. Four soils exhibiting a range in physical and chemical properties were leached under saturated-flow conditions with a 10 mg P/Z solution for 34 days. Leachate P concentrations were analyzed by flow injection colorimetric analysis. A four-parameter segmented exponential model provided a good fit for the breakthrough data in each soil tested. In addition to identifying the breakthrough point, the model parameters provided estimates of other identifiable aspects of a breakthrough profile including background P concentration, equilibrium P concentration, and the rate of concentration change once breakthrough is attained. Estimation of these parameters also facilitated statistical comparison of breakthrough profiles from different soils. Single and joint hypothesis tests showed that significant differences existed among the breakthrough profiles, the breakthrough points, and the rates of concentration change. Additionally, simulation was used to examine the correlation structure between the estimated breakthrough point and 17 soil properties. The simulation showed that six soil properties-ammonium oxalate extractable aluminum (Al) and iron (Fe), citrate dithionite extractable Al, CaCl2, and acetate extractable P, and P sorption capacity-were strongly correlated with P breakthrough. 23 references.
Phosphorus Spectrophotometry Column Modeling Optimization

"Determination Of Iron In Soils By Flow Injection Atomic Absorption Spectrometry"
Commun. Soil Sci. Plant Anal. 1998 Volume 29, Issue 15-16 Pages 2407-2414
Ferreira, A.M.R.;Rangel, A.O.S.S.;Lima, J.L.F.C.

Abstract: A single-channel flow injection system was optimized for the determination of available iron (Fe) in soil extracts by atomic absorption spectrophotometry. This method of introducing the samples in the spectrophotometer worked particularly well in preventing blockage of the burner head which was observed in the conventional introduction of Fe for its determination by atomic absorption spectrophotometry. The appropriate selection of the manifold parameters, such as injection volume, tube length and flow rate, allowed introduction of any soil ext. without requiring any pre-treatment. This system allowed determinations at a detection limit of 0.36 mg L-1 to 5 mg L-1, with an output of 300 determinations per h. The results obtained for anal. of 15 soil extracts were in good agreement with those provided by the colorimetric method, with average relative deviations of 1.6%. Relative standard deviations of 4.8, 2.5, and 2.3% were obtained for contents of 1.03, 1.85, and 3.99 mg Fe L-1, respectively.
Iron Sample preparation Spectrophotometry Optimization Method comparison

"Flow Injection Systems For Elemental Soil Analysis Determinations"
Commun. Soil Sci. Plant Anal. 1998 Volume 29, Issue 3-4 Pages 327-360
Ferreira, A.M.R.;Rangel, A.O.S.S.;Lima, J.L.F.C.

Abstract: A review with ~80 references. Flow injection analysis (FIA) is becoming an important automated procedure for the elemental anal. of agricultural and environmental samples. This paper reviews the application of the FIA technique for soil elemental anal. determinations, giving short descriptions of the required flow manifolds by highlighting some of their most important features. Flow injection analysis (FIA) is becoming an important automated procedure for the elemental analysis of agricultural and environmental samples. This paper reviews the application of the FIA technique for soil elemental analysis determinations, giving short descriptions of the required flow manifolds by highlighting some of their most important features.
Nitrate Nitrite Ammonium Phosphorus Spectrophotometry Automation Review Merging zones

"Online Monitoring Of Aromatic Hydrocarbons Using A Near-ultraviolet Fibre-optic Absorption Sensor"
Environ. Sci. Technol. 1995 Volume 29, Issue 6 Pages 1576-1580
Tye E. Barber, Walter G. Fisher, and Eric A. Wachter

Abstract: flow through sensor is described for the determination of aromatic hydrocarbons based on the measurement of the absorption of vapor components. The sensor comprised an absorption cell with light transmitted through the cell by a fused-silica optical fiber to a photodiode detector (schematic given). The sample was scanned at 230-300 nm in 0.1 nm steps acquiring data for 0.2 s at each wavelength. The sensor was able to detect benzene and its derivatives and was used continually for 5 weeks at an underground stripping site to remove petrochemicals from soil.
Hydrocarbons, aromatic Benzene Sensor Spectrophotometry Optical fiber

"Development Of Tyrosinase Based Biosensor And Its Application For Monitoring Of Bioremediation Of Phenol And Phenolic Compounds"
Environ. Sci. Technol. 1998 Volume 32, Issue 6 Pages 828-832
Juraj Svitel and Stanislav Miertus

Abstract: A tyrosinase-modified solid composite biosensor has been developed, and its application for the determination of phenol and related compounds in environmental samples was studied. The composite transducer for amperometric biosensor was based on graphite powder modified with tyrosinase and 2-hexadecanol used as a solid binding matrix. The response of a biosensor modified with 4% of tyrosinase was linear up to 2.5 µM, the sensitivity was 0.0225 µA µM, and the detection limit 0.2 µM. Various parameters influencing biosensor performance have been also studied: working potential, buffer concentration, pH, and response with other compounds. The sensitivity of biosensor without surface renewal decreased to 20% of the initial value after 1 month. The sensitivity is restored after surface renewing. The biosensor was tested in laboratory-scale experiments for monitoring of phenol bioremediation in water and soil. The biosensor was also tested for analysis of other phenolic wastes: leachate from leather processing containing chlorophenols and waste from oil processing containing polyphenols.
Phenol Phenols Sensor Amperometry Apparatus Detector Optimization

"Flow Injection Hydride-generation Atomic Absorption Spectrometry (FI-HG-AAS) And Spectrophotometric Methods For Determination Of Lead In Environmental Samples"
Environ. Technol. 1996 Volume 17, Issue 12 Pages 1327-1337
Samanta G.; Chakraborti D.

Abstract: Soil or dust (0.25-0.5 g) was digested with 2 mL HNO3 and 0.5 mL 30% H2O2 at 120°C in a PTFE bomb (details given). The digest was evaporated, the residue was dissolved in ~0.1N-HNO3 and the solution was filtered. A portion (50 µL) was injected into a stream (1 ml/min) of 6% HNO3 containing 9% ammonium persulfate which merged with a stream (1 ml/min) of 1% NaOH containing 8% NaBH4 for hydride generation, followed by AAS (details given). Alternatively, a portion of digest containing methyl orange indicator was adjusted to ~pH 3.6 with 0.1N-KOH, mixed with phthalate buffer of pH 3.6, and shaken with 10 mL portions of dithizone in CHCl3 until the organic phase became green. The aqueous phase was washed with CHCl3, then mixed with hydroxylammonium chloride and HCl. Pb was extracted by shaking the solution with dibenzyldithiocarbamate, the extract was evaporated, the residue heated with HClO4 and then boiled with water. The solution was mixed with ammonia buffer of pH 10 and 0.05% 4-(2-pyridylazo)resorcinol monosodium salt solution prior to absorbance measurement at 530 nm. The detection limits for the two methods were 2 µg/l Pb and 0.5 mg/l Pb, respectively. The results were compared with those obtained by ICP-AES and flame AAS.
Lead Spectrophotometry Method comparison Dithizone

"Determination Of Soil Available Phosphorus By Flow Injection Analysis"
Fenxi Huaxue 1981 Volume 9, Issue 5 Pages 586-588
Sun, L.;Gao, Z.;Li, L.;Yu, X.;Fang, Z.L.

Abstract: Soil-available P was determined by the methods of J. Ruzicha et al. (1978) and of Zhaolun Fang (1981) (flow-injection anal.). A soil sample was extd. with 20 volumes of 0.5 M NaHCO3, and 10 mL of the ext. was treated with 2.5 mL of 2N H2SO4 and allowed to stand for 30 min. The ext. was analyzed by CLA-1600 type autoanalyzer (Carlo Erba Co.). An aliquot was injected into the analyzed at m.6 mL/min accompanied by injection of a solution containing NH4 molybdate, tartaric acid, concentrated H2SO4, and water at 6.7 mL/min, and a solution containing SnCl2, concentrated HCl, and water at 1.72 mL/min for color reactions. Results compared well with those determined by the conventional (manual) method. The relative standard deviation was 1.8% when 0.46 mg P2O5/100 g soil was analyzed but was 0.4% when a standard solution containing 0.8 ppm P2O5 was analyzed.
Phosphorus Spectrophotometry Method comparison

"Simultaneous Spectrophotometric Determination Of Nitrate And Nitrite In Water And Soil Extracts By Flow Injection Analysis"
Fenxi Huaxue 1983 Volume 11, Issue 2 Pages 93-97
Xu Shukun, Fang Zhaolun

Abstract: A new method for the simultaneous spectrophotometric determination of nitrate and nitrite in water and soil extracts by flow injection analysis with non-carcinogenic compound,α-naphthylamine-7-sulphonic acid and sulfanilamide as developing agent was proposed. An on-line cadmium-coated zinc reductor column was used to reduce nitrate to nitrite. Potassium sodium tartrate was found to promote the reaction rate. This was especially advantageous when applied to the flow injection analysis.The detection limits were 10 µg/1 for NO3--N and 1 µg/l for NO2--N.The precision was 0.7% for NO3--N at a level of 2 mg/l and 1% for NO2--N at 1 mg/l. The sampling rate was 60 samples per hr, i.e.120 determinations per hr. The optimization of reaction coil length,sample volume, potassium sodium tartrate concentration and reductor length were discussed.
Nitrate Nitrite Sample preparation Spectrophotometry Simultaneous analysis Speciation Differential detection

"Flow Injection Analysis Of Iron In Soil Extracts"
Fenxi Huaxue 1984 Volume 12, Issue 8 Pages 759-761
Cui Hongbo, Fang Zhaolun

Abstract: Air-dried soil (5 g) is stirred for 30 min with 25 mL of 0.1 M HCl, the solution is filtered, and 5 mL of the filtrate (after decolorization, if necessary, by heating with 1 to 3 drops of aqueous H2O2) is diluted to 50 mL with water. Soluble Fe is determined spectrophotometrically as the complex of Fe(II) with 2,2'-bipyridyl(I) in a flow injection system by injection of 30 µL of the test solution into a de-aerated reagent carrier stream of pH 4, 0.01 M in K H phthalate, containing 0.05% of I and 0.2 % of ascorbic acid, which is pumped at 2 mL min-1 along the polyethylene reaction tube (1 m x 0.5 mm) to the cell for absorbance measurement at 540 nm. The range of determination is 0.02 to 7 ppm of Fe in the injected solution and up to 200 samples can be analyzed per h.
Iron Spectrophotometry

"Automatic Flow Injection Colorimetric Determination Of Available Aluminum In Soils"
Fenxi Huaxue 1984 Volume 12, Issue 8 Pages 754-756
Cui Hongbo, Meng Lihong, Zhu Zhaohai

Abstract: The air-dried soil sample (0.5 g) is heated for 5 min on a boiling-water bath with 100 mL of 0.5 M NaOH, the cooled mixture is filtered and 1 to 10 mL of the filtrate is neutralized with 0.5 M HCl and diluted with water to 25 mL. The Al in solution is determined spectrophotometrically by injection of 80 µL of the test solution into a de-aerated aqueous carrier stream containing 0.01% of aluminon and 0.01 M in K H phthalate that is pumped at 3.5 mL min-1 along the reaction tube (1 m x 0.5 mm) to the cell for absorbance measurement at 540 nm. The calibration range for Al in the test solution is from 0.05 to 4 ppm; with 1.5 ppm of Al the coefficient of variation is 0.5%, and recoveries are between 98 and 102%.
Aluminum Sample preparation Spectrophotometry Automation

"Determination Of Total Nitrogen In Soils With An Ammonia Gas-sensitive Electrode By The Flow Injection Merging Zones Technique"
Fenxi Huaxue 1984 Volume 12, Issue 12 Pages 1096-1098
Gao, Zhan;Chen, Jin

Abstract: An air-dried soil sample (0.5 g) was moistened and then digested with concentrated H2SO4 (6 ml), with K2SO4 - CuSO4 (20:1) as catalyst (1 g), in an i.r. oven (300°C to 400°C) for 2 to 2.5 h. For the flow injection analysis the system was fitted with a dual-channel sampling gate to produce a merging zone of the digested sample and 5 M NaOH. Interference from common ions was insignificant. The results compared favourably with those by the indophenol blue colorimetric method. Recoveries ranged from 88 to 110%.
Nitrogen, total Electrode Sample preparation Interferences Merging zones Method comparison

"Flow Injection Analysis For Soil Available Zinc By Solvent Extraction With Dithizone"
Fenxi Huaxue 1985 Volume 13, Issue 6 Pages 447-449
Sun, L.;Li, L.;Fang, Z.L.

Abstract: A powdered sample (25 g) is shaken in 50 mL of a mixture of 5 mM diethylenetriaminepenta-acetic acid and 0.01 M CaCl2 - 0.1 M triethanolamine for 2 h, and the mixture is filtered. The filtrate is extracted with a 0.002% solution of dithizone in CCl4 in a flow injection analyzer., and the absorbance of the organic phase is measured at 535 nm. The calibration graph is rectilinear up to 5 ppm. The recoveries of 1 ppm of Zn added to soil range from 99 to 104%, and the coefficient of variation is 1.4%. The detection limit is 0.015 ppm. The results are in good agreement with those obtained by AAS and ICP-AES.
Zinc Spectrophotometry Sample preparation Organic phase detection Dithizone Solvent extraction

"Preparation Of PVC Tubular Flow-through Potassium Ion Selective Electrode And Its Application In Flow Injection Analysis"
Fenxi Huaxue 1988 Volume 16, Issue 4 Pages 320-323
Cui, H.;Zhang, S.

Abstract: The electrode is prepared from 1% of valinomycin, 65.6% of a di-(iso-octyl) fatty acid ester, 0.6% of K tetra-(4-chlorophenyl)borate and 32.6% of PVC powder, and is used in a flow injection analysis system (diagrams of the electrode and system given). For analysis of soil, a 5-g air-dried sample is extracted with 0.1 M HCl for 30 min; after 2 h, 25 mL of the supernatant solution is treated with 12 drops of triethanolamine (pH 8 to 9) and 0.1 M HCl - triethanolamine (1:5; pH 8.5) to 50 mL. The K+ content of a 350 µL portion of this solution is determined by injection into the flow stream (2.3 mL min-1) of 0.1 M HCl - triethanolamine (1:5; pH 8.5) containing 0.1 µg mL-1 of K+ as carrier. The detection limit is 0.05 ppm of K+. Up to 100 samples h-1 can be analyzed. Results agree well with those obtained by flame photometry.
Potassium Electrode Electrode Electrode Method comparison

"Semi-automated Flow Injection Analysis System For The Determination Of Trace Arsenic By Hydride Generation Atomic Absorption Spectrometry"
Fenxi Huaxue 1988 Volume 16, Issue 10 Pages 912-915
Wang, X.;Fang, Z.L.

Abstract: A flow injection analysis system with automated sample introduction was used to determine trace As in soil and plants by hydride-generation AAS. The sampling frequency was 220 h-1 for a sample volume of 0.4 mL. The detection limit was 0.1 µg L-1 and the coefficient of variation was 1.5% (n = 13) for 6 µg L-1 of As. Interference from foreign ions was less than for the manual method although serious interference from Fe(III) was observed; this was overcome by treating the sample with KI initially. Selenium also interfered at >20 µg l-1, but was masked by 10 mg L-1 of Cu in the acidic carrier solution.
Arsenic Spectrophotometry Interferences

"Determination Of Arsenic, Antimony And Bismuth By Flow Injection Analysis Hydride-generation Graphite-furnace Atomic Absorption Spectrometry"
Fenxi Huaxue 1992 Volume 20, Issue 6 Pages 670-673
Wang, Z.;Wang, Y.

Abstract: A method was developed for the determination of As, Sb and Bi by the cited technique and applied to the analysis of soil. Sample solution (prep. described) was injected into a carrier stream (5.6 to 6.4 mL min-1) of 1 M HCl - 1 M HNO3 - 2 M H2SO4 which merged with a stream of NaBH4 in 0.2% NaOH. The mixture was passed to a gas - liquid separator where the generated hydrides were carried to the graphite-furnace by a stream of Ar (250 mL min-1) for AAS determination of As, Sb and Bi with measurement at 193.7, 217.6 and 223 nm, respectively. Recoveries were 94 to 99% with coefficient of variation of 0.4 to 0.9%. Detection limits for As, Sb and Bi were 6.29, 9.21 and 3.77 pg, respectively. The combined method of flow injection analysis with hydride generation and graphite furnace-at. absorption spectrometry (GFAAS) is studied. This method has high sensitivity, low detection limit, high precision, and high selectivity. As, Sb and Bi were determined., the detection limit was all below 10 pg. The interference mechanism of Cu has also been studied with x-ray diffraction method.
Arsenic Antimony Bismuth Spectrophotometry Phase separator Interferences Volatile generation Volatile generation

"Determination Of Arsenic By Flow Injection Analysis With Hydride-generation Spectrophotometry"
Fenxi Huaxue 1992 Volume 20, Issue 7 Pages 810-812
Liu, G.Q.;Wang, C.X.;Xie, B.;Wu, W.H.

Abstract: A flow injection online hydride generation spectrophotometric system is described for the cited determination (schematic given). The absorption solution used was HNO3 - AgNO3 - PVC - ethanol; there was no need for any carrier solution The system was applied to the analysis of soil. Sample (0.2 g) was wetted with water, treated with 10 mL of concentrated HNO3 and heated to fumeless. The cooled residual solution (~1 ml) was mixed with 10 mL of 0.5 M HCl and a little ascorbic acid, the mixture was heated for 2 to 3 min and cooled to room temperature The solution was diluted with HCl - KCl buffer solution (pH 1.1) and analyzed by the proposed system. Sample throughput was 30 h-1.
Arsenic Sample preparation Spectrophotometry Buffer Volatile generation Volatile generation

"Preparation And Application Of Integrated Microconduit Ion-selective Electrodes"
Fenxi Huaxue 1992 Volume 20, Issue 7 Pages 790-793
Cui, H.B.;Sun, J.Y.;Jiang, Z.Y.;Cong, F.

Abstract: A novel integrated microconduit ion-selective electrode functional piece was designed and its electrochemical characteristics are discussed. The electrode was applied in the determination by flow injection analysis of K+, Na+, Cl-, F-, I-, atropine and scopolamine in soil, water, serum and pharmaceuticals and in the determination of pH. The results obtained compared well with those of standard methods.
Potassium(I) Sodium(I) Chloride Fluoride Iodide Atropine Scopolamine pH Electrode Microfluidic Method comparison Standard method

"Application Of Flow Injection Hydride-generation Graphite-furnace Atomic Absorption Spectrometry. 2. Determination Of Trace Germanium"
Fenxi Huaxue 1994 Volume 22, Issue 6 Pages 586-589
Ma, Y.P.;Han, Y.Q.;Ariguli, R.

Abstract: Sample (0.1-0.5 g) was digested with HNO3 or HNO3, HClO4 and HF, and then diluted with water to 25 mL. Using a self-developed flow injection hydride-generation graphite-furnace AAS system, the solution (500 µL) was introduced and carried by a stream of water at 3.2 ml/min to react with 20% Na3PO4 at 5 ml/min in a reaction tube (40 cm long) then with 0.3 M H3PO4 at 3.2 ml/min in a reactor (120 cm long) before reacting with 0.5% KBH4 at 3.2 ml/min. The generated hydride was transferred with Ar as carrier gas at 14 ml/min to an automatic sampler (coated by treating with PdCl2 and KBH4) then to the AAS instrument equipped with a pyrolytically-coated graphite tube. Drying, pre-concentration and atomization temperature were 120°C, 750°C for 35 s and 2200°C, respectively. Detection limit was 1.3 pg. Recovery was 99.5-10%. Little interference was observed. Results were compared with those of the GF and hydride-generation flame methods. Sampling frequency was 30 runs per h. The method was utilized for assay of soil and Chinese herbal drugs including Rhodiola kirilouic and Lycium chinense.
Germanium Spectrophotometry Sample preparation Interferences Method comparison Volatile generation Preconcentration Volatile generation

"Silver-diethyldithiocarbamate System For The Determination Of Arsenic By Flow Injection Analysis"
Fenxi Huaxue 1996 Volume 24, Issue 12 Pages 1429-1432
Liu, G.Q.;Wang, C.X.;Cao, F.X.

Abstract: Sample was introduced in the flow injection analysis system (diagram shown) to react with 1% KBH4 solution and the generated AsH3 was transferred by N2 carrier gas at 30 ml/min to an absorption cell containing silver diethyldithiocarbamate/triethanolamine solution in CHCl3, during which the gas flow was stopped for 4 min (i.e., 1 min after sampling). Having switched to the continuous spectrophotometric mode, the absorption was stopped and the absorption solution was allowed to flow-through the detection cell for measurement of the absorbance at 530 nm. The calibration graph was linear. When determining 0.3 µg/ml of As, the RSD (n = 11) was 4.8%. The method was used in the analysis of soil, with RSD of 3.1-6.2%. The sampling frequency was 15 per h.
Arsenic Spectrophotometry

"Determination Of Trace Arsenic By Flow Injection Hydride-generation Atomic Absorption Spectrometry With Online Reduction"
Fenxi Shiyanshi 1994 Volume 13, Issue 2 Pages 20-22
Xu, S.K.;Fang, Z.L.

Abstract: Water was mixed with concentrated HCl (2:1), injected and transferred at 4.4 ml/min to mix with a stream of KI in 1 M HCl (300 g/l) at 4.4 ml/min in a knotted reactor (1 m long, 0.5 cm i.d.). The sample was stored in a 400 µL sampling loop for 40 s and reduced by injection into a stream of NaBH4 in 0.125 M NaCH at 5 ml/min in the presence of a carrier stream of 1 M HCl at 8 ml/min in a mixer and then a reaction tube (both 20 cm/mg, 0.7 mm i.d.). The generated hydride was separated in a gas-liquid separator and transferred with Ar at 120 ml/min for AAS analysis. The detection limit was 0.1 µg/l of As. For 10 µg/l of As, recoveries ranged from 104-105% with RSD of 1.4-1.5%. Soil was similarly analyzed. The sampling rate was 55 samples/h.
Arsenic Spectrophotometry Knotted reactor Volatile generation Phase separator Redox Volatile generation

"Determination Of Aluminum In Water And Soils"
FIAstar Newsletter 1985 Volume 2, Issue 1 Pages 2-NA
Moller, J.

Abstract: NA
Aluminum Spectrophotometry Tecator

"Sequential Injection Method With Online Soil Extraction For Determination Of Chromium(VI)"
Field Anal. Chem. Technol. 1996 Volume 1, Issue 1 Pages 39-48
Jay W. Grate *, Richard H. Taylor

Abstract: Cr(VI) was determined in acidic, alkaline or water extracts of soil (preparation described) by colorimetric reaction with 1,5-diphenylcarbazide (DPC) using a sequential injection analysis system (diagram given). A piston pump with a 5 mL syringe and water as carrier solution were used to sequentially aspirate 48 µL 10% H2SO4, 25 µL sample solution and 44 µL 0.02 M DPC in aqueous 50% acetone into a holding column at 3 ml/min and then expel them through the detector cell by reversing the pump direction. The absorbance was measured at 540 nm. The calibration graph was linear for up to 5.5 mg/l Cr(VI), the detection limit was 20 µg/l and the sampling frequency was 70/h. For the determination of Cr(VI) in soil incorporating online extraction, 2O was pumped through the sample eight times at The extract (25 µL) was then analyzed as described above. Total Cr was determined by heating samples with equal volumes of 7.5 mM cerium(IV) sulfate in 75 mM H2SO4 for 2 min at 40°C prior to analysis.
Chromium Spectrophotometry Sample preparation Sequential injection Extraction

"Determination Of Copper, Zinc, Iron, Manganese, Sodium, Potassium, Calcium, And Magnesium In Plants And Soil By Flow Injection Atomic Absorption Spectrometry"
Guangpuxue Yu Guangpu Fenxi 1984 Volume 4, Issue 3 Pages 42-47
Zhang Sucun, Sun Lijing, Jiang Hengchun, Fang Zhaolun

Abstract: A FIA Method for the determination of Cu, Zn, Fe, Mn, Na, K, Ca and Mg by AAS was described. When determination of Cu, Zn, Fe, Mn, Na, and K, the water carrier stream was aspirated by nebulizer of AAS. The mono-channel manual rotary valve was used for sampling. The relative standard deviation was 1% at the sampling rate of 514 samples/hr. The merging zone technique was adapted for determination of Ca and Mg. The sample and lanthanum reagent were injected simultaneously into water carrier stream using dual channel manual rotary valve and peristatic pump, After the merging the stream was directed to burner. Consumption of lanthanum reagent was about 1% of that of manual method (0.4 mg/sample). The results obtained agreed well with those obtained by conventional AAS.
Copper Zinc Iron Manganese Sodium Potassium Calcium Magnesium Spectrophotometry Method comparison

"Cold Vapor Atomic Absorption Determination Of Mercury In Soil And Plants Using A Flow Injection Gas Diffusion System"
Guangpuxue Yu Guangpu Fenxi 1987 Volume 7, Issue 1 Pages 57-61
Zhang, S.;Fang, Z.L.;Sun, J.

Abstract: Samples of soil and plants were analyzed for Hg by using the method of De Andrade et al. (Anal. Abstr., 1984, 46, 4B69) with modifications to improve the detection limit and sampling frequency, and to increase the lifetime of the PTFE membrane. The method involved permeation of Hg vapor through a PTFE membrane, which separated the flow cell from the optical path of the Nippon Jarrell Ash spectrometer. Absorption was measured at 253.7 nm. The detection limit was 0.06 µg L-1 of Hg, the sampling frequency was 200 h-1 and the coefficient of variation was 1% (n = 22) for 4 µg L-1 of Hg.
Mercury Spectrophotometry Gas diffusion Teflon membrane

"Evaluation Of Three FIA Standard-addition Calibration Methods For ICP Spectroscopy"
Guangpuxue Yu Guangpu Fenxi 1990 Volume 10, Issue 2 Pages 49-53
Fan, S.;Fang, Z.L.

Abstract: Soil (0.2 to 0.5 g) is mixed with a few drops of water, 5 mL of HNO3 - HClO4 (3:1) and 3 mL of HF and then evaporated at 180°C to ~1 ml; 5 mL of 10% HCl is added to the residue which is then boiled. After cooling, the mixture is diluted with 10% HCl to 50 mL. Three methods used for analysis of the solution are those of Araujo (Anal. Chim. Acta, 1985, 17, 337), Tyson (Anal. Chim. Acta, 1983, 145, 159) and Fang (Anal. Chem., 1985, 57, 1457); procedures and diagrams of FIA systems are presented. Precision and recovery of these methods are compared, and their capabilities to compensating various matrix effects are detailed.
Sample preparation Spectrophotometry Standard additions calibration Dilution Manifold comparison

"Determination Of Trace Lanthanum In Natural Waters By A Flow Injection Online Preconcentration ICP System"
Guangpuxue Yu Guangpu Fenxi 1992 Volume 12, Issue 5 Pages 63-66
Fan, S.H.;Fang, Z.L.

Abstract: Sample (3.3 ml) at pH ~7 was applied at 5.5 mL min-1 into a flow injection system for pre-concentration. on a CL-P507 resin column (3 x 0.5 cm) for 35 s then eluted at 1 mL min-1 with 1 M HCl for 20 s; the eluate was mixed in a tube (35 cm x 0.35 mm) before analysis by ICP-AES with measurement at 379.5 nm. Recovery was 90 to 110% with a coefficient of variation of 1.7%. The detection limit was 0.7 µg L-1 of La. A 25- to 30-fold pre-concentration. could be achieved. Sampling frequency was 60 h-1. The method was employed for assay of tap water, polluted water and soil extract.
Lanthanum Spectrophotometry Sample preparation Preconcentration Resin

"Determination Of Trace Mercury In Environmental And Biological Samples By Flow Injection Hydride-generation Graphite-furnace AAS"
Guangpuxue Yu Guangpu Fenxi 1993 Volume 13, Issue 5 Pages 107-110
Ma, Y.P.;Gulikezi;Fang, X.H.

Abstract: Pre-treated sample (500 µL) was injected and carried by a stream of water (6 ml/min) to react with streams of 5 M HCl and 0.3% KBH4 (both at 1 ml/min). After passing through a gas-liquid separator, the generated Hg was carried by Ar at 50-80 ml/min to a self-made Au-coated graphite-furnace for AAS, with pre-concentration and atomization temperature of 45-160°C and 500°C and 600°C, respectively. By standard-additions method, recovery was 98-101%; RSD were 5-10%. The calibration graph was linear with a detection limit of 20 pg of Hg. The method was applied to assay of human hair, urine, soil and peach leaf. No interference was observed from co-existing ions. Sampling rate was 50 runs per h.
Mercury Spectrophotometry Interferences Preconcentration Standard additions calibration

"Determination Of Trace Molybdenum By Online Ion-exchange Preconcentration With A Flow Injection Inductively Coupled Plasma Atomic-emission Spectrophotometric System"
Guangpuxue Yu Guangpu Fenxi 1993 Volume 13, Issue 5 Pages 73-76
Guo, L.;Zhang, G.L.;Fang, Z.L.

Abstract: Tap water was injected at 5.7 ml/min into a micro-ion-exchange column (3 cm x 3 mm i.d.) packed with Dowex 1 resin (chloride form; 100 mesh) for dual-column online ion-exchange pre-concentration in a FIA system (diagram given) with 1.9 M ammonium chloride/0.4 M ammonium citrate as the eluent at 0.5 ml/min and 60°C over 5 min. The eluate was raised at 0.5 ml/min to the spectrophotometer with Ar as carrier gas (0.68 l/min) for ICP-AES of Mo with measurement at 281.62 nm. The observation height was set at 12 mm and plasma power was at 1.2 kW. Recoveries were 90-110% for 0.2 ng/l of Mo and RSD were 5.3%. An enrichment factor of 50 was achieved at sampling frequency of 12 samples per h. The method was applied to soil after treatment with 0.1 M oxalic acid and 0.175 M ammonium oxalate.
Molybdenum Ion exchange Spectrophotometry Preconcentration

"Determination Of Cyanide In Soil And Water By Flow Injection Analysis"
Huanjing Huaxue 1984 Volume 3, Issue 1 Pages 48-52
Cui, Hungbo; Zhu, Zhaohai; Fang, Zhaolun

Abstract: Cyanide in waters and soils is determined by flow-injection analysis using ion-selective electrode method with a AgI-Ag2S membrane electrode. The linear detection range and recoveries are 0.2-10 ppm and 98-102%, respectively; the relative standard deviation is 1.2% at the 1 ppm level. The optimal injection frequency for a sample at 0.2 mg/L was 120 samples/h.
Cyanide Electrode Electrode Optimization

"Comparison Of Active Aluminum Species In Coniferous Forest Soils Of Different Districts"
Huanjing Huaxue 1992 Volume 11, Issue 3 Pages 48-54
Ma Huichang, Feng Jianzhang, Wu Hua, Pang Shuwei

Abstract: Active Al species were leached from the cited soils with four different extractants before determination by flow injection analysis. The acidity of the soil had a significant effect on the amount of Al leached; the effect of chemical species on the determination was also evaluated.
Aluminum, labile Sample preparation pH

"Flow Injection Analysis By Ion-selective Electrodes, A Detachable Solid Membrane Chloride Ion-selective Electrode Used In The Determination Of Chloride In Soil Water Extracts"
Huanjing Kexue 1981 Volume 2, Issue 5 Pages 376-380
Gao Zhan; Lu Mingyuan

Abstract: The flow injection mol. determine the Cl- contents at 10^-3 - 10^-1 M in leachates with volume >10 mL with relative standard deviations 1-2%. The response potentials 50-150 mV are linearly related to Cl- concentrations <10-3 - 1 x 10^-1 M. For leachate samples containing Cl-, the method yields Cl- contents 0.12 and 0.98% compared to 0.14 and 0.92% determined by a volumetric method.
Chloride Electrode Method comparison

"Effect Of Dissolved Humic Compounds On The Determination Of Aqueous Aluminum By Three Spectrophotometric Methods"
Int. J. Environ. Anal. Chem. 1986 Volume 27, Issue 4 Pages 305-314
Royset, O.;Sullivan, T.J.

Abstract: The interference of humic and fulvic acids on the determination of Al in aqueous solution (e.g., from soil samples) was investigated. The methods involved(I): a quinolin-8-ol - isobutyl methyl ketone extraction with determination by the method of Barnes (Chem. Geol., 1975, 15, 177);(II) use of flow injection analysis applied to the frequently used catechol violet method; and (iii) use of flow injection analysis and Al - Eriochrome cyanine R (C. I. Mordant Blue 3) complex formation in presence of hexadecyltrimethylammonium for spectrophotometry. All methods were subject to interference from >10 mg L-1 of humic and fulvic acids in the determination of total monomeric Al. In the determination of acid-reactive Al, however, method(I) was not subject to interference from <200 mg L-1 of humic and fulvic acids, while interference was observed in methods(II) and (iii) from >20 mg L-1. Interference was pH-dependent and was minimized at higher pH values.
Aluminum Spectrophotometry Sample preparation Interferences 8-Hydroxyquinoline Extraction MIBK

"Speciation Of Heavy Metals In Polluted Soils By Sequential Extraction And ICP Spectrometry"
Int. J. Environ. Anal. Chem. 1987 Volume 29, Issue 4 Pages 305-315
Scokart, P.O.;Meeus Verdinne, K.;De Borger, R.

Abstract: An extraction column, into which a 1-g soil sample was packed, was connected directly to a sequential dual-channel ICP spectrometer, and was supplied (0.75 mL min -1) with water, 0.1 M BaCl2, 0.1 M acetate buffer - 0.05 M EDTA and 10% HNO3 in succession by a peristaltic pump. Cadmium and Zn were determined at 214.44 and 213.86 nm, respectively, in one channel and Cu and Pb at 224.7 and 220.35 nm, respectively, in the other. ''Chromatograms'' of the chemical species of these elements released by the successive eluents were thereby obtained. The results assisted in the optimization of the extraction of a particular metal species. The sums of the species of each of the four metals (residual fraction analyzed after digestion with HNO3 - HCl) agreed fairly well with the respective total values in two soils.
Metals, heavy Spectrophotometry Sample preparation Extraction Speciation

"Online HPLC Micro Extraction Of Zinc(II) And Cadmium(II) In Soil Slurries: A Chemical Speciation Method"
Int. J. Environ. Anal. Chem. 1996 Volume 64, Issue 3 Pages 217-231
Lam, M.T.;Gamble, D.S.;Chakrabarti, C.L.;Ismaily, A.L.

Abstract: A FIA system consisting of an online microfiltration unit coupled to an HPLC system is described for distinguishing between the labile surface binding and the intra-particle diffusion of metal ions in soils. Soil (0.08 g) was slurried in 40 mL water or mobile phase. At intervals of up to 72 h, 20 µL of the slurry was injected into the FIA system to determine the total metal-ion concentration. The injected soil particles were trapped in the online microfiltration unit (2 and 0.5 µm stainless steel frits in series) and extracted with the mobile phase (1 ml/min, 0.94 g sodium octane sulfonate/15 g tartaric acid/100 mL methanol made up to 2 l with water, of pH 3.5). Chromatography was performed on a Supelcosil LC-18 reversed-phase column (7.5 cm x 4.6 mm i.d.) with post-column reaction with 0.5 g/l 4-(2-pyridylazo)resorcinol (0.5 ml/min) and detection at 520 nm. At the same time intervals, portions of the slurry were filtered with an off-line filter and the filtrate was analyzed using the FIA system to determine the metal ions in solution. The methodology was applied to study the binding of Zn(II) and Cd(II) to soils collected from agricultural land.
Cadmium(2+) Zinc(II) HPLC Sample preparation Speciation Extraction

"Immunochemical Techniques And Immunosensors For The Analysis Of Dealkylated Degradation Products Of Atrazine"
Int. J. Environ. Anal. Chem. 1996 Volume 65, Issue 1-4 Pages 113-126
Wittmann, C.

Abstract: Field format dipstick and automated flow injection immunoanalysis (FIIA) methods are described. De-ethylatrazine, the major metabolite of atrazine, was chosen as representative analyte and was dissolved in ethanol. For the dipstick format, antibodies were immobilized on a nylon membrane. For the FIIA method, microglass beads (diameter 50-100 µm), surface modified with carboxylic groups, were used as support. Horseradish peroxidase was used as tracer and goat anti-rabbit IgG as primary antibody. The dipstick format gave a measurement range of 0.1-10 µg/l de-ethylatrazine, the FIIA 0.01-10 µg/l. Both formats enabled water and liquid food samples to be measured without the need for enrichment or clean-up steps. For soil samples, two extraction steps can be eliminated from the normal requirements for GC analysis. The two immunoassays gave results in good agreement with those from GC.
Atrazine Immunoassay Sensor Glass beads Immobilized enzyme Method comparison Nylon

"Speciation Of Cadmium(II) Using Donnan Dialysis And Differential-pulse Anodic-stripping Voltammetry In A Flow Injection System"
Int. J. Environ. Anal. Chem. 1990 Volume 41, Issue 3-4 Pages 133-148
Dan Berggren

Abstract: The method was applied to the determination of free Cd in the presence of its organic complexes. Sample and receiver solution of I = 0.1 M (NaNO3 as bulk electrolyte) were equilibrated in a Plexiglass dialysis cell (each channel 5 cm x 1.5 mm x 0.17 to 0.2 mm) with a sulfonated PTFE cation-exchange membrane and the receiver solution passed into a flow-cell fitted with a mercury-film electrode, a confined wall-jet vitreous-carbon electrode and a Ag - AgCl - 0.15 M KCl reference electrode. Polarography was at -0.8 V vs. Ag - AgCl with scanning at 10 mV s-1. Determination was via measurement of a constant fraction of the Cd ion associated with the membrane phase. Values obtained agreed well with theoretical values for citric, nitrilotriacetic or oxalic acid as ligand, but for fulvic acid varied widely with pH; results for two soil samples are discussed.
Cadmium(2+) Voltammetry Electrode Electrode Ion exchange Polarography Speciation Dialysis Nafion membrane Donnan dialysis

"Flow Injection System With Multisite Detection For Spectrophotometric Determination Of Calcium And Magnesium In Soil Extracts And Natural Waters"
J. Agric. Food Chem. 1996 Volume 44, Issue 1 Pages 165-169
Ana Rita A. Nogueira, Sandra M. B. Brienza, Elias A. G. Zagatto, Jos&eacute; L. F. C. Lima, and Alberto N. Ara&uacute;jo

Abstract: A flow system with a relocatable detector for spectrophotometric determination of calcium (Ca) and magnesium (Mg) in KCl soil extracts and natural waters is presented. O-Cresolphthalein complexon (CPC) was selected as the chromogenic reagent, ammonium-ammonia as the buffer system, and EGTA or 8-hydroxyquinoline as the masking agents for Ca or Mg, respectively. Linearity of the calibration equations was observed for Ca and Mg concentrations up to 80.0 and 15.0 mg/L, respectively. Slight variations in the coefficients of the calibration equations (usually <3%) were found after 4-h working periods. Recoveries between 97.5 and 104.1% were calculated after adding 10.0 mL of Ca at 15.00 mg/L or Mg at 5.00 mg/L Mg to 50.0 mL sample solutions. Precise results (relative standard deviation, <0.02) in agreement with flame atomic absorption spectrometry were obtained. With multisite detection, washing time was not a relevant factor in sampling rate, and an improved sample throughput of 160/h (corresponding to 0.8 mg of CPC per sample) was obtained.
Calcium Magnesium Spectrophotometry 8-Hydroxyquinoline

"Methods Of Separation And Determination For The Examination Of Binding Forms Of Metals In Soil Solutions"
Fresenius J. Anal. Chem. 1983 Volume 316, Issue 4 Pages 390-396
Georg Schwedt, Kristin Wedepohl, Dieter Z&ouml;ltzer

Abstract: In order to characterize binding forms of metals in soil solutions, photometric (continuous-flow- or flow injection system for Al or Fe) and polarographic (Fe, Mn) methods are applied for labile metal-species groups. Examination of different ion-exchange materials shows that the highest exchangeability (for Al, Fe, Mn, Zn) is attained by application of chemically-modified silica gel with benzenesulfonic acid groups. This type of modified silica gel is also the ion-exchanger with the lowest rate of adsorption for organic compounds. Gelpermeation- and reversed-phase HPLC are suitable for characterisation of the organic compounds. The results show that a high proportion of the labile iron that is photometrically detectable with ferrozine, exists in the form of organic and anionic complexes. The methods presented are suitable for combined use with other methods, and can be adjusted to suit eco-chemical problems.
Aluminum Iron Sample preparation Spectrophotometry

"Cold Vapor Generation For Inductively Coupled Argon Plasma Atomic-emission Spectrometric Analysis. 3. Mercury"
J. AOAC Int. 1994 Volume 77, Issue 2 Pages 473-480
Anderson, K.A.;Isaacs, B.;Tracy, M.L.;Moller, G.

Abstract: Sample was digested with concentrated HNO3 and K2CrO4 for 6-12 h at room temperature and then for 24 h at 95°C, and the digest was treated with enough saturated KMnO4 solution to surpass the endpoint, which is recognized when the solution remains a clear purple or a brown precipitate remains after mixing. The mixture was heated at 70-95°C for 10 min then treated dropwise with saturated oxalic acid solution until it became clear and colorless or, for soils the samples changed from dark brown to milky white, and vortex-mixed. The resulting solution was mixed with 10 M HCl and 6% NaBH4 in 5% NaOH in a continuous-flow manifold (diagram given) and subjected to ICP-AES with measurement at 194.232 nm. The instrumental detection limit was 0.2 µg/l. The method was used to analyze biological materials and environmental materials, including plants, soil and water (which was analyzed directly). Recoveries were 68.4-97.0%.
Mercury(II) Sample preparation Spectrophotometry

"Determination Of Total Arsenic And Selenium In Soils And Plants By Atomic Absorption Spectrometry With Hydride Generation And Flow Injection Analysis Coupled Techniques"
J. AOAC Int. 1996 Volume 79, Issue 3 Pages 764-768
Oroncio Jim&eacute;nez De Blas, N. Rodriguez Mateos, and A. Garcia Sanchez

Abstract: Plant and soil samples were wet digested using a Kjeldahl metal digestion block operated with temperature programming and a microwave oven. Total As and Se were reduced with NaBH4 and concentrated HCl, respectively, (optimized conditions are tabulated). Analysis was by AAS with use of a Varian-AA-1475 spectrophotometer equipped with an air-acetylene flame (operating parameters tabulated) with measurements at 193.7 and 196 nm for As and Se, respectively. Detection limits were 1 µg/ml for both elements for a sample volume of 160 µL with RSD of 3-6%. For the reference materials FD8 and MRG-1, the recoveries ranged from 93-105%. A procedure has been developed for determination of total arsenic and selenium in soils and plants by atomic absorption spectrometry with hydride generation associated with flow injection analysis (FIA-AAS-HG). Samples were wet-digested by using 2 systems: heating in a metal digestion block with controlled temperature and time and heating in a microwave oven, Total arsenic and selenium were reduced with NaBH4 and concentrated HCl, respectively, In both digestion systems used for the 2 matrix types, detection limits below 1 µg/L were found for both elements for an injection volume of 160 µL, with relative standard deviations of 3-6%, Recoveries by the method ranged from 93 to 105%; with the reference materials FD8 and MRG-1, the values obtained in all cases were consistent with the certified data. The FIA-AAS-HG procedure is highly suitable for determination of total arsenic and selenium in soils and plants, and because of the coupled system used, it is an improvement over other procedures in terms of sample treatment, sample consumption, and automation.
Arsenic, total Selenium, total Sample preparation Sample preparation Spectrophotometry Interferences Reference material Kjeldahl

"Liquid Chromatographic Method For Quantitation Of Glyphosate And Metabolite Residues In Organic And Mineral Soils, Stream Sediments And Hardwood Foliage"
J. AOAC Int. 1989 Volume 72, Issue 2 Pages 355-360
Thompson DG, Cowell JE, Daniels RJ, Staznik B, MacDonald LM

Abstract: Soil, sediment, foliage and deposit collectors (polyethylene sheets) were extracted with aqueous 0.5 M NH3 and the extract was applied to an AG 1-X8 anion-exchange column, with elution with 0.5 M NH4HCO3. After removal of bicarbonate by repeated evaporation and dissolution in water, further cleanup was effected on a Dowex 50W-X8 cation-exchange column. The aqueous eluate was evaporated to dryness and the residue was dissolved in 5 mM KH2PO4 for HPLC on a column (10 cm x 4.6 mm) of Aminex A-9 equipped with a guard column of the same material and operated at 50°C with 5 mM KH2PO4 (pH 1.9) buffer in aqueous 4% methanol as mobile phase (0.5 mL min-1). After post-column derivatization with ninhydrin at 100°C, glyphosate (I) and its metabolite aminomethylphosphonic acid (II) were detected at 570 nm. Calibration graphs were rectilinear for 0.05 to 3.0 µg of I and 12.5 to 750 ng of II, and detection limits ranged from 0.01 to 0.1 µg g-1.
Glyphosate LC Sample preparation Column Dissolution rate Post-column derivatization Calibration Detection limit Extraction

"Using FIMS To Determine Mercury Content In Sewage Sludge, Sediment And Soil Samples"
J. Autom. Methods Manag. Chem. 1996 Volume 18, Issue 6 Pages 221-223

Abstract: Sewage sludge (0.01 g) spiked with Hg was weighed into a digestion flask, moistened with a few drops of water and 21 mL HCl and 7 mL HNO3 were added. Digestion was carried out in accordance with DIN 38414, Part 12. The cooled solution was diluted to 100 mL with water. A portion (100 µL) of 0.5% K2Cr2O7 in HNO3/H2O (1:1) was added to 1 mL supernatant and the mixture was diluted to 10 mL. Samples were reduced with 1.5% SnCl2 in 1% HCl prior to Flow injection Mercury Systems (FIMS) analysis. Recoveries of Hg in spiked sewage sludge were 96-100% and analyzes of standard reference samples were in agreement with certified values. RSD (n = 3) were ~2% for 10 µg/l of Hg. Results obtained by FIMS were in agreement with values obtained by FIA generation of Hg vapor and AAS.
Mercury Spectrophotometry Sample preparation FIMS Volatile generation Method comparison Reference material Volatile generation

"Autocatalysis In The Spectrophotometric Flow Injection Determination Of Manganese As Permanganate. Soil, Plant And Rock Analysis"
J. Braz. Chem. Soc. 1990 Volume 1, Issue 1 Pages 28-34
M. Mesquita, A O Jacintho, E. A G. Zagatto and R. F. Antonio

Abstract: Periodate oxidation was carried out under acidic conditions at ~95°C. The reaction rate was accelerated by exploiting the autocatalytic effect which was enhanced with addition of a permanganate confluent stream. Reagent concentration, permanganate addition, level, acidity, flow rates, color stability and interference effects were studied. Hydrochloric acid was tolerated up to 0.5M. Detection limit was ~0.3 mg L-1 Mn. Analysis time was 60 h-1. Results agreed well with those obtained by AES.
Manganese Permanganate Spectrophotometry Catalysis Interferences Detection limit Method comparison Heated reaction

"Spectrophotometric Determination Of Ammonium Ion In Soil And Water By Flow Injection Analysis"
J. Chem. Soc. Pak. 1997 Volume 19, Issue 4 Pages 313-316
Yaqoob, M.;Nabi, A.;Wahab, A.;Kasi, I.

Abstract: The system involved two streams of flow rate 0.6 ml/min: one consisting of 0.15 M phenol and 0.05% sodium nitroprusside; the other consisting of 3% sodium hypochlorite and 0.1 M sodium hydroxide (schematic given). Sample (30 l) was injected into the first stream via a T-piece after which both streams merged and after passing through a heated mixing coil (200 cm x 0.5 mm i.d.), maintained at 40°C by a water bath, the absorbance was measured at 640 nm. Beer's law was obeyed from 4-24 ppm ammonium ion with an RSD of 0.6-1.2% (n = 6) at a sampling rate of 30/h. The air-dried soil was initially extracted with water forming a paste, left for 3 h and then centrifuged to obtain a solution for injection into the FIA system.
Ammonium Spectrophotometry

"Rapid Determination Of HClO4-H2SO4 Degradation Nitrogen And Phosphorus In Farm Soils, Crops And Organic Manure Using Flow Injection Analysis"
J. Flow Injection Anal. 1993 Volume 10, Issue 2 Pages 224-235
Hideharu Nakajima *Ryoichi Yanagihara

Abstract: Sample (0.5 g) was decomposed with 25 mL of water, 3 mL of concentrated H2SO4 and 20.5 mL of HClO4 at 130°C for 10 min then heated to fuming at 200°C for 50 min. After cooling, water was added until the total weight was 50 g. To determine N, 30-200 µL of the supernatant was injected into the flow injection analyzer. and carried by a stream of 6% H2SO4 at 0.8 ml/min to mix with 2.5 M NaOH at 2 ml/min in a reaction tube at 30°C prior to reacting with a stream of Tecator NH3 indicator and detection at 590 nm. For P, 30-200 µL of the supernatant was carried by 6% H2SO4 at 2 ml/min to mix successively with 31 g/l of ammonium molybdate solution at 2.8 ml/min, water at 0.8 ml/min and 2% ascorbic acid at 0.8 ml/min with detection at 660 nm. For other samples vanadomolybdic acid was used instead of ammonium molybdate solution and ascorbic acid treatment, with detection at 420 nm. RSD for N and P were 2.1-5.4 and 1.8-8.6%, respectively. The results compared well with those obtained by other conventional methods.
Phosphorus Nitrogen Spectrophotometry Sample preparation Method comparison Tecator

"Sequential Injection Analysis With Accuracy Assessment"
J. Flow Injection Anal. 1998 Volume 15, Issue 2 Pages 226-233
Zagatto, E.A.G.;Vicente, S.;Oliveira, C.C.;Sartini, R.P.;Lima, J.L.F.C.

Abstract: Two quasi-independent methods for spectrophotometric determination of aluminum in soil extracts, based on Al(III) complexation with Aluminon and Chromazurol S (CAS), are implemented in a SIA system. Because results are based on both methods, accuracy assessment is provided. Potentialities and limitations of the approach are discussed. The proposed system is robust and yields reproducible measurements (RSD <5% for 2.0-10.0 mg L-1 Al) at a 15 h-1 rate. About 85 µg of Aluminon and 13 µg CAS are consumed per determination For atypical samples, interference effects are promptly observable.
Aluminum(III) Sample preparation Spectrophotometry Interferences Sequential injection Complexation Accuracy

"Radiochemical Method Development"
J. Hazard. Mater. 1995 Volume 41, Issue 2-3 Pages 351-358
Mitchell D. Ericksona,*, Joseph H. Aldstadta, Jorge S. Alvaradoa, Jeffrey S. Crainb, Kent A. Orlandinia and Lesa L. Smithb

Abstract: We have developed methods for chemical characterization of the environment under a multi-task project that focuses on improvement of radioanalytical methods with an emphasis on faster and cheaper routine methods. We have developed improved methods for separation of environmental levels of technetium-99, radium, and actinides from soil and water; separation of actinides from soil and water matrix interferences; and isolation of strontium. We are also developing methods for simultaneous detection of multiple isotopes (including nonradionuclides) by using a new instrumental technique, inductively coupled plasma-mass spectrometry (ICP-MS). The new ICP-MS methods have greater sensitivity and efficiency and could replace many radiometric techniques. We are using flow injection analysis to integrate and automate the separation methods with the ICP-MS methodology. The objective of automating methods is to achieve more reproducible results, reduce labor costs, cut analysis time, and minimize secondary waste generation through miniaturization of the process. The final product of all activities will be methods that are available (published in the US Department of Energy's analytical methods compendium) and acceptable for use in regulatory situations.
Actinides Radium Technetium-99 Mass spectrometry Miniaturization Optimization Interferences

"A Study On The Determination Of N(NO2-), N(NO3-) And N(NH4+) In Environmental Samples By Flow Injection Analysis"
J. Korean Chem. Soc. 1997 Volume 41, Issue 5 Pages 256-265
Jae-Seong Rhee, Young-Sang Kim, Yun-Hee Jung, and Hee-Jung Rhee

Abstract: A rapid and sequential method was studied, which can determine nitrite, nitrate and ammonium ion in soil or water samples with flow injection analysis Geometric factors including injection volume, length of the reaction coil and flow rate of carrier solution were studied prior to sample measurement. Nitrite was determined at 540 nm by Griess reaction producing azo dye between N-(1-naphthylethylenediamine dihydrochloride) and sulfanilamide. Nitrate was also measured after reduction to nitrite with hydrazine. Ammonium was analyzed at 440 nm with Nessler's reagent. At the optimum condition, the detection limit (S/N = 3) was shown 0.1 µg/mL N(NO2-), 0.4 µg/mL N(NO3-) and 0.3 µg/mL N(NH4+) respectively. The results measured by colorimetry, ion chromatography and FIA were compared showing 80%-125% reasonable match each other. Injection throughput rate could be performed better than 30 time per h.
Nitrogen, ammonium Nitrogen, nitrate Nitrogen, nitrite Spectrophotometry Optimization Method comparison

"Analysis Of Oxothio Arsenic Species In Soil And Water"
J. Prakt. Chem. Chem. Ztg 1996 Volume 338, Issue 1 Pages 55-59
Georg Schwedt, Melanie Rieckhoff

Abstract: Arsenic species in alkaline extracts of sulfidic and arsenic slags as well as in water in mines were analyzed by ion chromatography and capillary zone electrophoresis. The total arsenic was determined in both kinds of samples by FIA-hydride AAS, in the slags after microwave induced pressure digestion, and in the untreated solid samples also by RFA. Arsenate, arsenite and monothioarsenate ions could be identified and quantified as stable arsenic species.
Arsenate ion Arsenothioate ion Arsenite Sample preparation Spectrophotometry Speciation Volatile generation Volatile generation

"Double-plunger Pump System Flow Injection Spectrophotometric Determination Of Inorganic Nitrogen In Soil Extracts. 1. Flow Injection Analysis Of Ammonium Nitrogen In Soil Extracts"
Jpn. J. Soil Sci. Plant Nutr. 1991 Volume 62, Issue 2 Pages 128-134

Abstract: A flow injection analytical system with a double-plunger pump in conjunction with the indophenol blue colorimetric method for the determination of NH4-N in potassium chloride soil extracts is described. A sample solution (30 µL) is injected into one color developing reagent (2.4% phenol + 0.01 % sodium nitroprusside + 0.1% EDTA + phosphate-citrate buffer solution) which acts as a carrier stream (1.0 ml/min), amd merges with the other color developing reagent (0.06% OCl- + 0.25 M KCl) stream from the other plunger pump. The mixture is then passed through a reaction coil (0.5 mm x 120 cm) in an air bath at 80°C to develop the indophenol blue complex. The precision at 0.4 and 4.0 ppm NH4-N was 1.11 and 0.7%, respectively. Determined values agreed well with those obtained by a distillation-titration method.
Nitrogen, ammonia Spectrophotometry Sample preparation Apparatus Pump Method comparison

"Double-plunger Pump System Flow Injection Spectrophotometric Determination Of Inorganic Nitrogen In Soil Extracts. 2. Flow Injection Analysis Of Nitrate Nitrogen In Soil Extracts"
Jpn. J. Soil Sci. Plant Nutr. 1991 Volume 62, Issue 2 Pages 135-140

Abstract: A flow injection system of analysis based on the cadmium reduction-diazo coupling colorimetric method for the determination of NO3-N in potassium chloride soil extracts is described. A sample solution (30 µL) is injected into a reagent (1 mM EDTA + 0.1 M KCl + 0.5 mM HCl) which acts as the carrier stream (0.75 ml/min) and passed through a copperized cadmium column (4 mm x 5 cm; particle size, 0.5-2 mm) to convert nitrate to nitrite quantitatively. Then, the carrier solution is merged into the stream of a color developing reagent (0.02% p-aminoacetophenone + 0.055% m-phenylendiamine + 24 mM HCl) from the other channel. The mixture passes through a reaction coil (0.5 mm x 120 cm) in an air bath at 50°C for the diazo coupling reaction to proceed. The precision at 0.4 and 4.0 ppm NO3-N was 0.4 and 0.6%, respectively. Determined values agreed well with those obtained by a distillation-titration method.
Nitrogen, ammonia Spectrophotometry Sample preparation Method comparison

"Determination Of Trace Amounts Of Selenium In Environmental Samples By Hydride-generation Atomic Absorption Spectrometry Combined With The Flow Injection Analysis Technique"
Kexue Tongbao 1986 Volume 31, Issue 11 Pages 791-792

Abstract: The methodology and apparatus for a hydride-generation AAS - flow injection analysis system is described. The system is used for the determination of Se in soil, plants or waste waters. An aliquot of the homogenized sample was injected into 2 M HCl as carrier solution (12 mL min-1) and mixed in the mixing coil. The Se was reduced with NaBH4 at 2 mL min-1 in the reaction coil and the H2Se and H were mixed with Ar as carrier gas (150 mL min-1) and swept into a gas - liquid separator for H2Se to be determined by AAS at 700°C. The detection limit for Se was 0.07 ng mL-1 and the coefficient of variation was <2%.
Selenium Spectrophotometry Phase separator

"Flow Analysis Techniques In Environmental Analysis"
LaborPraxis 1993 Volume 17, Issue 9 Pages 56-57
Thiele, M.

Abstract: The past and present of FIA and continuous-flow analysis are discussed. These methods are somewhat overshadowed by ion chromatography, although DIN officially recognizes the determination of NH3 (DIN 38406) and DIN 38405 contains two draft recommendations for determination of nitrate and nitrite; the standardization of the determination of phosphate by the molybdenum blue method is also being considered. Future possibilities are chloride, cyanide and phenol index determinations. One of the advantages can be integrated pre-treatment (dialysis for biological or soil samples, or distillation for determination of fluoride, phenol or cyanide). Continuous-flow analysis is recommended in most instances, except for phenols or detergents, for which FIA seems preferable. At present, micro-continuous-flow systems with parts of i.d. 1 mm are also available.
Review Dialysis

"Automated Photometric Determination Of The Activity Of Soil Enzymes By Applying Oxidative Coupling Reactions In Continuous-flow. 2. Determination Of The Activity Of Saccharase"
Landwirtsch. Forsch. 1986 Volume 39, Issue 3 Pages 245-259
Holz, F.

Abstract: A semi-automated method is described for the assay of β-fructofuranosidase in soil. Soil is buffered to pH 5.5, sucrose is added (as substrate), and the mixture is incubated for 3 h at 37°C. The glucose formed is oxidized to gluconic acid and H2O2 by glucose oxidase. The H2O2 is used as an oxidizing agent for oxidative coupling, with peroxidase as catalyst, of 4-aminoantipyrine and 3-dimethylaminobenzoic acid to form a red indamine dye. The coefficient of variation (n = 5) are 0.40 to 0.78%.
Enzyme, saccharase Sample preparation Spectrophotometry Enzyme

"Automated Photometric Determination Of The Activity Of Soil Enzymes By Applying Oxidative Coupling Reactions In Continuous-flow. 1. Determination Of The Activity Of Catalase"
Landwirtsch. Forsch. 1986 Volume 39, Issue 1-2 Pages 139-153
Holz, F.

Abstract: A sample (1 g) of moist soil is mechanically shaken in a closed screwtop vessel for 30 min at room temperature with 20 mL of 0.1 M phosphate buffer (pH 7) and 2 mL of a solution of 6.79 g of sodium perborate in 500 mL of the phosphate buffer. After 30 min, the reaction is stopped by the addition of 3 mL of aqueous 3.5% NaN3; the solution is filtered and the excess of H2O2 is determined photometrically at 550 nm in an automated flow-through analyzer. (described in detail), by means of the red indamine dye formed by the oxidative coupling of 4-aminoantipyrine and 3-dimethylaminobenzoic acid catalyzed by peroxidase. The blank value is determined by treating the sample with 3 mL of the NaN3 solution before reaction with sodium perborate as described above. The coefficient of variation of the determination of H2O2 was 0.09 to 0.25%, that of the catalase activity (n = 5) was 5.1%. As expected, the catalase activity is closely related to the organic content of the soil, and decreases with the depth at which the sample is taken. The soil sample was buffered at pH 7.0 and incubated for 30 min with a solution of NaBO2.H2O2.3H2O, then NaN3 was added to stop the enzymatic reaction. 4-Aminoantipyrine and 3-dimethylaminobenzoic acid were coupled oxidatively, with the residual H2O2 as oxidant and peroxidase as catalyst, to form an indamine dye, the absorbance of which was measured at 550 nm. By using a continuous-flow system, 30 determinations in 1 h were possible. Decomposition of H2O2 was rectilinear for sample wt. of 0.5 to 2 g and incubation times of 10 to 50 min; 1 g and 30 min were chosen for the assay. The coefficient of variation averaged 0.15% for the determination of H2O2 and 5.1% for the complete catalase assay.
Enzyme, catalase Sample preparation Spectrophotometry Enzyme

"Flow Injection Catalytic Spectrophotometric Determination Of Trace Manganese By Use Of The Reaction System Nitrilotriacetic Acid-manganese(II)-fuchsine-potassium Periodate"
Lihua Jianyan, Huaxue Fence 1994 Volume 30, Issue 2 Pages 86-88
Zi, Y.Q.;Chen, L.G.;Zeng, Q.G.

Abstract: Mn(II) solution (0.1 ml) was injected into the flow injection analyzer. to mix with a stream of 0.12 mM basic fuschine before further mixing and reaction with streams of 0.2 M acetic acid/0.2 M sodium acetate buffer of pH 4.5, 3 mM nitrilotriacetic acid and 15 µM-KIO4 (all streams at 2.52 ml/min) in a 130 cm reaction tube in a constant-temp. bath of 75°C, cooling in a 40 cm tube with running water as coolant and measurement of the decreased absorbance at 540 nm. The response was linear for up to 0.35 µg/ml, and the detection limit was 0.3 ng/ml. There was no interference in the determination of 0.1 µg/ml of Mn. The sampling frequency was 24 per h. The method was applied to environmental water, soil and cereals, including wheat and beans, with RSD of 1.3%.
Manganese Spectrophotometry Catalysis Heated reaction Interferences

"Use Of Reactors Involving Complexation In Flow Injection Systems"
Magy. Kem. Foly. 1994 Volume 100, Issue 9 Pages 450-458
Graf Harsanyi, E.

Abstract: The behavior of CuS and Ag2S ppt.-based electrode membranes in the presence of complexing ligands is discussed. Possibilities of the determination of complexing agents were studied. Complexing agents forming stable complexes with Cu or Ag give characteristic potentiometric calibration curves for the ligands. The indirect determination of complexing agents in a FIA AAS system is also possible by using a reactor tube in the flow system. The reactor tube is filled with CuS or Ag halide ppt. Some practical applications are also given. (SFS)
Spectrophotometry Potentiometry Electrode Spectroelectrochemistry Indirect Complexation Reactor

"Determination Of The Aluminum Complexing Capacity Of Fulvic Acids And Natural Waters, With Examples From 5 New-zealand Rivers"
Mar. Fresh. Res. 1996 Volume 47, Issue 1 Pages 11-17
DJ Hawke, KJ Powell and JE Gregor

Abstract: An FIA technique with 7 s reaction time was used to analyze free plus labile Al in fulvic acid (FA) solutions and natural waters at pH 4.7, without the need for separation procedures. Titrations of these solutions using incremental pH or total Al were used to determine pH binding curves or estimates of the 'kinetic' Al complexation capacity (Al-CCk) respectively. The operational definition of Al-CCk relates to the capacity of a humic substance or natural water to bind Al through a 7-s FIA reaction time under defined experimental conditions of chromophore (GAS) concentration, ionic strength, and pH. Both Al binding strength and complexation capacity were greater than the corresponding Cu-CC (ISE) values. The Al-CCk measurements at pH 4.7 were 710 µmol Al g-1 v. 590 µmol Cu g-1. Al-CCk results (pH 4.7) were higher for soil FA (710 µmol g-1) than for aquatic FA (390 µmol g-1). AI-CC, results (pH 4.7)for five unfiltered river waters from different catchments gave results in the range 6.5-9.8 µmol Al L-1. The differences between total (natural) Al in the samples and Al-CCk were between 2.7 µM and 8.6 µM. Filtration experiments identified fractionation patterns between total (natural) Al and the fraction of Al-CCk not utilized. The Al titration of alginate, another component of natural organic matter, is reported.
Aluminum Alginate Voltammetry Speciation Complexation Speciation Titrations

"Fundamentals And Applications Of Flow Injection Analysis. 2. Application Of The Method"
Jpn. J. Soil Sci. Plant Nutr. 1987 Volume 58, Issue 2 Pages 247-251
Koshino, Masayoshi

Abstract: A review on the application of flow injection analysis to soils and fertilizers. Determination of phosphorus, NH4+, NO2-, NO3-, SO42-, etc. with various detection systems such as spectrophotometry, electrochemical methods, atomic absorption spectrometry, and ICP-AES were explained. 29 references.
Phosphorus Ammonium Nitrate Nitrite Sulfate Spectrophotometry Spectrophotometry Spectrophotometry Electrochemical analysis Review

"Determination Of Nitrogen In Plant And Soil By Flow Injection Analysis"
J. Penel. Peng. Pert. 1988 Volume 8, Issue 1 Pages 15-NA
Rahardjo, M.;Nakajima, H.;Ichiki, H.

Abstract: NA

"Techniques For Boron Determination And Their Application To The Analysis Of Plant And Soil Samples"
Plant Soil 1997 Volume 193, Issue 1-2 Pages 15-33
Ram N. Sah and Patrick H. Brown

Abstract: This paper reviews techniques for determining B concentration and isotopic ratio and their application to soil and plant samples. Boron concentration has been determined utilising spectrophotometry, potentiometry, chromatography, flame atomic emission and absorption spectrometry, inductively coupled plasma (ICP) optical emission (OES) and mass spectrometry (MS), and neutron activation analysis using neutron radiography and prompt-γ activation analysis. Isotopic ratios of B have been measured by ICP-MS, thermal ionisation mass spectrometry (TIMS) and secondary ion mass spectrometry (SIMS). For isotopic measurements, TIMS and SIMS are more sensitive and provide higher degrees of accuracy and resolution than ICP-MS, however, extensive sample preparation and purification, and time-consuming measurements limit their usefulness for routine analyzes. 204 References
Boron Sample preparation Mass spectrometry Mass spectrometry Spectrophotometry Potentiometry Review

"Analytical Methodology For The Determination Of Aluminum Fractions In Natural Fresh Waters"
Pure Appl. Chem. 1996 Volume 68, Issue 8 Pages 1597-1638
N. Clarke, L.-G. Danielsson and A. Sparen

Abstract: The distribution among different species, ''speciation'', is essential for understanding the toxicity, bioavailability and transport mechanisms for elements in the natural environment. The distribution of Al among different species has been in focus during the last twenty years or so, and many methods for fractionating Al have been developed. Most of them are operationally defined, since validation of what is really measured in natural systems is very difficult. This review is a thorough and critical survey of the existing methods for Al fractionation in natural waters, that covers the literature up to and including June, 1994. The methods have been classified into six groups, according to the principles used: 1) Kinetic or Binding Strength Discriminations; 2) Ion Chromatographic Separations; 3) Size Exclusion; 4) Non-Invasive Methods; 5) Ion Mobility in an Electric Field; 6) Minimized Disturbance. In addition to this, in order to validate the different techniques, we scrutinize some of the method comparisons published.
Aluminum Chromatography HPIC SEC Nuclear magnetic resonance Chelation Speciation Review

"Determination Of Hydride-forming Elements At Ultratrace Levels By Flow Injection Hydride-generation Atomic Absorption Spectrometry With Online Ion-exchange Column Preconcentration"
Quim. Anal. 1989 Volume 8, Issue 2 Pages 191-199
Zhang, S.;Xu, S.K.;Fang, Z.L.

Abstract: Soil samples, prepared by refluxing for 2 h, and acidified, filtered water samples were merged with ammonium acetate buffer solution (0.2 M at pH 5 or 1 M at pH 7 for Se or Bi, respectively) and pre-concentrated on dual ion-exchange columns of D-201 (60 to 100 mesh) for Se(IV) or CPG-8Q (60 to 100 mesh) for Bi(III), and eluted with 1 M HCl. The eluates were mixed with 0.5% NaBH4 solution in 0.1% NaOH as reductant and carried by Ar carrier gas into a heated silica atomizer for AAS analysis. The limits of detection were 0.002 and 0.001 µg L-1 for Se(IV) and Bi(III), respectively, and the corresponding coefficient of variation were 1.1 and 1.0% (n = 11). Effects of co-existing ions are tabulated; interference from Cu(II) was overcome by the addition of 0.5% thiourea to the HCl eluent. Overall recoveries from water and soil water extracts were 90 to 108%, except for Bi(III) in waste water (78 to 90%).
Selenium Bismuth Ion exchange Sample preparation Spectrophotometry Column Preconcentration Buffer Interferences Volatile generation Nebulizer Ultratrace Volatile generation

"Determination Of Soluble Sulfate In Soils By Use Of A Filtration Probe Coupled With A Flow Injection System"
Quim. Anal. 1994 Volume 13, Issue 3 Pages 121-125
Zhi, Z.L.;Rios, A.;Valcarcel, M.

Abstract: The design and operation of a continuous flow filtration unit, coupled online with a dual-injection manifold assembled for the turbidimetric determination of sulfate using Ba reagent, is described. The unit also functions as a filtration probe, designed to simplify sample pretreatment to only involve weighing and suspension in water. The clear filtrate obtained, containing the soluble sulfate from the soil, was fed continuously to the loop of one of the injection valves located in the flow manifold; the turbidity generated was measured at 400 nm using peak height values. The system used the merging-zones approach to provide a stable baseline and reproducible results. The effects of FIA and chemical variables were studied and optimized. The effects of potential inorganic interferents were negligible; potential organic interferents were removed using water-washed charcoal. Calibration graphs were linear for 0-180 mg/l of sulfate with a detection limit of 2 mg; the RSD (n = 10) was 0.85%. The effects of interferences are discussed and tabulated. Results (tabulated) compared well with those of the reference method.
Sulfate Turbidimetry Filter

"Turbidimetric Determination Of Sulfate In Soils By Using Flow Injection Analysis"
Rev. Bras. Cienc. Solo 1990 Volume 14, Issue 2 Pages 119-124
De Andrade, J.C.;Friguetto, S.R.;Baccan, N.;Cantarella, H.;Bataglia, O.C.

Abstract: Turbidimetric determination of sulfate by flow injection analysis (FIA) with alternating streams (Krug, F. J. et al., 1983) was optimized for use in soil analysis. A solution of 0.01 M Ca(H2PO4)2 was used as carrier and diluent in preparation of standard solutions and for soil extraction Use of 20%(w/v) BaCl2 in 0.05% poly(vinyl alcohol) as precipitation agent improved reproducibility. Under the best experimental conditions, the calibration curve was linear in the range of 3.0-45.0 µg SO42-/L, and 70 samples could be analyzed per h. The degree of interference by Al(III), Mg(II), Fe(III), and Mn(II) varied with the level of sulfate in solution, but the max. observed variation of the signal was 10%. Analysis of nine soils by manual and FIA turbidimetric methods gave comparable sulfate contents and precision of the determinations, but FIA was faster and consumed less reagent and sample. (SFS)
Sulfate Turbidimetry Method comparison Interferences Optimization

"Flow Injection Determination Of Ammonium And Nitrate In Soil By The Diffusion Conductivity Method"
Rev. Bras. Cienc. Solo 1992 Volume 16, Issue 3 Pages 325-329
Coelho, N.M.M.;Cantarella, H.;De Andrade, J.C.

Abstract: An alternative procedure is proposed for the determination of ammonium and nitrate in soils using a flow injection analysis (F.I.A.) system, operated in a single line configuration with conductivity detection. This procedure allows the determination of NH4+ and NO3-, separately, with reactions producing ammonia, which is separated from the reaction medium by gaseous diffusion and transferred to a receiving stream of boric acid. The ammonia is converted to NH4+ ions and quantified by conductivity measurements. Under the experimental conditions, the calibration graphs for both NH4+ and NO3- are linear, up to 7.5 and 5.0 µg/ml, respectively. The method allows a sampling rate of 90 determinations per hour with a precision of `1% for NH4+ and NO3-. This method, which is free from interference, was applied to soil samples, using a 1.0 M KCl extracting solution. The results compared favourably with those obtained by the steam distillation procedure, with the F.I.A. system showing better precision.
Nitrate Ammonium Conductometry Method comparison Interferences Gas diffusion

"Determination Of Carbamate Pesticides By High Performance Liquid Chromatography (HPLC) With Post-column Derivatization"
Sepu 1994 Volume 12, Issue 1 Pages 32-34
Jiang Xinmin, Cai Daoji and Hua Xiaome

Abstract: A methanolic solution (1 ml) of six carbamate insecticides and three metabolites (listed) was subjected to HPLC on a column of Radial Pak C18 with gradient elution (1 ml/min) with aqueous methanol (details given). The eluate was mixed with a stream of o-phthalaldehyde/mercaptoethanol in 0.05 M Na2B4O7 and a stream of 0.05 M NaOH at 95°C (both 0.5 ml/min). The resulting insecticide derivatives were detected by fluorimetry at 455 nm (excitation at 338 nm). Calibration graphs were linear, the determination limit was 2 µg/l and the detection limit was 2 ng. The method was applied to analysis of natural waters and soil.
Pesticides, carbamate HPLC Fluorescence Post-column derivatization

"Determination Of Assimilable Phosphorus In Soils By Reversed-flow Injection Analysis"
Soil Sci. 1991 Volume 151, Issue 5 Pages 349-354
Perez Garcia, M.;Puchades, R.;Maquieira, A.

Abstract: Soil was extracted with 0.5 M NaHCO3 and the extract was diluted with water. The resulting solution was used as the carrier stream (3.3 mL min-1) in a reversed-flow injection analysis system, into which were injected 0.015% SnCl2 in 4 mM HCl (2.6 mL min-1) and 0.3% molybdate reagent (24 mM molybdic acid - 0.4N-HNO3 and 0.1% antimony - potassium tartrate; 3.3 mL min-1). The solution was passed through a reaction coil (75 cm x 0.8 mm) before the absorbance was measured at 660 nm. The calibration graph was rectilinear for 0.8 mg L-1 of P; the detection limit was 0.025 mg l-1. Sampling frequency was 70 h-1 and recoveries were quantitative.
Phosphorus Sample preparation Extraction Reverse

"Flow Injection Simultaneous Determination Of Basic Cation Pairs In Soils"
Soil Sci. 1995 Volume 159, Issue 5 Pages 331-336

Abstract: The use of flow injection analysis (FIA) to perform automatically the simultaneous determination of the pairs K/Ca, Ca/Mg, Na/K, and Na/Mg in soils is reported. A dialysis unit was used to divide the sample plug into two different streams and also to create large dilution capacity. After appropriate treatment inside the manifold, the resulting plugs were directed to two detectors placed in parallel, thus allowing bicomponent analysis. Atomic absorption and flame emission spectrometry were used as detection processes. The results obtained for an average of 25 soil samples by the developed FIA systems were in good agreement with those provided by the reference methods, i.e. the relative deviations were no larger than 3%. Sampling rates from 80 to 120 determinations/h, and relative standard deviations below 3%, were obtained.
Potassium Calcium Magnesium Sodium Spectrophotometry Spectrophotometry Dialysis Method comparison

"Flow Injection Analysis Of Nitrate In Soil Extracts: Evaluation Of A Nitrate-selective Flow Electrode Method"
Soil Sci. Soc. Am. J. 1981 Volume 45, Issue 2 Pages 446-448
E. B. Schalscha, T. Schirado and I. Vergara

Abstract: Nitrate (NO-3-) in soil saturation extracts was determined by a flow injection analysis (FIA) procedure and the results evaluated by comparing with the reduction-distillation and the Cd-reduction methods. FIA using a NO-3--specific end-window flow electrode designed by Ruzicka and Hansen gave the same results as the other 2 methods. The range of application is from 0.5-100 µg/ml of NO-3-N. The method is simple and rapid. More than 20 samples/h can be determined. The FIA is appropriate for soil extracts and water analysis.
Nitrate Electrode Electrode Sample preparation Method comparison

"Simultaneous Determination Of Urea- And Ammonia-nitrogen In Soil Extracts And Water By High Performance Liquid Chromatography"
Soil Sci. Soc. Am. J. 1988 Volume 52, Issue 4 Pages 969-973
A. Abshahi, S. S. Goyal and D. S. Mikkelsen*

Abstract: A HPLC system is described that utilizes three columns, viz, a guard column of Pellicular refill media - silica, a column of Partisil 10 SCX cation-exchange resin for separation of NH4+, and a column of urease - Nucleosil for catalysis of the hydrolysis of urea to NH4+. The mobile phase is 20 mM KH2PO4 of pH 6.9, and the NH4+ is detected fluorimetrically, after post-column derivatization with phthalaldehyde, at 455 nm (excitation at 344 nm). This rapid method can be applied in analysis of soil, water and fertilizers. Recoveries were almost quantitative.
Ammonia, nitrogen Urea HPIC Fluorescence Sample preparation Catalysis Immobilized enzyme Post-column derivatization

"Ion-chromatographic Determination Of Total Metals In Soils"
Soil Sci. Soc. Am. J. 1990 Volume 54, Issue 5 Pages 1289-1297
N. T. Basta and M. A. Tabatabai*

Abstract: Surface soil samples (2 g) were digested sequentially with concentrated HNO3, HClO4 and HF. The HF treatment was repeated until dissolution was complete. An aliquot (25 ml) of the resulting solution was treated with ammonium citrate buffer (5 ml), hydroxylammonium chloride solution (2 ml) and pyridine (2.5 ml). The solution, pH adjusted to 9.5 with 10 M NaOH, was extracted with 0.2% of dithizone in CHCl3 (2 x 15 ml). The combined extracts were evaporated to dryness and the residue was treated with concentrated HNO3 (3 ml) and again heated to dryness. The residue was dissolved in 0.1 M HCl and analyzed on a HPIC-CS 5 column equipped with a HPIC-CG 5 guard column with buffered 4 mM 2,6-pyridinedicarboxylic acid (pH 4.8) or 40 mM oxalic acid (pH 4.8) as mobile phase (1 mL min-1). Post-column derivatization was achieved by mixing the column effluent with a stream of 0.01% ammoniacal solution of 4-(2-pyridylazo)resorcinol and 0.02% NN-dimethylethanolamine; the absorbance of the metal complexes was measured at 520 nm. Results obtained for Cu, Ni and Zn agreed with those obtained by AAS; low results were obtained for Cd, Mn and Pb. With oxalic acid as eluent, the detection limits were 5 µg L-1 for Cu and Zn and 20 µg L-1 for Ni; the coefficient of variation were 4.9% (n = 6).
Metals Copper Nickel Zinc Cadmium Manganese Lead HPIC Sample preparation Spectrophotometry Buffer Column Post-column derivatization Detection limit Method comparison Complexation Dithizone

"Flow Injection Analysis Of Urea Nitrogen In Soil Extracts"
Soil Sci. Soc. Am. J. 1991 Volume 55, Issue 1 Pages 109-113
D. M. Sullivan* and J. L. Havlin

Abstract: Flow injection analysis (FIA) is a relatively new technique with advantages over traditional automated analysis methods in precision and sample throughput. A new procedure has been developed to measure urea in soil extracts using automated FIA. This procedure utilizes the diacetyl monoxime thiosemicarbazide colorimetric method, with a modified acid reagent that increases the rate of color formation and improves the mixing of sample with reagent in narrow-diameter (0.8-mm) tubing. Sixty samples can be analyzed per hour, with a detection limit of 0.01 mg urea-N L-1. Residence time between sample injection and maximum absorbance is 130 s. The developmenht of an automated FIA system for the determination of urea-N in KCl extracts of soil is presented. The procedure utilizes the diacetyl monoxime thiosemicarbazide colorimetric method (cf. Butler and Walsh, Trends Anal. Chem., 1982, 1, 120) with a modified acid reagent (FeCl3.6H2O - H2SO4 - H3PO4) that increases the rate of color formation and improves the mixing of sample and reagent in narrow diameter (0.8 mm) tubing. The reaction takes place at 95°C; sixty samples can be analyzed per hour with a residence time of 130 s between sample injection and maximum absorbance at 520 nm. The calibration graph was rectilinear up to to 8 mg urea-N; the limit of detection was 0.01 mg L-1 and the coefficient of variation (n = 5) was 10%. Accuracy and precision were good. The FIA method is not affected by a variety of organic and inorganic N compounds, but is susceptible to interference by reducing agents.
Nitrogen, urea Spectrophotometry Sample preparation Automation Heated reaction Interferences

"Improving The Berthelot Reaction For Determining Ammonium In Soil Extracts And Water"
Soil Sci. Soc. Am. J. 1998 Volume 62, Issue 2 Pages 473-480
E. D. Rhine, G. K. Sims*, R. L. Mulvaney, and E. J. Pratt

Abstract: Colorimetric methods based on the Berthelot reaction are used widely for quantitative determination of NH4-N in biological and environmental samples. Studies to evaluate phenol and salicylate, the most commonly used chromogenic substrates, revealed minor interferences by metallic cations, whereas up to a threefold shift in absorbance was observed with 38 diverse N-containing organic compounds. Interferences differed markedly between phenol and salicylate. The possibility of a simple correction was precluded by the fact that interferences were both positive and negative, and depended on the temperature during color development and the concentration of NH4-N. Fourteen compounds were evaluated as alternatives to phenol and salicylate, of which the Na salt of 2-phenylphenol (PPS) proved to be the most promising. Using PPS, macro- and microscale batch methods and an automated flow injection method were developed. These methods are simple, convenient, and sensitive. Using the PPS microscale method, for which the limit of detection is 0.17 mg NH4-N L-1, recovery of NH4-N added to soil extracts ranged from 98 to 104%, with a coefficient of variation of 1.4 to 2.7%. As with phenol and salicylate, precipitation of metal hydroxides was observed. Precipitation was controlled by chelation with citrate rather than ethylenediaminetetraacetic acid (EDTA), which suppressed color development by preventing monochloramine formation. Compared with Berthelot methods that use phenol or salicylate, interference by amino acids was decreased by up to 10-fold. Interference by other organic N compounds was virtually eliminated.
Nitrogen, ammonium Sample preparation Spectrophotometry Interferences

"Applications Of Flow Injection To Samples Of Agricultural Interest"
Tec. Lab. 1985 Volume 9, Issue 120 Pages 18-24
Martinez Calatayud, J.

Abstract: A review is presented, with 50 references, of methods applicable to soil, plants, fertilizers and water.

"The Rapid Examination For Phosphate Fertility In Grazing And Farm Land Soil Derived From Neutral Volcanic Ash. 3. Application Of Flow Injection Analysis To 10 M H2S04 Extraction"
Tohoku J. Agric. Res. 1985 Volume 37, Issue NA Pages 135-136
Nakajima, H.;Ichiki, H.

Abstract: NA
Phosphate Sample preparation Extraction

"The Rapid Examination For Phosphate Fertility In Grazing And Farm Land Soil Derived From Neutral Volcanic Ash. 4. Application Of Flow Injection Analysis To NH4F- HCl Extraction"
Tohoku J. Agric. Res. 1985 Volume 37, Issue NA Pages 137-NA
Nakajima, H.;Ichiki, H.

Abstract: NA
Phosphate Sample preparation Extraction

"Rapid Method Of Determination Total Nitrogen In The Farm Soils By HCIO4-H2SO4 Digestion-flow Injection Analysis"
Tohoku J. Agric. Res. 1986 Volume 39, Issue NA Pages 143-NA
Nakajima, H.;Ichiki, H.

Abstract: NA
Nitrogen, total Sample preparation

"The Rapid Examination For Phosphate Fertility In Grazing And Farm Land Soil Derived From Neutral Volcanic Ash. 6. Rapid Determination Of Phosphate Absorption Coefficient Using The Flow Injection Analysis"
Tohoku J. Agric. Res. 1987 Volume 40, Issue NA Pages 169-172
Nakajima, H.;Kuno, T.

Abstract: NA

"Rapid Determination Of Cation Exchange Capacity In Farm Soil Using Flow Cell Method"
Tohoku J. Agric. Res. 1987 Volume 40, Issue NA Pages 173-NA
Takahashi, K.;Nakajima, H.

Abstract: NA

"Rapid Determination Of Different Forms Of Nitrogen In The Farm Soils By Cassette Flow Injection Analysis"
Tohoku J. Agric. Res. 1988 Volume 41, Issue NA Pages 173-174
Nakajima, H.;Saito, M.

Abstract: NA
Nitrogen Spectrophotometry Speciation

"Rapid Determination Of 10-3M H2SO4, NH4F HCl Extraction Forms Of Phosphate In The Farm Soils By Cassette Flow Injection Analysis"
Tohoku J. Agric. Res. 1988 Volume 41, Issue NA Pages 175-176
Nakajima, H.;Nira, R.

Abstract: NA
Phosphate Sample preparation

"Strategies For The Rapid Characterization Of Metals And Organic Pollutants In Solid Wastes And Contaminated Soils By Using Mass Spectrometry"
Trends Anal. Chem. 1998 Volume 17, Issue 5 Pages 263-272
Miguel de la Guardia and Salvador Garrigues

Abstract: Hyphenated techniques involving mass spectrometry (MS) such as ICP-MS, GC-MS and LC-MS are the most powerful tools for both qualitative and quantitative characterization of metals and organic pollutants in previously dissolved or extracted samples. However a considerable analytical effort is required in developing simple and general sample preparation strategies for the complete characterization of toxic substances in solid wastes and soils. This article gives a critical review, with 44 references, of the state-of-the-art and future perspectives for rapid procedures to evaluate the pollution of soils and sediments, also considering new alternatives like flow injection anal.-MS and direct sampling MS.
Metals Organic compounds Mass spectrometry Reverse Speciation Optimization

"On The Modernization Of Soil And Plant Chemical Analysis"
Turang Tongbao 1979 Volume 2, Issue 1 Pages 34-37
Fang Zhaolun

Abstract: Over the last decade, space science, environmental science and the increasingly popular computer applications for advances in modern analytical chemistry provided the impetus and conditions. Many of the original cumbersome chemical analysis operations in not too long a time realization of instrumentation, operation greatly simplified, computer applications not only analyze the operation and control of more automated equipment, but also in the handling, storage, retrieval analysis of data greatly improves work efficiency and some trace and ultra-trace elements analytical detection limit in the years to reduce the hundreds, thousands or even hundreds of times. former takes several days to complete the analysis of the project, now only takes a few minutes or even tens of seconds to complete the analysis. enable people to get rid of modern analytical chemistry a lot of ground cumbersome manual operation, greatly improved work efficiency, while improving the quality of data analysis to a level never reached. (Google Translate)

"Determination Of Total Phosphorus In Soil Digests By Flow Injection Analysis"
Turang Tongbao 1982 Volume 1982, Issue 4 Pages 40-42
Fang Zhaolun, Sun Lijing, Gao Zhan, Zhu Yan, Wang Xiuling, Li Lin

Abstract: In the early development of flow injection analysis, Ruzicka and other plants will soon successfully applied phosphorus molybdenum blue colorimetric assay, and in ensuring the accuracy of the analysis of 420 samples while achieving the highest / hour speed of analysis, but the Law reagent consumption is large. later after further improved significantly reduce reagent consumption. soil total phosphorus flow injection analysis has so far been reported. we build soil flow injection analysis of total phosphorus since 1977 work, repeatedly improved experimental device, choose the reagents and experimental conditions, the establishment of a method described in this article, after long trial, the effect is satisfactory. (Google translate)
Phosphorus Sample preparation Spectrophotometry

"Determination Of Total Nitrogen In Soil Digests By Flow Injection Analysis"
Turang Tongbao 1981 Volume 1981, Issue 5 Pages 38-39
Sun Lijing, Gao Zhanlin, Fang Zhaolun

Abstract: Flow Injection Analysis (referred to as FIA) is a continuous flow of rapid analytical techniques in recent years, it has a device is simple, easy operation, fast analysis, samples need less, etc., thus providing for the routine determination of large quantities of a more excellent way. Early in the flow injection analysis appears already applied to the determination of nitrogen in plants, but the determination of total nitrogen in soil has not been reported. (Google trasnlate)
Nitrogen, total Sample preparation Spectrophotometry

"Determination Of Soil Available Boron With Azomethine-H By Flow Injection Spectrophotometric Method"
Turang Tongbao 1983 Volume 1983, Issue 5 Pages 41-43
Sun, Lijing; Li, Lin; Fang, Zhaolun; Sun, Zheping

Abstract: Soil samples were treated with water, boiled for 30 min, filtered, and analyzed by flow injection analysis for boron. Filtrates were mixed with (NH4)2HPO4 buffer containing disodium EDTA, mixed with an aqueous solution containing azomethine-H [32266-60-7] and ascorbic acid, reacted for 48 s, then analyzed at 415 nm. Plots of boron concentrations and absorbance were linear in the range 0-5.5 ppm, and the detection limit was 0.02 ppm. Recoveries were 98-100.5%. Sixty samples could be analyzed per h, and results were satisfactory.
Boron Spectrophotometry

"Discussion On Modernization Of Soil And Plant Analysis"
Turang Tongbao 1984 Volume 15, Issue 5 Pages 230-232
Fang Zhaolun

Abstract: A review about applications of flow injection analysis and atomic absorption spectrometry in analysis of plant and soil samples with emphasis on trace elemental analysis.
Trace elements Spectrophotometry Review

"Determination Of Total Nitrogen In Soil Digests By Gas Diffusion Flow Injection Analysis"
Turang Tongbao 1986 Volume 1986, Issue 1 Pages 37-38
Sun Lijing, Li Lin, Fang Zhaolun

Abstract: For quantitation of total nitrogen in soil, the sample was treated with a catalytic mixture containing K2SO4, CuSO4, Se, and H2SO4 to convert the nitrogen into NH4+. The solution was then subjected to flow injection analysis in an alkaline solution. The NH4+ was converted into NH3(g) by the alkali and diffused through a PTFE membrane into an indicator solution containing cresol red (0.02), bromothymol blue (0.04), and bromocresol purple (0.08 g/100 mL). Upon reaction with NH3, the indicator solution underwent a color change that was detectable at 590 nm.
Nitrogen, total Sample preparation Gas diffusion Teflon membrane

"Effect Of Soil Acidity On The Determination Of Available Phosphorus In Soil With Continuous-flow Analyser"
Turang 1987 Volume 19, Issue 6 Pages 324-327
Li, Aihua

Abstract: The acidity of soil samples affected the determination of phosphorus with a continuous-flow automated analyzer. It is recommended that the sample solution should contain 0.083N H2SO4.

"Effect Of Nitrogen Application Timing On N Uptake By Vitis Labrusca In A Short-Season Region"
Am. J. Enol. Vitic. 2004 Volume 55, Issue 3 Pages 246-252
Randall J. Vos, Thomas J. Zabadal, and Eric J. Hanson

Abstract: Fertilizer nitrogen (N) was applied to Vitis labrusca L. cvs. Niagara and Concord grapevines in Michigan at various times to determine its effect on soil N levels and fertilizer N recovery in vine tissues. Labeled ammonium nitrate (15NH415NO3) was applied to the soil beneath vines at a rate of 68 kg N/ha at different times between budbreak and six weeks after bloom. Soil was sampled at one-to two-week intervals after the fertilizer applications to follow the inorganic soil N dynamics. Vines were excavated at the time of commercial grape harvest to quantify fertilizer N recovery. All times of fertilizer application resulted in less than 20% uptake of the N applied. Vines fertilized at budbreak generally contained less fertilizer N and allocated a greater fraction of the fertilizer N to fruit and leaves than later times of application. Vines fertilized later in the season absorbed more fertilizer N and allocated more of it and total N to the roots than earlier times of application. Later applications resulted in more fertilizer N remaining in the top 90 cm of soil at the end of the season. Based on these findings, N application to vineyards in this short-season region was more efficient between bloom and six weeks after bloom than at budbreak.
Nitrogen Ammonium, nitrogen Timed injection

"Multisyringe Flow Injection Analysis Of Stable And Radioactive Strontium In Samples Of Environmental Interest"
Appl. Radiat. Isot. 2004 Volume 61, Issue 2-3 Pages 273-277
Y. Fajardo, E. G&oacute;mez, F. Mas, F. Garcias, V. Cerd&agrave; and M. Casas

Abstract: A multisyringe flow injection (MSFIA) method for the determination of stable and radioactive strontium, using a solid phase resin (Sr-Resin), has been developed. Strontium concentrations are determined by atomic emission spectroscopy and by a low background proportional counter. The method has been applied to different samples (water, milk and soil) of environmental interest. The LLD of the stable and radioactive Sr were 10 µg/L and 0.01 Bq, respectively. The standard deviation of the separation procedure is 2% (n=10).
Strontium Strontium-90 Radiochemical Scintillation counter Spectrophotometry Multisyringe Speciation

"A Microplate Assay To Measure Soil Microbial Biomass Phosphorus"
Biol. Fert. Soils 2004 Volume 40, Issue 3 Pages 201-205
Richard Jeannotte, David W. Sommerville, Chantal Hamel, and Joann K. Whalen

Abstract: Quantification of phosphorus (P) concentrations in microbial biomass is required to better understand how P immobilization and turnover in soils are controlled by environmental and anthropogenic factors. Soil microbial biomass P (MBP) is generally extracted using the chloroform fumigation-direct extraction procedure and then analyzed for P using the ammonium molybdate-ascorbic acid method on a flow injection analysis (FIA) system. Our objective was to determine whether a microscale malachite green method on a microplate system would provide as accurate MBP analysis as the ascorbic acid method on an FIA system. Twelve soils were collected from agricultural fields in southwestern Quebec, fumigated with chloroform and extracted with 0.5 M NaHCO3 (pH 8.5). The dissolved inorganic phosphorus (DIP) concentration in fumigated soils was not affected by the method of analysis, and results from the two systems of analysis were significantly correlated (r =0.998, P <0.05). The MBP concentrations in these agricultural soils were between 0.36 and 60.05 µg P g-1, consistent with other published values. Our results indicate that MBP can be assessed equally well with the malachite green method using a microplate system as with the ascorbic acid method on an FIA system. The microplate system is rapid and requires smaller volumes of samples and reagents than the FIA system, thus reducing the quantity of waste produced. We conclude that the microscale malachite green method could be applied to measure the MBP concentration in a wide range of soils with good sensitivity, reproducibility and accuracy.
Phosphorus Spectrophotometry Method comparison

"Sequential Injection 90Sr Determination In Environmental Samples Using A Wetting-Film Extraction Method"
Anal. Chem. 2002 Volume 74, Issue 4 Pages 826-833
Manuel Mir&oacute;, Enrique G&oacute;mez, Jos&eacute; Manuel Estela, Montserrat Casas, and V&iacute;ctor Cerd&agrave;*

Abstract: A sequential injection procedure involving a flow-reversal wetting-film extraction method for the determination of the radionuclide 90Sr has been developed. The methodology is based on the coating of the inner walls of an open tubular reactor with a film prepared from a 0.14 M 4,4'(5')-bis(tert-butylcyclohexano)-18-crown-6 (BCHC) solution in 1-octanol, which allows the selective isolation of strontium from the sample matrix. Selection of the optimum extractant diluent attending its physical properties, investigation of the extraction kinetics features, and choice of the proper elution procedure are discussed in detail in this paper. The noteworthy aspects of using a wetting-film phase instead of a solid-phase material described to date in the literature are the reduction of crown ether consumption and the simplification of both the operational sequence and the automation of the extractant-phase renewal between consecutive samples, which is of interest to avoid analyte carryover and reduction of the resin capacity factor caused by irreversible interferences. The proposed method has been successfully applied to different spiked environmental samples (water, milk, and soil), with 90Sr total activities ranging between 0.07 and 0.30 Bq, measured using a low-background proportional counter. The standard deviation of the automated analytical separation procedure is lower than 3% (n = 10), and the 90Sr isolation process under the studied conditions may be carried out with a yield up to 80%.
Strontium-90 Radiochemical Scintillation counter Sequential injection Extraction Interferences

"Determination Of Trace Mercury In Soil By Atomic Fluorescence Spectrometry Combined With Mercury Vapor Reduction And Flow Injection On-line Extraction Technique"
Yejin Fenxi 2002 Volume 22, Issue 4 Pages 10-12
Liu Handong, Qiu Haiou, Cheng Cangcang, Wu Shaowei, Chen Hengchu, Tang Zhiyong, Jin Zexiang

Abstract: The FIA online non-aqueous extraction of mercury vapor reduction-AFS in soil samples of trace amounts of mercury in new Methods. Extraction of mercury [+ HNO3 + KI (NH2) 2CS] / TBP organic phase. NaBH4 soluble N, N-dimethylformamide (DMF), will be non-aqueous medium mercury produced by the reduction of mercury vapor into quartz heaters, for atomic fluorescence. The detection limit (K = 3) 0.05, RSD 5.2%. Using the method to determine the standards for soil samples of trace mercury, the results have been satisfactory.
Mercury Fluorescence Extraction Reference material