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
Email: schalk@unf.edu
Website: @unf

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Nitrate

  • IUPAC Name: nitrate
  • Molecular Formula: NO3-
  • CAS Registry Number: 14797-55-8
  • InChI: InChI=1S/NO3/c2-1(3)4/q-1
  • InChI Key: NHNBFGGVMKEFGY-UHFFFAOYSA-N

@ ChemSpider@ NIST@ PubChem

Citations 180

"Determination Of Traces Of Nitrite And Nitrate In Water By Solid Phase Spectrophotometry"
Anal. Chim. Acta 2000 Volume 410, Issue 1-2 Pages 185-192
M. N. Abbas and G. A. Mostafa

Abstract: A simple and sensitive method for the determination of nitrite and nitrate in water using solid phase spectrophotometry is described. The method utilizes the quantitative and rapid sorption of the dye formed from nitrite, using the Griess reaction, into a thin layer of polyurethane foam (PUF) where a pre-concentration factor of >140 has been achieved. Nitrate is pre-reduced using a cadmium reductor before applying the Griess reaction. The direct spectrophotometric measurement of the dye enriched in the solid foam phase has allowed the detection of as little as 5 and 40 ng mL-1 nitrite and nitrate, respectively. Optimization of the parameters affecting the quantitative formation and sorption of the dye into PUF has been considered. Analysis of natural water samples has been performed.
River Water Spectrophotometry Polyurethane foam Preconcentration Extraction Solid phase detection

"Simultaneous Determination Of Nitrite And Nitrate In Various Samples Using Flow Injection With Spectrophotometric Detection"
Anal. Chim. Acta 1999 Volume 382, Issue 1-2 Pages 15-21
Ali A. Ensafi and A. Kazemzadeh

Abstract: A direct spectrophotometric method for the simultaneous determination of nitrite and nitrate by flow injection analysis has been developed. The method is based on catalytic effect of nitrite on the oxidation of gallocyanine by bromate in acidic media and the decrease in absorbance of the system at 530 nm. The injected sample is split into two segments. One of the streams was directly treated with the above reagents and passed to the sample how cell of the spectrophotometer. The decrease in absorbance at 530 nm is due to the nitrite. The other stream was passed through a reductor minicolumn containing copperized-cadmium, where reduction of nitrate to nitrite occurs, and then the sample was treated with the mixed reagents and was passed through the same cell of the spectrophotometer. The total nitrite concentration initially plus that produced was determined. The influences of reagent concentration and manifold parameters were studied. The effect of potential interfering ions was examined. Nitrite and nitrate can be determined for the range of 0.010-2.500 µg mL-1 and 0.020-3.500 µg mL-1, respectively. The sampling rate of analysis was 20±3 hr-1, with 3s detection limits of 0.001 and 0.002 µg mL-1 for nitrite and nitrate, respectively. Nitrite and nitrate were determined in food and water samples by the proposed method with satisfactory results.
Food Environmental Spectrophotometry Catalysis Indirect Reduction column Simultaneous analysis Optimization Interferences

"A Flow System Exploiting Multicommutation For Speciation Of Inorganic Nitrogen In Waters"
Anal. Chim. Acta 2000 Volume 409, Issue 1-2 Pages 227-235
Fábio R. P. Rocha and Boaventura F. Reis

Abstract: A flow system for the speciation of inorganic nitrogen in waters is described. Multicommutation and binary sampling approaches are exploited to perform the sequential determination of nitrate, nitrite and ammonium without changing the manifold. Gravitational flow of solutions is employed in the sampling steps in order to avoid the effect of pulsation of the peristaltic pump on precision. A homemade photometer based on a dual-color (red/green) LED and a photodiode is employed to detect the reaction products. The repeatability was estimated as 0.32, 0.42 and 0.72% for nitrite, nitrate, and ammonium, respectively. A sampling rate of 60 determinations per hour was attained and the reagent consumption was reduced to 25% (ammonium) and 45% (nitrate and nitrite) relatively to conventional flow injection analysis (FIA) procedures. Detection limits of 5 µg L-1 NO2-, 15 µg L-1 NO3-, and 25 µg L-1 NH4+ were estimated at the 99.7% confidence level. Results for river water samples agreed with those obtained by conventional FIA or ion chromatography at the 95% confidence level.
River Spectrophotometry Multicommutation Speciation Photodiode Method comparison

"An Improved Technique For The Determination Of Oxidised Nitrogen In Natural Waters With A Sequential Injection Analysis (SIA) System"
Water SA 2001 Volume 27, Issue 3 Pages 355-360
EB Naidoo and JF van Staden

Abstract: An SIA systems proposed for the determination of oxidized nitrogen (nitrate + nitrite as N) in natural waters. A cadmium reductor, made of cadmium granules, closely packed in a glass column reduces the nitrate to nitrite. The reduced nitrate and the nitrite present in the water samples is diazotised in the SIA system with sulphanilamide and coupled with N - (1-napthyl) ethylene diammoniumdichloride to form a highly colored azo dye which is detected at 540 nm with a UV/Vis spectrophotometer. The proposed system is fully computerised and is able to monitor total oxidized nitrogen as nitrite at a frequency of 36 samples per hour with a standard deviation of < 1.2%, The calibration curve is linear up to 5 mg/l with a detection limit of 0.01 mg/l.
Environmental Spectrophotometry Column Solid phase reagent Automation

"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.
Blood Serum Environmental Clinical analysis Electrode Electrode Electrode Sample preparation Flowcell Apparatus Dual detection

"Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate By Flow Injection Analysis"
Anal. Chim. Acta 1979 Volume 110, Issue 1 Pages 123-128
Leif Anderson

Abstract: The flow injection principle is used in the photometric determination of nitrite and nitrate with sulfanilamide and N-(1-naphthyl)ethylenediamine as reagents. An on-line Cu-coated Cd reductor reduces nitrate to nitrite. The detection limit is 0.05 µM for nitrite and 0.1 µM for nitrate at a total sample volume of 200 µL. Thirty samples can be analyzed/h with a relative precision of ~1%.
Sea Spectrophotometry Suspended particulate matter Reduction column

"A Computer Controlled Multichannel Continuous-flow Analysis System Applied To The Measurement Of Nitrate, Chloride And Ammonium Ions In Small Samples Of Rain Water"
Anal. Chim. Acta 1980 Volume 113, Issue 2 Pages 331-342
J. Slanina, F. Bakker, A. Bruyn-Hes and J. J. M&ouml;ls

Abstract: A multichannel continuous flow system based on spectrophotometric determinations is described. Samples are injected into a water stream which is then mixed with appropriate reagents by merging flows; this mode improves the background signals. The system is controlled by a PDP 11 computer. Calibration, analysis of samples and quality control are done automatically. The system is applied to the determination of nitrate, chloride and ammonium ions in small ( 0.5 ml) samples of rain water in the range 0.2-20 ppm. The accuracy is typically better than 3%. The sampling rate is 18-35 per hour.
Rain Spectrophotometry Computer Multichannel

"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.
Environmental Water Spectrophotometry Reduction column Merging zones Multielement Proportional injector

"Flow Injection Analysis. Principles, Applications And Trends"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 19-44
J. Rika and Elo H. Hansen

Abstract: The basic principles of Flow Injection Analysis are outlined. The parameters governing the dispersion of the injected sample zone in the system are discussed, and it is demonstrated how these parameters can be manipulated in order to suit the requirements of an individual analytical procedure. A number of examples illustrating the practical application of f.i.a. are described, comprising the use of automated, stopped-flow, merging-zones, extraction techniques as well as f.i.a. scanning and methods based on intermittent pumping. Updated lists on f.i.a. procedures published and species that can be determined by f.i.a. are included.
Sample preparation Dispersion Extraction Merging zones Review Intermittent pumping Stopped-flow

"Utilization Of Flow Injection With Hydrazine Reduction And Photometric Detection For The Determination Of Nitrate In Rain-water"
Anal. Chim. Acta 1981 Volume 124, Issue 2 Pages 437-441
B. C. Madsen

Abstract: The hydrazine reduction method for determination of nitrate at the parts per million level is adapted to flow injection sample processing of rain-water. Reagent composition and physical variables were evaluated and optimized. Forty samples per hour can be processed. A precision of better than 3% is possible in the range of 1.0-10.0 ppm nitrate. Results for nitrate obtained from 9 rain-water samples agreed favorably with those determined by ion chromatography.
Rain Spectrophotometry

"Fast Determination Of Anions By Computerized Ion Chromatography Coupled With Selective Detectors"
Anal. Chim. Acta 1981 Volume 130, Issue 1 Pages 1-8
J. Slanina, F. P. Bakker, P. A. C. Jongejan, L. Van Lamoen and J. J. M&ouml;ls

Abstract: Up to 18 samples per hour can be analyzed for chloride, nitrate and sulfate by ion chromatography if the columns are thermostated (at ~40°C) and dead volume is minimized by the use of very small suppressor columns and minimal tubing. Accurate results are obtained from simple samples such as rain-water but nitrite, phosphate and bromide can interfere. These interferences can be avoided by the use of multiple detectors, such as a u.v. monitor at 220 nm and ion-selective electrodes (for fluoride and bromide). For samples containing more than 0.5 ppm of the ions of interest, a sample loop is used directly; the accuracy is typically 2-5%. For lower concentrations, a concentrator column is used with sample volumes up to 4 ml; this results in detection limits of 1-6 ppb for bromide, chloride, nitrate and sulfate. The computerized system is capable of analyzing large series of samples unattended.
Rain HPIC Electrode Computer

"Automated Simultaneous Determination Of Nitrate And Nitrite By Pre-valve Reduction Of Nitrate In A Flow Injection System"
Anal. Chim. Acta 1982 Volume 138, Issue 1 Pages 403-408
Jacobus F. Van Staden

Abstract: Nitrate is reduced to nitrite by using the pre-valve in-valve reduction technique prior to the sampling system. One loop of a two-position sampling valve is replaced by a copperised cadmium column. Nitrite from the samples as well as nitrite formed in the reduction procedure is sampled by a second valve and introduced into the flow system. The two sampling valves are synchronised in such a way that two peaks are obtained, one corresponding to the nitrate plus nitrite and the other to the nitrite only. The method is suitable for the simultaneous determination of nitrate and nitrite at a sampling rate of up to 72 determinations per hour with coefficients of variation better than 1.96% for nitrate and 0.83% for nitrite.
Environmental Spectrophotometry Sample valve manipulation Simultaneous analysis

"The Application Of Strongly Reducing Agents In Flow Injection Analysis. 1. Chromium(II) And Vanadium(II)"
Anal. Chim. Acta 1983 Volume 145, Issue 1 Pages 197-201
R. C. Schotohrst, J. M. Reijn, H. Poppe and G. Den Boef

Abstract: Many reagenst cannot easily be applied in quantitative analysis, because of their instability under atmospheric conditions. When such reagents are prepared in a flowing stream, their applicability is very promising; for example, in flow injection analysis, a reagent need be stable only for 20-30 s. The application of chromium(II) and vanadium(II) in flow injection analysis is described. Nitrate and nitrile can be determined in the concentration range 5 x 10^-5-5 x 10^-3. Calibration graphs show good linearity.
Spectrophotometry

"A Simple Procedure For Standard Additions In Flow Injection Analysis. Spectrophotometric Determination Of Nitrate In Plant Extracts"
Anal. Chim. Acta 1983 Volume 155, Issue 1 Pages 131-138
M. F. Gin&eacute;, B. F. Reis, E. A. G. Zaatto, F. J. Krug and A. O. Jacintho

Abstract: A standard solution of NO3- is injected into water as carrier, creating a zone that undergoes continuous dispersion as it is carried through a coil. After a pre-selected time interval, Δt, a segment of the dispersed zone is introduced into a second water carrier stream and, simultaneously, the sample is injected into its carrier stream. The two established zones merge and undergo all the required physico-chemical steps before reaching the detector. The amount of standard added is determined by the value of Δt, so that several standard additions can be made by varying Δt. Application of the method is illustrated by the spectrophotometric determination of NO3- in extracts of plant leaves. Results on seven samples (12 additions per sample) agreed well with those by the corresponding manual procedure.
Plant Sample preparation Spectrophotometry Apparatus Injector Merging zones Standard additions calibration

"The Application Of Strongly Reducing Agents In Flow Injection Analysis. 4. Uranium(III)"
Anal. Chim. Acta 1984 Volume 162, Issue 1 Pages 1-8
R. C. Schothorst, M. Van Son and G. Den Boef

Abstract: Tervalent U, in HCl medium, has been used as a reducing agent in the flow injection system previously described (cf. Part II, Anal. Abstr., 1984, 46, 5A6) for the determination of various inorganic and organic species. Detection was by spectrophotometry at 350 nm or by amperometry at -0.91 V vs. the SCE The limit of determination by spectrophotometric detection was ~10 µM; for NO3- and NO2-, the limits were similar by both modes of detection. The method was more sensitive than that involving use of Cr(II) or V(II) as reducing agent (loc. cit.). (For Part III see Anal. Abstr., 1985, 47, 5A13).
Amperometry Spectrophotometry

"Flow-through Tubular PVC Matrix Membrane Electrode Without Inner Reference Solution For Flow Injection Analysis"
Anal. Chim. Acta 1984 Volume 164, Issue 1 Pages 147-152
S. Alegret, J. Alonso, J. Bartrol&iacute; and J. M. Paul&iacute;s, J. L. F. C. Lima and A. A. S. C. Machado

Abstract: The construction is described (with diagrams) of a tubular NO3--selective electrode that is based on a mobile carrier cemented in a PVC matrix, and in which a conductive epoxy-resin (with a silver base) is used as a solid inner contact in place of the inner reference solution Graphs are presented that show the effects of varying the injection volume, flow rate and tubing length on the dispersion. The upper and lower limits of near-Nernstian response vary with dispersion, and, under optimum conditions, these limits are 0.1 M and 80 µM. By use of flow lines with little dispersion, rapid (7.4 s) responses can be obtained for 10 µM-NO3-, thus permitting sampling rates of 120 h-1. For 100 µL injections of 0.1 mM , 1 mM and 10 mM NO3-, the coefficient of variation were 0.1, 0.56 and 0.44%, respectively (n = 10). The sensor membrane had a lifetime of ~1 month.
Electrode Electrode Electrode Electrode Dispersion

"Applications Of Ion-exchange Minicolumns In A Flow Injection System For The Spectrophotometric Determination Of Anions"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 233-244
Azad T. Faizullah and Alan Townshend

Abstract: The flow injection method is based on the displacement of SCN- bound to Dowex 1-X4 (200 mesh) by SO42-, Cl- and NO3-. The SCN- is treated with Fe(III) and the absorbance of the Fe - SCN- complex formed is measured at 465 nm. For the determination of NO3- in the presence of SO42- and Cl-, the SO42- and Cl- can be removed by use of a pre-column containing Dowex 50-X8 (Ag+ form) and a Jones zinc reductor (1.5 cm x 2 mm). Binary mixtures, e.g., Cl- and NO3-, can be analyzed by splitting the sample in the flow stream so that a part goes through the suppressor and another by-passes it to give a total response. The coefficient of variation for 0.11 mM NO3- is 1.5% (n = 5). The method is applied to the determination of NO3- in tap-water.
Water Ion exchange Spectrophotometry Interferences Resin

"Sequential Atomic Absorption Spectrometric Determination Of Nitrate And Nitrite In Meats By Liquid - Liquid Extraction In A Flow Injection System"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 341-349
M. Silva, M. Gallego and M. Valc&aacute;rcel

Abstract: The method is based on the reaction of NO3- with a Cu(I) - neocuproine (1:2) complex to form an ion pair that is extracted into isobutyl methyl ketone. The displaced Cu in the extract is determined in the flow injection system by AAS detection. For separation of NO3- and NO2-, the latter is oxidized to NO3- with Ce(SO4)2 and the total NO3- is determined. Separately, the NO2- is decomposed with sulfamic acid and the NO3- alone is measured; NO2- can then be determined by the difference. The method is applicable to NO3--to-NO2- ratios in the range from 10:1 to 1:10. The coefficient of variation (n = 11) for a mixture containing 0.7 µg of each ion is 3.7 and 4.1% for NO3- and NO2-, respectively. Recoveries from meat and meat products range from 95 to 102.8% with coefficient of variation (n = 15) of ~1.9% for both ions. Serious interference from Cl- can be eliminated.
Meat Spectrophotometry Sample preparation Extraction Interferences Simultaneous analysis

"Spectrophotometric Flow Injection Determination Of Nitrate Based On Reduction With Titanium(III) Chloride"
Anal. Chim. Acta 1986 Volume 186, Issue 1 Pages 289-294
A. Al-Wehaid and Alan Townshend

Abstract: The test solution (containing 0.02 to 5 µg mL-1 of N) is injected into a stream of water, which is then mixed with a stream of aqueous 6% TiCl3; the resulting NO2- then reacts in a stream of 0.6 M HCl containing 2% of sulfanilamide and 0.05% of N-1-naphthylethylenediamine dihydrochloride to form an azo-compound which is detected at 530 nm. Calibration graphs are rectilinear up to 5 µg mL-1 of N. The detection limit is 0.02 µg mL-1 of N. Interference from Cu(II) can be removed with use of Dowex 50W-X8 (H+ form) cation-exchange resin (other common ions do not interfere). The method is applied to potable water.
Water Spectrophotometry Interferences

"Fluorimetric Determination Of Nitrate In Natural Waters With 3-amino-1,5-naphthalenedisulfonic Acid In A Flow Injection System"
Anal. Chim. Acta 1987 Volume 193, Issue 1 Pages 343-347
Shoji Motomizu, Hiroshi Mikasa and Kyoji T&ocirc;ei

Abstract: The sample (160 µL) was injected into a carrier stream containing 1 mM EDTA, 50 mM NaCl and water (pH 8.1 to 8.4) and the solution was passed through a copperized cadmium column to reduce the NO3- to NO2-. The solution was then mixed with a stream containing 2 M HCl, 1 mM EDTA and 3-aminonaphthalene-1,5-disulfonic acid (0.3 mM or 30 µM) at 90°C. The azoic acid derivative produced was determined by mixing this stream with aqueous 20% NaOH and measuring the fluorescence at 470 nm (excitation at 365 nm). The flow rate of each stream was 0.7 mL min-1. Calibration graphs were rectilinear for up to 0.2 mM NO3-; the detection limit was ~1 nM-NO3-. In the determination of 20 µM-NO3-, the coefficient of variation was 0.8% (n = 10). Most cations and anions commonly found in natural waters did not interfere. Results for river and seawater samples agreed with those obtained by ion chromatography.
River Sea Fluorescence Interferences Column Heated reaction

"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.
Environmental Amperometry Electrode Electrode Electrode Electrode Sample preparation Potentiometry Interferences Method comparison

"Automated Spectrophotometric Field Monitor For Water Quality Parameters. Determination Of Nitrate"
Anal. Chim. Acta 1987 Volume 200, Issue 1 Pages 523-531
J. Richard Clinch and Paul J. Worsfold, Harry Casey

Abstract: The design and operation are described of an automated spectrophotometric field monitor based on flow injection analysis for the determination of NO3- in river water. The sample (30 µL) is injected into aqueous 1% NH4Cl as carrier stream (0.7 mL min-1); the solution then passes through a 40-mm reductor column of copperized Cd, and is mixed with N-1-naphthylethylenediamine dihydrochloride (0.25 g l-1) - sulfanilamide (12.5 g l-1) solution in 10% H3PO4. The absorbance of the resulting solution is monitored by a photometric detector with a green light-emitting diode. Response was rectilinear up to 12 mg L-1 of nitrate-N and the detection limit was 24 µg l-1. The coefficient of variation ranged from 0.0 to 0.7%. Results agreed well with those from two other spectrophotometric methods.
River Spectrophotometry Light emitting diode Method comparison Reduction column Portable

"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.
Environmental Electrode Electrode Electrode Electrode Sample preparation Sensor Method comparison Simultaneous analysis

"Determination Of Nitrate By Flow Injection Analysis With An Online Anion-exchange Column"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 331-338
Surekha Devi and Alan Townshend

Abstract: Nitrate was determined by displacement of SCN- from an online anion-exchange mini-column and subsequent reaction with Fe(III) to give a red complex which was detected at 480 nm. Two suppressor columns were developed to remove anionic interference. A Pb2+-loaded ion-exchange column was used to allow determination of NO3- in the presence of SO42-, and a column loaded with Ag and Pb allowed determination of NO3- in the presence of SO42-, SO32- and Cl-. A copperized Cd reductor column was placed immediately after the suppressor column to trap eluted Ag and Pb ions which would otherwise depress NO3- response. The calibration graph was rectilinear for 50 to 600 µM-NO3-. The detection limit was 50 nM, and the coefficient of variation was 1%. The method was successfully applied to tap-water.
Water Ion exchange Interferences Reduction column

"Determination Of Nitrate With A Flow Injection System Combining Square-wave Polarographic Detection With Online Deaeration"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 475-478
Mouna Noufi, Ch. Yarnitzky and Magda Ariel

Abstract: The catalytic reaction between NO3- and UO22+ is used to provide a simple, rapid, sensitive and accurate method for determining NO3- in river and potable water. The carrier (H2O) and reagent (0.2 M KCl - 0.02 M HCl - 0.2 mM - UO22+) streams are pumped (0.6 mL min-1) into a coil (30 cm x 0.5 mm) and 200 µL of aqueous NO3- is injected. A diagram of the apparatus is given. Voltammetry is performed with reference to an Ag - AgCl (3 M KCl) electrode, delay 4 s, scan rate 100 mV s-1 and a potential range of -0.6 to -1.1 V. The calibration graph is rectilinear for 5 to 60 µM-NO3-1, with a detection limit of 2 µM. The effect of anions on the reduction is studied.
River Water Polarography Electrode Voltammetry Catalysis Apparatus Calibration Detection limit

"Photolithographically Patternable Nitrate-sensitive Acrylate-based Membrane"
Anal. Chim. Acta 1991 Volume 243, Issue 2 Pages 179-182
C. Dumschat, R. Fr&ouml;mer, H. Rautschek, H. M&uuml;ller and H. -J. Timpe

Abstract: A photocurable acrylate matrix nitrate-sensitive membrane containing 2-nitrophenyl n-octyl ether as mediator and tetraalkylammonium nitrate as an active compound is described. The photocuring was achieved by the use of photoinitiators containing diaryliodonium chloride. This acrylate membrane is patternable via a photolithographic process with a only slight loss of electrochemical characteristics.
Electrode Electrode Membrane

"Flow Injection Determination Of Inorganic Forms Of Nitrogen By Gas Diffusion And Conductimetry"
Anal. Chim. Acta 1991 Volume 245, Issue 2 Pages 183-190
Lourival Cardoso de Faria and Celio Pasquini

Abstract: A flow injection conductimetric method was applied to the determination of ammonia, nitrate and nitrite at concentrations down to 5, 20 and 20 ng mL-1, respectively. Ammonia was determined by merging the injected sample with an alkaline solution (NaOH-EDTA) and passing the mixture through a diffusion cell. The ammonia released was collected by a flowing stream of deionized water that passed through a conductance flow cell. Nitrate and nitrite concentrations were determined after reduction to ammonia in alkaline medium using a column filled with metallic zinc. The ammonia produced was then measured as described above. About 60 samples per hour can be processed with a relative standard deviation of about 1%. Satisfactory agreement was observed between results for ammonia in samples of natural water and nitrate in tap and mineral water determined by the proposed method and by standard spectrophotometric procedures. Speciation can be achieved by adding sulfanilic acid to remove nitrite from the sample and determining the ammonia without the use of the column.
Water Mineral Conductometry Gas diffusion Speciation

"Simultaneous Determination Of Nitrite And Nitrate In Water Using Flow Injection Biamperometry"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 391-398
Marek Trojanowicz*, Wojciech Matuszewski and Bogdan Szostek, Jacek Michaowski

Abstract: The sample is injected into a carrier stream of aqueous 0.2% NH4Cl, which is split into two streams; one passes through a 30-cm tube and is then merged with the second stream, which flows through a column (6 cm x 2 mm) of Cd powder (0.1 to 1.5 mm) as reducing agent and a delay coil. The combined stream is mixed with 0.1 M KI - 0.125 M H2SO4 before reaching a detector equipped with two Pt electrodes polarized at 100 mV, where NO2- is detected by means of the I2 - I- redox system (Hulanicki et al., Ibid., 1987, 194, 119). The first peak obtained corresponds to NO2- and the second to NO3- plus NO2-. Under optimized conditions (described), the coefficient of variation for 60 µM-NO2- was 1.4 to 2.2% and that for 60 µM-NO2- and 0.4 mM NO3- was 0.5 to 0.8%. The max. sampling rate was 15 h-1. Copper (3 mg l-1) could be masked with EDTA, >1 mg L-1 of residual Cl had to be removed initially on a charcoal column, Fe(III) could be masked by adding oxalate to the sample before injection, and Cr(VI), which interfered in the determination of NO2-, could be removed by anion exchange at pH 7.8. In the analysis of natural water, results were well correlated with those of ion-selective potentiometry. Detection with 2 polarized Pt wire electrodes is based on the oxidation of I- by NO2-. The current is proportional to the amt. of I formed. The injected sample is split in a flow injection manifold into 2 segments. One of them is transported through a reductor minicolumn containing copperized Cd, where reduction of NO3- to NO2- occurs. The effects of interfering species such as Cu(II), Fe(III), Cr(VI) and residual Cl were examined and procedures for their elimination are proposed. With a sampling rate of 15/h, detection limits of 40 and 70 µg/L were obtained for NO2- and NO3-, respectively.
Environmental Electrode Potentiometry Optimization Reduction column Interferences Method comparison

"Kinetic - Spectrofluorimetric Determination Of Nitrite And Nitrate At The Nanograms-per-millilitre Level By Manual And Flow Injection Methods"
Anal. Chim. Acta 1992 Volume 265, Issue 1 Pages 103-110
Tomas P&eacute;rez-Ruiz*, Carmen Martinez-Lozano and Virginia Tom&aacute;s

Abstract: To a mixture of 0.1 mM phenosafranine, 2 M H2SO4 and 0.02 M KBrO3 was added sample or NO2- standard solution After dilution with water, a portion of the reaction mixture was placed in a cell at 30°C and the fluorescence intensity (excitation 525 nm, emission 576 nm) was measured against time from 30 s after the addition of NO2-. The method was rectilinear in the range 0.9 to 13.8 ng mL-1 of NO2-, with a coefficient of variation of 1.5%. The method was adapted for flow injection analysis in the stopped-flow mode, using 140 µL samples and a 30 cm x 0.5 mm reactor. The calibration graph was rectilinear in the range 46 to 460 ng mL-1 and the detection limit was 27 ng mL-1 of NO2-. Inclusion of a copperized cadmium reductor column allowed the determination of NO3-; the calibration graph was rectilinear in the range 62 to 620 ng mL-1 and the coefficient of variation was 1.3% for 248 ng mL-1 of NO3- (n = 10). Addition of a selection valve permitted the simultaneous determination of NO2- and NO3-. Both the manual and flow injection methods were applied to the analysis of natural and waste waters and meat products. The catalytic effect of nitrite on the oxidation of phenosafranine by bromate in acidic medium was studied by using the decrease in fluorescence intensity of phenosafranine. This kinetic- spectrofluorimetric method for nitrite is linear over the range 0.9-13.8 ng mL-1 with a relative standard deviation of about 1.5%. The method can be successfully adapted to flow injection analysis in the stopped-flow mode. Manual and flow injection methods were satisfactorily applied to the determination of nitrite in water and meat products. The inclusion of a copperized cadmium column in the flow system allowed the determination of nitrate and the sequential determination of nitrate and nitrite in mixtures.
Environmental Meat Fluorescence Kinetic Catalysis Stopped-flow Reduction column

"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.
Environmental Sample preparation Spectrophotometry Apparatus Optimization Heated reaction

"Simultaneous Determination Of Nitrate And Chloride By Means Of Flow Injection Amperometry At The Membrane-stabilized Water - Nitrobenzene Interface"
Anal. Chim. Acta 1992 Volume 268, Issue 2 Pages 285-292
Stefan Wilke*, Halka Franzke and Helmut M&uuml;ller

Abstract: Sample solution (16 µL) was injected into a carrier stream of water which merged with a supporting electrolyte of aqueous 10 mM Na2SO4; the flow rate of each stream was 1 mL min-1. The flow-through electrochemical detector cell (illustrated) contained a hydrophilic membrane filter of regenerated celullose (RC 58, Schleicher and Schuell) to stabilize the interface between the aqueous solution and an organic phase of 10 mM µ-nitridobis(triphenylphosphorus) dicarbollylcobaltate in nitrobenzene. Two Ag wires in the organic phase were used as reference and auxiliary electrodes while in the aqueous phase a Ag - AgCl electrode and the stainless-steel cell body were used. The electrodes were connected to a potentiostat (cf. Wilke, J. Electroanal. Chem., 1991, 301, 67), the filtered output from which was recorded. The results obtained for NO3- agreed well with those obtained by ion chromatography. The detector was ~11 times more sensitive to NO3- than to Cl-, and measurements of Cl- were thus only possible at high concentration. The technique was used to determine NO3- and Cl- in river water. An amperometric flow-through electrode based on ion transfer across the interface of 2 immiscible electrolyte solutions was developed. A hydrophilic cellulose membrane was utilized to stabilize the interface between the flowing aqueous solution and the stationary organic phase. The detector developed was applied in a flow injection system for the simultaneous determination of NO3- and Cl- in river water. Advantage was taken of the potential-dependent response of the amperometric detector and the sufficiently separated half-wave potentials of the transfer of NO3- and Cl- across the interface. The results obtained in the amperometric determination of NO3- agreed well with those from ion chromatography measurements. Because of the comparatively poor selectivity of the detector for Cl-, the amperometric determination can be used only when the Cl- concentration. of the sample is sufficiently high.
River Amperometry Electrode Organic phase detection Detector Apparatus Interferences Hydrophilic membrane Cellulose

"Determination Of Nitrate In Natural Waters With The Photo-induced Conversion Of Nitrate To Nitrite"
Anal. Chim. Acta 1993 Volume 276, Issue 1 Pages 25-32
Kazuhiko Takeda and Kitao Fujiwara*

Abstract: A flow injection system with a UV irradiation coil cell, in which NO3- was reduced to NO2-, and a spectrophotometric detector is described (diagram given). The carrier solution was phosphate buffer or water and the reagent solution contained 1.9 mM N-1-naphthylethylenediamine, 29 mM sulfanilamide and 0.6 M HCl. It was propelled by plunger pump to a reaction coil. The absorbance was monitored at 540 nm by a UV spectrophotometer. Peak height of the absorbance was taken as the signal intensity, which depended strongly on the carrier solution pH. The calibration graph was rectilinear from 0.05 to 100 µM-nitrate in natural waters and the coefficient of variation at 10 µM was 3%. Up to 10 samples h-1 could be analyzed.
Environmental Spectrophotometry Photochemistry Redox

"Inter-laboratory Programme For The Quality Control Of Nitrate Determination In Fresh Water"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 600-606
Ph. Quevauviller, D. Van Renterghem and B. Griepink, M. Valcarcel*, M. D. Luque De Castrol and J. Cosano

Abstract: Certified reference materials for this analysis were prepared that contained 0.8, 8 or 53.8 mg/l of nitrate and had a hardness of ~10 degrees (French). Boiled water was sterilized and homogenized and passed through sterilized filters before the addition of the nitrate plus CaCl2 (91.7 mg/l), MgSO4 (123 mg/l), Na2CO3 (530 mg/l), and potassium hydrogen phthalate (5 mg/l) to introduce K+ and additional organic matter to simulate the presence of humic acids. These materials were stored in white glass ampoules at +20°C and remained stable for at least 3 months. The reference materials were analyzed for nitrate by a flow injection method based on the Griess reaction. The sample was injected into a carrier solution of NH4Cl, Na2B4O7 and EDTA, which was passed through a column of copperized Cd to reduce nitrate to nitrite. The resulting solution was introduced into a stream of sulfanilamide solution and the absorbance of the resulting azo-compound was monitored at 540 nm. Experimental set-up variations in the collaborating laboratories are detailed. For the 0.8 mg/l solution, the inter-laboratory RSD was high (8.7%) possibly because the non-linearity of the calibration graph had been disregarded.
River Spectrophotometry Redox EDTA Reference material

"Flow Injection Analysis With Bulk Extraction Based Optical Sensor Membranes"
Anal. Chim. Acta 1994 Volume 294, Issue 1 Pages 49-56
Peter C. Hauser* and J. Christopher Litten

Abstract: A review is presented of some applications of optical sensing membranes as solid-phase photometric detectors in inorganic FIA. The membranes contain one or more selective ionophores or lipophilic pH indicators in a PVC matrix. Examples of test applications to determinations of Ca, K, Zn, ammonium and nitrate are described and commended as alternatives to flow injection potentiometry, with simpler operation and similar selectivities and detection limits. Light-emitting diode-photodiode transducer detectors were used. (28 references).
Industrial Electrode Spectrophotometry Potentiometry Sample preparation Sensor Review Photodiode Extraction

"Comparison Of The Analytical Capabilities Of An Amperometric And An Optical Sensor For The Determination Of Nitrate In River And Well Water"
Anal. Chim. Acta 1994 Volume 299, Issue 1 Pages 81-90
Margaret A. Stanley, Joe Maxwell, Mairead Forrestal, Andrew P. Doherty, Brian D. MacCraith, Dermot Diamond and Johannes G. Vos

Abstract: The analysis of nitrate in water has been studied using novel amperometric and optical sensors. A flow-injection analysis system with amperometric detection has been developed in which nitrate is determined as nitrite after reduction in a cadmium column. The working electrode is glassy carbon modified with a crosslinked redox polymer. The linear range is 0.1 to 190 mg/l NO3-N (r>>0.999) and the limit of detection (LOD) is 50 µg/l NO3-N. A fiber optic sensor based on a dual wavelength absorption approach has also been developed. A signal at 210 nm where nitrate absorbs was referenced against a signal at 275 nm where nitrate does not absorb. Its linear range is from 0.4 to 30 mg/l NO3-N and its LOD is 400 µg/l NO3-N. These diverse methods have been applied to the analysis of the same river water samples and good correlations have been observed between the two measurement techniques and a standard ion chromatography method.
River Well Amperometry Sensor Method comparison

"Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate In A Flow Injection System"
Anal. Chim. Acta 1995 Volume 302, Issue 2-3 Pages 283-287
Anatol Kojo* and Ewa Gorodkiewicz

Abstract: The FIA system incorporated a PTFE sample loop (50 cm x 1.5 mm i.d.) containing 29 cm of copperized Cd granules (<0.3 mm) through which the aqueous sample was introduced into 0.1 M NH4Cl as carrier. The resulting stream was merged with 60 mM sulfanilamide in 0.6 M HCl and then with 4 mM N-1-naphthylethylenediamine before passing to a flow cell for absorbance measurement at 510 nm. The reagent flow rate was 1.8 ml/min. As only part of the sample made contact with the reductant, the first portion of sample injected into the carrier stream contained nitrite and nitrate, whereas the second portion contained the original nitrite plus that from reduction of nitrate. The height of the shoulder on the recorded signal was proportional to nitrite and the maximum peak height was proportional to nitrite plus nitrate. Response was linear up to 35 and 10 mg/l of nitrate and nitrite, respectively, and at 4 and 1 mg/l, respectively, the corresponding RSD were 0.9 and 1.9%. The method showed good selectivity, and was applied to river water.
River Spectrophotometry Simultaneous analysis Dual reaction zones

"Simultaneous Flow Injection Determination Of Nitrate And Nitrite In Water By Gas-phase Chemiluminescence"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 308-312
Toyoaki Aoki* and Muneki Wakabayashi

Abstract: A flow injection procedure for the determination of nitrate (I) and nitrite (II) based on their reduction to NO followed by membrane phase separation and chemiluminescence detection was developed. Reductant was injected into a 0.5 M H2SO4 carrier stream (0.5 ml/min) which was merged with streams of sample solution (0.5 ml/min) and clean air (6 ml/min). After passing through a mixing coil (2 m x 1 mm i.d.), the mixture was propelled to the phase separator. The separator comprised an outer PTFE tube (4 mm i.d.) and an inner porous PTFE tube (2 mm i.d.). Air and NO permeated through the microporous membrane into a clean air stream and were swept to the chemiluminescent analyzer. (CL) where the chemiluminescence produced by with ozone was monitored. A Nafion permeation tube removed moisture. The reductant was 20% Ti(III) for the combined determination of I and II and 5% KI for the determination of II. The calibration graphs were linear for 5 µg N/l (I) and 3 µg N/l (II) to ~e;1 mg N/l. The detection limits were 0.7 ppb I and 0.35 ppb II. RSD (n = 5) were 1.2% for 0.7 ppm I and 1.4% for 0.28 ppm II. The method was used to determine I and II in river water and sewage effluent. The results agreed with those obtained by conventional methods (details given).
Effluent River Chemiluminescence Gas phase detection Method comparison Permeation tube Nafion membrane Teflon membrane Phase separator

"Characterization And Reduction Of Interferences In Flow Injection Analysis For The In Situ Determination Of Nitrate And Nitrite In Seawater"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 413-424
Anne Daniel, a, Dominique Birot*, Michel Lehaitre and Jacques Poncin

Abstract: An FIA method for the in situ determination of nitrate and nitrite in seawater was studied in order to improve the precision and sensitivity. The method was based on the reduction of nitrate to nitrite using a Cd column and the spectrophotometric detection of nitrite following reaction with an azo dye. The Cd reduction column could be switched in and out of the line to allow the determination of nitrite and total nitrate/nitrite concentrations. The sample stream (1.4 ml/min) was merged with a 30 g/l ammonium chloride buffer stream of pH 8.5. After passing through the reduction column, the flow was split into two equal streams of 1.2 ml/min each. These streams were merged with streams (0.6 ml/min) of 10 g/l sulfanilamide in 10% HCl or 1 g/l N-(1-naphthyl)ethylenediamine. The streams were recombined before passing through the reaction coil to the detection cell where the absorbance at 540 nm was measured against a background at 630 nm. The calibration graph was linear for up to 40 µM-nitrate and the detection limit was 0.45 µM. The RSD (n = 6) for the determination of 0.5 µM-nitrate were ~e;5%. The effects of pressure, salinity and temperature on the determination were studied.
Sea Spectrophotometry Interferences Reduction column Optimization Refractive index Sample splitting

"Photo-induced Reduction Of Nitrate To Nitrite And Its Application To The Sensitive Determination Of Nitrate In Natural Waters"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 406-412
Shoji Motomizu* and Masahiro Sanada

Abstract: An FIA method was described for the determination of nitrate in water based on the photo-induced reduction of nitrate to nitrite. Water (280 µL) was injected into a carrier stream (0.6 ml/min) containing 0.1 M KH2PO4 and 1 mM EDTA of pH 7. The flow passed to the photo-reactor which consisted of a PTFE tube (3 m x 0.8 mm i.d.) wound directly around a low-pressure Hg lamp (4 W). The flow from the photo-reactor was merged with the chromogenic reagent stream (0.6 ml/min) which contained 30 mM sulfanilamide and 2 mM N-(1-naphthyl)ethylendiamine in 0.6 M HCl. After passing through the reaction coil (2 m x 0.5 mm i.d.) the absorbance was measured at 540 nm. The calibration graph for nitrate was linear up to 0.1 mM, the detection limit was 0.03 µM and the RSD (n = 7) for the determination of 4 µM-nitrate was 0.8%.
Environmental Spectrophotometry Indirect Photochemistry Chromogenic reagent

"Application Of Photoacoustic Spectrometry To Flow Injection Analysis"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 20-27
I. Carrer, P. Cusmai, E. Zanzotter, W. Martinotti,* and F. Realini

Abstract: The cited method was used to determine nitrite, nitrate, Fe, NH3 and phosphate ions in water. Excitation was performed with a Q-switched Nd:YAG laser equipped with a 2nd harmonic generator for the determination of nitrite, nitrate and Fe at 532 nm. The same laser was used to pump the dye laser for the detection of NH3 at 632 nm and phosphate at 810 nm. The generated acoustic wave was detected by an acoustic transducer. The FIA manifold allowed the sample solution to be injected into a water carrier stream which was merged sequentially with two reagent streams (R1 and R2) before passing to the detector cell. For the determination of nitrite, R1 and R2 were NH3 buffer and α-naphthylethylenediamine dihydrochloride. The same reagents were used for the determination of nitrate by incorporating a copperized Cd reduction column to reduce nitrate to nitrite. R1 and R2 were hydroxylamine hydrochloride and 1,10-phenanthroline, respectively, for the determination of Fe and ammonium molybdate and antimony potassium tartrate, respectively, for the determination of orthophosphate. The Berthelot reaction was used for the detection of NH3. The detection limits (tabulated) were comparable with those obtained by FIA with spectrophotometric detection for Fe, NH3 and phosphate. For nitrite and nitrate poorer detection limits were obtained.
Environmental Spectrometry Sensor Laser Reduction column Method comparison

"Differential Flow Injection Potentiometry"
Anal. Chim. Acta 1995 Volume 311, Issue 2 Pages 175-181
Ivelin Rizov* and Liliana Ilcheva

Abstract: Flow injection potentiometric methods using two different ISE placed in series are described for the simultaneous determination of (i) nitrate and chloride and (ii) nitrate and ammonium. The flow injection manifold for the determination of nitrate and chloride consisted of a nitrate ISE separated from a chloride ISE by a reaction coil of 254 cm x 0.51 mm i.d. A sample volume of 60 µL was injected into a 0.04 M Na2SO4 carrier stream (6.3 ml/min). The nitrate concentration was determined using the chloride ISE as a reference electrode and vice versa. The RSD (n = 13) for the determination of 0.1 mM nitrate and 1 mM chloride were 1.1 and 0.9%, respectively. A similar manifold is described for the determination of nitrate and ammonium using nitrate and ammonium ISE separated by a reaction coil of 284 cm x 0.51 mm i.d. The RSD (n = 12) for the determination of nitrate and ammonium in waste water from a urea production plant were 1.1 and 0.9%, respectively.
Industrial Waste Electrode Electrode Electrode Potentiometry Dual detection

"Differential Flow Injection Potentiometry With Double Sensitivity Using One Ion-selective Membrane"
Anal. Chim. Acta 1995 Volume 313, Issue 1-2 Pages 83-87
Frank Zuther*, Bernd Ross and Karl Cammann

Abstract: Nitrate was determined by differential flow injection potentiometry using a symmetrical flow-through cell equipped with one ion-selective membrane and two Ag/AgCl reference electrodes, one positioned on each side of the membrane. The two sides of the detection cell were connected by a PTFE tube (0.8 mm i.d.) which allowed the sample to come into contact with both sides of the membrane. Separate or overlapping peaks could be obtained by varying the length of the connecting tube. The ion-selective membrane (10 x 5 mm) consisted of tetradodecylammonium bromide, potassium tetrakis(4-chlorophenyl)borate and 2-nitrophenyloctyl ether in a PVC matrix. The carrier solution (3 ml/min) was 1 mM Li2SO4. The calibration graph for up to 10 mM nitrate showed a sensitivity of 115.2±1.2 mV/decade when using a connecting tube volume of 2 mL and an injection volume of 1 mL. A sensitivity of 110.5±0.8 mV/decade was obtained for the same calibration range with a connecting tube volume of 0.25 mL and an injection volume of 0.5 mL. A detection limit of 0.6 µM-nitrate was achieved with a connecting tube volume of 0.5 mL and an injection volume of 0.5 mL. The method was applied to the determination of nitrate in tap water and spinach and the results were confirmed by ion chromatography.
Vegetable Water Potentiometry Electrode Membrane

"Sequential Injection Analysis Of Nitrites And Nitrates"
Anal. Chim. Acta 1995 Volume 315, Issue 3 Pages 321-330
M. T. Oms, A. Cerd&agrave; and V. Cerd&agrave;*

Abstract: A sequential injection system for the analysis of nitrate and nitrite is described. The sample and reagents are aspirated and mixed by flow reversal while being propelled to a reaction coil or to the detector. The determination of nitrite is based on the Griess-llosvay reaction. Nitrate is previously reduced by hydrazine in alkaline medium and analyzed as nitrite. The sequencing and overlap of the stacked zones are key parameters that have been studied together with concentrations of reagents, influence of temperature and potential interfering ions. Under the final optimal conditions up to 400 µM Of nitrite and nitrate can be analyzed, the detection limits being 0.07 ppm and 0.2 ppm respectively. The method has been tested with prepared standard samples, atmospheric aerosol filter extracts and wastewater samples. (14 references)
Particulates Waste Sequential injection Interferences Flow reversal

"Oxidative Detection Of Nitrite At An Electrocatalytic Dichloride-modified Electrochemical Sensor Applied For The Flow Injection Determination Of Nitrate Using A Copper-cadmium Reductor Column"
Anal. Chim. Acta 1996 Volume 319, Issue 1-2 Pages 111-120
Andrew P. Doherty*, Margaret A. Stanley, Donal Leech and Johannes G. Vos

Abstract: A vitreous C electrode (3 mm diameter) modified with the redox polymer [Ru(bipy)2(PVP)10Cl]Cl ~bipy = 2,2'-bipyridyl and PVP = poly-(4-vinylpyridine)~ was utilized in a FIA system for the determination of nitrate (I) following reduction to nitrite at a copperized cadmium reductor column. The single channel flow injection manifold consisted of a 50 µL sample injection loop, the reductor column (12 cm x 0.2 cm i.d.) packed with copperized cadmium chips and a thin-layer detection cell equipped with the working electrode at 0.95 V vs. SCE, a Ag/AgCl reference electrode and with the stainless steel body of the cell acting as the counter electrode. The composition of the carrier stream (0.5 mL/min) was not given. The calibration graph was linear from 10 µM-10 mM I and the detection limit was 5 µM. The RSD was 2% for 0.5 mM I. The method was applied to the determination of nitrate in commercial fertilisers and the results were confirmed by potentiometry.
Commercial product Amperometry Electrode Electrode Potentiometry Sensor Method comparison Reduction column

"Rapid Flow Injection Analysis Method For Successive Determination Of Ammonia, Nitrite, And Nitrate In Water By Gas-phase Chemiluminescence"
Anal. Chim. Acta 1997 Volume 349, Issue 1-3 Pages 11-16
Toyoaki Aoki* Shinji Fukuda, Yasuo Hosoi and Hiroshi Mukai

Abstract: A flow injection analysis method is presented in which an aqueous sample itself is used as the carrier stream and reagents are injected into this sample stream. Nitrite and nitrate were converted into nitric oxide (NO) in acidic media using iodide and titanium(III) as reducing agents, respectively. Ammonia was reacted with hypochlorite to generate a volatile compound. The NO or the volatile compound was transferred into air in a glass-tube separator and the volatile compound was subsequently converted into NO by combustion at 600°C. The NO was then reacted with ozone and the resulting chemiluminescence was detected. The determination limit was 1 x 10^-8 M for ammonia and nitrate, and was 1 x 10^-8 M for nitrite. The total time for the analysis of ammonia, nitrite, and nitrate in one sample was less than 3 min.
Water Chemiluminescence Gas phase detection

"Continuous-flow Determination System Based On Null-point Potentiometry Using A Nitrate Ion-selective Membrane"
Anal. Chim. Acta 1997 Volume 355, Issue 2-3 Pages 211-216
Hirokazu Hara* and Fumiko Izumiyama

Abstract: A new automated potentiometric analysis system for nitrate was developed. This system is based on the principle of null-point potentiometry. On either side of a nitrate ion-selective PVC membrane were the flowing sample and standard nitrate solutions. The concentration of the latter was automatically matched with that of the sample solution by controlling the dilution rate of a basic standard solution so that the membrane potential reached the 'null-point'. The determination without using a calibration graph was possible. The precision of five independent determinations was within 8% in the concentration range above 1 x 10^-5 mol dm?3. This system was applied to rain water analysis.
Electrode Potentiometry

"A Novel FIA Configuration For The Simultaneous Determination Of Nitrate And Nitrite And Its Use For Monitoring An Urban Waste Water Treatment Plant Based On N/D Criteria"
Anal. Chim. Acta 1998 Volume 359, Issue 1-2 Pages 173-183
D. Gabriel, J. Baeza, F. Valero and J. Lafuente*

Abstract: A novel FIA configuration for the simultaneous determination of nitrate and nitrite, and its automation for monitoring an urban wastewater treatment plant (WWTP) based on nitrification/denitrification criteria, are proposed. The detection range achieved is 0.25-50 mg L-1 for nitrate and 0.05-5 mg L-1 for nitrite (0.056-11.29 mg N-NO-3 L-1 and 0.015-1.52 mg N-NO-2 L-1). The max. sampling frequency is 180 samples/day and the Relative Standard Deviation (RSD, n=5) was 1.1% at 5 mg L-1 nitrite and 2.3% at 50 mg L-1 nitrate plus 1 mg L-1 nitrite. The particle size of the reductant (Cd) and the use of Cu as a catalyst influencing the stability of the reduction column were examined and an electronic calibration system was developed in order to increase the capacity of the equipment to operate unattended with a view to its use at WWTP. The max. unattended deployment time is four days. The proposed configuration was validated by analyzing real water samples at a pilot plant based on nitrification/denitrification criteria with optimal results.
Waste Spectrophotometry Process monitoring Remote instrument Optimization Reduction column

"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)
Environmental Waste Environmental Meat Commercial product Biamperometry Electrode Catalysis Reduction column Indirect Photochemistry UV reactor

"Catalytic Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate With A Flow Injection System"
Anal. Chim. Acta 1998 Volume 370, Issue 1 Pages 59-63
Zhang Zhi-Qi*, Gao Lou-Jun, Zhan Han-Ying and Liu Qian-Guang

Abstract: A catalytic spectrophotometric flow injection method is proposed for the simultaneous determination of nitrite and nitrate based on the catalytic effect of nitrite on oxidation of naphthol green B (NGB) by K bromate in H3PO4 medium and nitrate being reduced to nitrite by a Cd-coated Zn reductor column. The redox reaction was monitored spectrophotometrically by measuring the decrease in the absorbance of NGB at the max. absorption wavelength of 722 nm. A technique of double zone injection of the sample isolated by a reductor column is adopted with a single valve. The flow system produces two signals, one corresponds to the concentration. of nitrite and the other corresponds to the sum of both the ions. The detection limit is 0.5 µg L-1 for nitrite and 2.5 µg L-1 for nitrate. Up to 30 samples can be analyzed per h with a relative precision of ~2%. The procedure was successfully applied for the determination of nitrite and nitrate in natural waters.
Environmental Spectrophotometry Catalysis Kinetic Reduction column Redox Indirect

"Sequential Injection Sandwich Technique For The Simultaneous Determination Of Nitrate And Nitrite"
Anal. Chim. Acta 1998 Volume 371, Issue 1 Pages 63-71
A. Cerd&agrave;, M. T. Oms, R. Forteza and V. Cerd&agrave;*

Abstract: An automated sequential injection system for monitoring nitrate and nitrite in water samples is described. The method enables the simultaneous determination of both parameters with a single injection of sample. A sandwich arrangement, in which the sample is placed between two Griess reagent zones, is adopted. Nitrite is determined in one end of the sample zone by diazotization-coupling reactions and spectrophotometric detection of the azo dye formed. In the other end, nitrate is similarly determined after its online reduction to nitrite using a copperised cadmium column. The calibration is linear over the range 0.5-40 µmol L-1 nitrite and 2-100 µmol L-1 nitrate, the mid-range relative standard deviations being <2% in both the cases. Under optimized conditions the system has been applied to the determination of nitrate in tap, mineral and sea waters (the nitrite concentration. was below the detection limit) and the results have been compared with those obtained by ion chromatography and a flow injection system based on the same reactions.
Water Mineral Sea Spectrophotometry Sequential injection Sandwich technique Simultaneous analysis Optimization Method comparison

"In Situ Determination Of Silicic Acid In Sea Water Based On FIA And Colorimetric Dual-wavelength Measurements."
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 157-166
Julien Floch, St&eacute;phane Blain*, Dominique Birot and Paul Treguer

Abstract: A method has been developed to determine silicic acid in sea water with submersible chemical analyzer. It is based on direct FIA, for fast and discrete measurements, and dual wavelength treatment of the signal to correct the refractive index interference, the main factor that affects in situ anal. Fast anal. rate (60 discrete samples per h) is achieved because of a very short lag time between sampling and injection of the sample into the carrier stream. This allow high resoln. in situ measurements, giving access to small scale transitory processes concerning nutrients cycles in ocean ecosystem. This colorimetric method is based on the formation of beta silicomolybdic acid reduced in intense colored molybdenum blue. Rapid and non temperature dependent reduction is obtained by using tin(II) chloride as reductor. There is little interference from phosphate in the usual conditions at sea. For in situ applications, we gave special attention to the effect of temperature (0-30°C) and salinity (0-34) variations that can greatly influence the silicomolybdate complex formation. This reaction zone has to be thermostated and kept above 20°C. A max. signal enhancement of 12% is encountered when samples salinity varies from 34 to 0 (PSS78), but no significant deviations are observed between 34 and 28 (PSS78). The precision of the method is 1% for silicate concentrations. above 5 µM and the limit of detection is 0.3 µM. The comparison of the measurements obtained by this method and the usual flow sequential anal. system showed good agreement. The method has been implemented on an in situ chemical analyzer and simultaneous silicic acid and nitrate concentration. measurements were carried out in coastal waters.
Sea Spectrophotometry Remote instrument Dual detection Interferences Simultaneous analysis Manifold comparison

"Configuration With Internally Coupled Valves To Overcome Shortcomings In The Simultaneous Determination Of Nitrite And Nitrate By Flow Injection Analysis"
Talanta 1988 Volume 35, Issue 10 Pages 810-812
B. Bermudez, A. Rios, M. D. Luque de Castro and M. Valcarcel

Abstract: Signal instability due to compaction of the Cu-coated cadmium reductant grains can be counteracted by use of the flow injection manifold shown, which incorporates internally coupled valves with the reductant column in the loop of the secondary valve in order to reverse the flow-through the column. The effect is more marked for smaller grain sizes; larger grain sizes give a more stable, but smaller signal. Coating of the cadmium grains with Cu is unnecessary.
Spectrophotometry Reduction column Reverse Simultaneous analysis Valve

"Chemiluminescence Determination Of Nitrate With Photochemical Activation In A Flow Injection System"
Talanta 1995 Volume 42, Issue 3 Pages 437-440
Liu Renmin, Liu Daojie, Sun Ailing and Liu Guihua

Abstract: A flow-through photochemical reactor was used for the determination of nitrate in a FIA system, based on photochemical activation and chemiluminescence reactions (diagrams given). The carrier solution (1.5 ml/min) was H2SO4 of pH 5 and the reagent solution was 50 µM-luminol with 0.1 M NaOH (0.5 ml/min). An iminodiacetyl ligand exchange resin was used in the FIA system to remove the interference of Fe3+, Cu2+, Co2+ and Ni2+. The chemiluminescence signal was recorded with a XWT-S platform recorder. The sampling frequency was 60/h. The calibration graph was linear from 70 nM-0.1 mM. The RSD were 0.76-0.97%. The method was applied to the determination of nitrate in natural waters. Recoveries were 96-103%.
Environmental Chemiluminescence Photochemistry Resin Interferences

"Flow Injection Analysis Spectrophotometric Determination Of Nitrite And Nitrate In Water Samples By Reaction With Proflavin"
Talanta 1996 Volume 43, Issue 2 Pages 239-246
R. Segarra Guerreroa, C. Gom&eacute;za and J. Mart&iacute;nez Calatayudb,*

Abstract: A flow injection manifold is proposed for determination of nitrite based on the reaction with 3,6-diamino acridine (proflavin sulfate) in hydrochloride acid medium. The assembly is adapted for nitrate determination by including a reductive column filled with copperized cadmium. The influence of foreign substances is also studied. The method gives a linear calibration graph over the range 0.06-4 mg L-1 nitrite, with an RSD <0.5%. The method was applied to nitrite and nitrate determinations in either waste water or coastal marine water samples. For the determination of nitrites a water sample was merged in a mixing chamber with a reagent stream of 0.2 mM proflavin/L M HCl and the resulting solution was injected into a carrier stream (1.79 ml/min) of water. The absorbance was then measured at 328 nm. For the determination of nitrates a copperized Cd column (10 cm x 5 mm i.d.; particle size 4 mm) was inserted into the system before the mixing chamber to reduce nitrate to nitrite. Calibration graphs were linear for 0.06-4 mg/l of nitrite with a RSD (n not given) of >0.5%. The effects of foreign compounds on nitrite determination are tabulated.
Sea Waste Spectrophotometry Interferences Reduction column

"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.
Environmental Beer Cube Food Environmental Meat Sample preparation Spectrophotometry Interferences Column Reduction column

"Flow Injection Spectrophotometric Determination Of Nitrate In Electrolyte Of Lead-acid Batteries"
Talanta 1997 Volume 45, Issue 2 Pages 265-271
F&aacute;bio R. P. Rocha* and Joaquim A. N&oacute;brega

Abstract: Electrolytes of lead-acid batteries can contain several impurities that reduce battery performance and lifetime. Nitrate ions are among these species because they can be reduced to ammonium in the lead electrode. In this work, an analytical method was developed to determine this anion in electrolytes of batteries used in telephone systems, in which nitrate concentration must be lower than 10 mg L-1. The procedure consists in the reduction to nitrite in a copperized cadmium column followed by Griess's modified reaction. Due to the high sensitivity of this methodology, a large dispersion flow diagram (dispersion coefficient = 27.8) was projected. Thus, it was possible to eliminate the Schlieren effect and to obtain a NH3/NH+4 buffer in the sample zone in a suitable pH for reduction reaction (pH 8). Negative interference due to iron(III) was overcome by addition of excess iron (200 mg L-1). A relocatable filter was used to remove iron(III) hydroxide precipitate. This avoided adsorption on the surface of the filings and increase of back pressure. The analytical frequency is 80 measurements/h and the detection limit was estimated as 0.3 mg L-1 in a 99.7% confidence level. A 2.2% relative standard deviation was obtained in a repeatability study (n = 10) by using a 25 mg L-1 nitrate solution in a 3.6 mol L-1 sulfuric acid medium. Recoveries from 95.5 to 104% were obtained by spiking 5.00 or 10.0 mg L-1 of nitrate in samples of battery electrolyte.
Electrolyte Spectrophotometry

"Full Automated Robotic Method For The Determination Of Chloride, Nitrite And Nitrate In Cured Meat Products"
Talanta 1998 Volume 46, Issue 5 Pages 969-976
A. Velasco-Arjona, J. A. Garc&iacute;a-Garrido, R. Quiles-Zafra and M. D. Luque de Castro*

Abstract: A completely automated method to determine the most common parameters in cured meat products is proposed. The approach to full automation is based on the coupling of a robotic station for development of preliminary operations (namely weighing of the sample, grinding, leaching, filtration and transport to the aspiration zone) and a continuous unsegmented manifold for derivatization and spectrophotometric monitoring of the reaction colored products. This assembly works in an unattended fashion thus eliminating the bottleneck produced by the determination of these parameters in routine laboratories. The good agreement between results obtained by the proposed method and those from conventional methods for target analytes confirms its excellent performance and usefulness.
Meat Spectrophotometry Sample preparation Automation Robot Method comparison

"Rapid Determination Of Nitrogen, Phosphorus And Potassium In Fertilizers By Flow Injection Analysis"
Analyst 1977 Volume 102, Issue 1219 Pages 714-722
E. H. Hansen, F. J. Krug, Animesh K. Ghose and J. Ruzicka

Abstract: Nitrate, K, phosphate, and NH3 were determined in fertilizers by flow injection analysis of samples of 30 µL (and as low as 5 µL) using potentiometric and spectrophotometric detection; 85-120 samples per h were analyzed with high reproducibility and low reagent consumption. The results agreed well with those obtained by the fertilizer manufacturers by conventional techniques. Based on the flow injection technique and routinely using sample injections of 30 µL, and as low as 5 µL, reliable and sensitive methods for the determination of nitrate, potassium, phosphate and ammonia in fertilisers are described in which potentiometric and spectrophotometric detection is used. At sampling rates of 85-120 samples per hour high reproducibility of measurement and low reagent consumptions were achieved. The good agreement between the results obtained with the flow injection methods and those attained by the manufacturer of the fertilisers with conventional techniques shows that flow injection analysis is potentially suitable for the routine analysis of these and similar substrates.
Commercial product Electrode Electrode Potentiometry Spectrophotometry Method comparison

"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.
Environmental Commercial product Geological Environmental Waste Electrode Apparatus Interferences

"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.
Geological Environmental GC Conductometry Conductometry Closed loop

"Flow Injection Voltammetric Determination Of Nitrate After Reduction To Nitrite"
Analyst 1983 Volume 108, Issue 1285 Pages 464-469
Arnold G. Fogg, Antoine Y. Chamsi and Mohamed A. Abdalla

Abstract: Nitrate can be determined conveniently by chemical reduction to nitrite, which is then injected directly into an acidic bromide eluent in a flow injection system and monitored using its reduction signal at a glassy carbon electrode held at + 0.3 V versus a saturated calomel electrode. Chemical reduction was best carried out on a batch basis but partial success was experienced in using a method in which a nitrate sample solution was passed continuously through a cadmium sponge column and then through the injection loop of the flow injection valve from which aliquots were injected into the flow injection system. Determinations were also made by injection of nitrate sample solution directly into an acidic bromide eluent and reducing the nitrate on-line with cadmium wire.
Electrode Voltammetry

"Differential Pulse Polarographic Determination Of Nitrate As 3-nitrobenzoic Acid And Other Nitro-derivatives"
Analyst 1988 Volume 113, Issue 6 Pages 979-981
Arnold G. Fogg, S. Paul Scullion and Tony E. Edmonds

Abstract: A 1 mL portion of NO3- solution was mixed with 3 mL of 0.02 M benzoic acid in concentrated H2SO4. The mixture was diluted to 25 ml, the solution was deoxygenated with N, and the differential pulse polarographic peak at -0.13 V was measured by using a flow injection amperometric sensor equipped with a vitreous-carbon working electrode and Ag - AgCl reference electrode. Calibration graphs were rectilinear over the range 10 µM to 5 mM; coefficient of variation (n = 6) were 8% at 30 µM and 2% at 0.3 and 3 mM. Other aromatic and heterocyclic compounds were examined as substrates for nitration, but were less suitable.
Electrode Polarography

"Versatile Manifold For The Simultaneous Determination Of Ions In Flow Injection Analysis"
Analyst 1988 Volume 113, Issue 10 Pages 1551-1555
Peter C. Hauser, Susie S. Tan, Terence J. Cardwell, Robert W. Cattrall and Ian C. Hamilton

Abstract: A flow injection analysis system is described for the simultaneous determination in plant nutrient solution of K+, Ca(II), NO3- and Cl- by potentiometry, and NH4+ and PO43- by spectrophotometry. Diagrams of the manifold and the spectrophotometric transducer are given. Potentiometric measurements were made with PVC-based ion-selective membranes; the carrier stream was 0.2 M Na acetate buffer. Ammonium ion was determined by the gas diffusion method with use of cresol red and thymol blue. Absorbance was measured at 605 nm. The calibration graph covered the range from 0.5 to 25 mg L-1 as N. Phosphate was determined by the molybdenum blue method, with absorbance measurement at 820 nm; the calibration graph covered the range from 0.5 to 25 mg l-1. Results agreed well with expected values.
Commercial product Electrode Electrode Electrode Electrode Potentiometry Spectrophotometry Gas diffusion Simultaneous analysis

"Re-examination Of The Determination Of Environmental Nitrate By Reduction With Hydrazine"
Analyst 1988 Volume 113, Issue 7 Pages 1117-1120
Alexander J. Kempers and Arno G. Luft

Abstract: The determination of nitrate as nitrite remains the method of choice owing to the accuracy with which low concentrations of nitrite can be detected. A manual procedure for the reduction of nitrate to nitrite using hydrazine sulphate (HS) was described as impractical owing to the capricious nature of the reaction. The homogeneous catalyzed reduction proposed in this work compares well with the usual heterogeneous catalyzed cadmium reduction column technique without, however, being subject to interfering substances, and offers the possibility of increasing the number of simultaneous nitrate reductions using sample volumes down to a few microlitres. The relative standard deviation of the method is 0.7% with a detection limit of 0.2 µmol l-1 of nitrate. It is demonstrated that uncontrolled fluctuations in the concentration of oxygen, present during the reduction, were the main cause of the earlier erratic results. The Mg2+ ion, also responsible for complete suppression of the reduction, was inactivated by pyrophosphate.
Environmental Spectrophotometry

"Assessment Of Online Nitration Reactions As A Means Of Determining Nitrate By Reverse Flow Injection With Reductive Amperometric Detection At A Glassy Carbon Electrode"
Analyst 1989 Volume 114, Issue 5 Pages 579-581
Arnold G. Fogg, S. Paul Scullion and Tony E. Edmonds

Abstract: Five compounds were investigated for use as on-line reagents in concentrated sulphuric acid for the reductive reverse flow injection amperometric determination of nitrate as a nitro derivative at a glassy carbon electrode. The sulphuric acid was diluted rapidly on injecting the reagent solution into a sample carrier stream and therefore the nitration reaction, which generally only takes place at sulphuric acid concentrations of greater than about 70%, had to be rapid. Thiophene-2-carboxylic acid was found to be the most suitable reagent of those studied. The nitration reaction was sufficiently rapid and the first of two reduction steps was at -0.19 V versus SCE (as indicated by linear sweep voltammetry); hence the determination was free from interference by dissolved oxygen. Problems associated with contamination of the electrode surface with reduction product, which caused loss of signal after making repeated injections over an extended period, remained.
Amperometry Electrode Reverse

"Reductive Reverse Flow Injection Amperometric Determination Of Nitrate At A Platinum Electrode After Online Reduction To Nitrosyl Chloride In Concentrated Sulfuric Acid Medium Containing Chloride"
Analyst 1990 Volume 115, Issue 5 Pages 599-604
Arnold G. Fogg, S. Paul Scullion and Tony E. Edmonds

Abstract: Concentrated H2SO4 (25 µL) was injected into a 2 M HCl carrier stream (6 mL min-1) containing the NO3- sample; NO2Cl and Cl2 formed were detected at a Pt electrode at +0.07 V (vs. Ag - AgCl). Dispersion was reduced to increase the signal and reduce base-line noise by using a 40-cm-long single bead string reactor to connect the injection valve and detector. The calibration graph was rectilinear from 0.9 to 5 µM; no interference was observed.
Electrode Amperometry Dispersion Detector Interferences Reverse Single bead string reactor

"Spectrophotometric Or Coulometric Determination Of Nitrate With An Electrochemical Reductor Using Flow Injection"
Analyst 1990 Volume 115, Issue 4 Pages 425-430
Ryuji Nakata, Minoru Terashita, Akihiko Nitta and Keiko Ishikawa

Abstract: The flow-through column electrode, with Cu and Cd deposited on glassy carbon beads, as described previously by Nakata (Fresenius Z. Anal. Chem., 1984, 317, 115) was used. The NO3- was reduced to NO2- at -0.85 to -1.05 V vs Ag - AgCl in NH4OH buffer, pH 10.0. The NO2- was determined by conventional colorimetry with a detection limit of 0.7 µm and a coefficient of variation (n = 10) of 0.52% for 10 µm. By using a column electrode with Ag deposited on the grains, as an O2 scrubber at -0.8 V, before the Cu - Cd electrode, the NO3-1 could be determined coulometrically. The limit of detection was 2 µm with coefficient of variation (n = 10) of 1.9% for 50 µm and 3.3% for 10 µm. The method was applied in the analysis of waters, the results obtained were in close agreement with those obtained by ion chromatography.
Coulometry Electrode Electrode Spectrophotometry Column Glass beads Buffer pH Detection limit Method comparison

"Direct Reductive Amperometric Determination Of Nitrate At A Copper Electrode Formed Insitu In A Capillary-fill Sensor Device"
Analyst 1991 Volume 116, Issue 6 Pages 573-579
Arnold G. Fogg, S. Paul Scullion, Tony E. Edmonds and Brian J. Birch

Abstract: A method has been developed for determining nitrate amperometrically by direct reduction at a freshly deposited copper electrode surface in a capillary-fill device (CFD). Copper(II) is added to the nitrate sample which is then taken up into the device. The potential of the screen-printed carbon electrode is held at -0.75 V versus the screen-printed silver reference electrode. At this potential, copper is plated onto the carbon electrode forming a freshly prepared copper electrode. At the same time dissolved oxygen is reduced. The potential is then scanned to more negative potentials and the signal at -0.90 V, due to the reduction of the nitrate, is measured. The method for determining nitrate given here is preliminary to the production of CFDs in which chemical reagents, copper sulphate and potassium hydrogen sulphate (used to produce the acidity), are screen-printed or otherwise coated onto the upper plate within the device.
Amperometry Electrode Electrode Electrode Voltammetry Sensor Reverse Apparatus Detector

"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.
Environmental Environmental Potentiometry Electrode Electrode Electrode Electrode Sample preparation

"Sequential Determination Of Calcium And Nitrate Ions In Waters By Potentiometric Flow Injection"
Analyst 1993 Volume 118, Issue 12 Pages 1527-1532
Julian Alonso-Chamarro, Jordi Bartrol&iacute;, Siao Jun, Jose Luis F. C. Lima and M. Concei&ccedil;ao B. S. M. Montenegro

Abstract: Water (100 µL) was injected into a carrier stream (3.5 ml/min) of 0.02 M sodium acetate containing 4 µM-calcium nitrate and the solution passed through a mixing coil (no dimensions given) before detection with a calcium tubular potentiometric electrode (described). The solution was then mixed with an auxiliary carrier solution (3.5 ml/min) of 0.02 M lead acetate/0.01 M lead oxide before detection with a nitrate tubular potentiometric electrode (described). Diagrams of the flow injection manifold and the tubular electrode design are given. The response slope and lower limit of linear response were 53.4 mV/decade and 10^-4.3M, respectively, for the nitrate sensor, and 31.3 mV/decade and 10^-4.75M, respectively, for the calcium sensor. The RSD (n > 4) was 1% and the sample throughput was 145/h. Recoveries were quantitative. Results agreed with those obtained by AAS and spectrophotometry. The method permits the simultaneous determination of calcium and nitrate in most water samples (excluding those with a high saline content).
Water Potentiometry Dual detection

"Speciation Of Nitrogen In Wastewater By Flow Injection"
Analyst 1996 Volume 121, Issue 1 Pages 13-17
A. Cerd&agrave;, M. T. Oms, R. Forteza and V. Cerd&agrave;

Abstract: For joint nitrite and nitrate determination, the sample was aspirated (0.36 ml/min) through a column of Amberlite XAD-7 resin before being mixed with a reductant stream (1.2 ml/min) containing 3 g/l hydrazine sulfate, 6 mg/l CuSO4, 1 g/l ZnSO4 and 20 g/l NaOH. The mixture was passed through a 2 m reaction coil maintained at 40°C; it was then injected into an aqueous carrier stream (1.2 ml/min), which was mixed with a reagent stream (1.2 ml/min) containing 20 g sulfanilamide and 0.5 g N-(1-naphthyl)ethylenediamine in 25 mL 37% HCl. The absorbance was then measured at 540 nm, from which the absorbance at 420 nm was subtracted. Nitrite was determined by the above procedure, except that the reductant stream was replaced by water. Nitrate was determined by difference. For total N determination, the sample (0.2 ml/min) was mixed with a stream (0.36 ml/min) containing 15 g/l alkaline potassium persulfate and 3.5 g/l sodium tetraborate. The mixture was passed through a 3 m coil and irradiated at 254 nm for 50 s. The irradiated sample was then treated as described above for joint nitrite and nitrate determination, except that the resin column was not used. Calibration graphs were linear up to 220, 240 and 1000 µM nitrite, nitrate and total N, respectively; detection limits were 2, 8 and 30 µM. The RSD (n = 10) were 1.5%, 2.3% and 3% for nitrite, nitrate and total N determination, respectively.
Waste Spectrophotometry Amberlite Speciation

"Simultaneous Assay Of Nitrite, Nitrate And Chloride In Meat Products By A Flow Injection Method"
Analyst 1996 Volume 121, Issue 10 Pages 1393-1396
I. M. P. L. V. O. Ferreira, J. L. F. C. Lima, M. C. B. S. M. Montenegro, R. P&eacute;rez Olmos and A. Rios

Abstract: Sample was homogenized and extracted with hot water and the extract was purified and filtered. A portion (100 µL) of the filtrate was injected into a carrier stream (2.9 ml/min) of 50 mM Na2SO4/0.02 mM NaCl of a flow injection manifold (schematic shown). Chloride (I) was determined potentiometrically a tubular ISE (cf. Ferreira et al., Fresenius' J. Anal. Chem., 1993, 374, 314). The carrier was mixed with a buffer stream (0.5 ml/min) of NH4Cl/sodium tetraborate/Na2EDTA and split into two. One stream passed through a Cd/Cu column to reduce nitrate (II) to nitrite (III). The two streams subsequently passed through a confluence point and were mixed a reagent stream (1 ml/min) of acidified sulfanilamide/N-(1-naphthyl)ethylenediamine dihydrochloride and the absorbance was measured (wavelength not given). As each channel had a different residence time, two peaks were obtained, one for nitrite III and one for total N: II was measured by difference. The calibration graphs were linear from 0.01-0.1 M I, up to 104 ppm II and from 0.03-0.2 ppm III. RSD (n = 10) were 2.5, 0.7 and 1.1%, respectively, for I, II and III.
Meat Meat Potentiometry Electrode Electrode Reduction column Buffer Sample splitting

"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)
Environmental 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)
Environmental Environmental Commercial product Meat Spectrophotometry Automation Injection technique UV reactor Photochemistry Buffer Interferences EDTA Differential detection

"Indirect Determination Of Nitrate By Electrothermal Atomic Absorption Spectrometry Using An Online Cadmium Microcolumn"
Analyst 1998 Volume 123, Issue 7 Pages 1561-1564
E. Vereda Alonso, M. T. Siles Cordero, M. P. Caballero Torres, A. Garc&iacute;a de Torres and J. M. Cano Pav&oacute;n

Abstract: The proposed indirect automatic method is based on the reduction of nitrate to nitrite using a cadmium reductant microcolumn where the flow of the sample through the microcolumn oxidizes the metallic cadmium to Cd(II), which is measured by electrothermal atomic absorption spectrometry. The automatic system is achieved simply by replacing the sample tip of the autosampler arm with the reductant microcolumn. This system results in a powerful integrated system which permits fully automated operation, avoiding time-consuming manual work and enhancing the sensitivity. The manifold was evaluated with respect to accuracy, precision and sensitivity for nitrate determination in water, the detection limit achieved being 0.05 g mL-1 (3s) with a sampling rate of about 35 h-1. A 2.3% relative standard deviation was obtained in a repeatability study (n = 11) at the 0.2 g mL-1 level of nitrate and 2.6% at the 8.0 g mL-1 level. Some ions which commonly occur with nitrate in water samples, such as Na+, Ca2+ and Mg2+, interfered to a certain extent, although these interferences were minimized by passing of the sample through an Amberlite cation-exchange resin. The method was applied to samples of bottled and spring waters with good results. The matrix effects were minimized by using the standard addition method.
Water Spectrophotometry Reduction column Extraction Indirect

"High Sensitivity, Continuous-flow Thermochemical Analyzer"
Anal. Chem. 1979 Volume 51, Issue 2 Pages 278-283
Richard S. Schifreen, Carolyn Sue Miller, and Peter W. Carr

Abstract: A flow enthalpimeter for use with two fluid streams has been designed. It is based on a related device for use with one fluid stream and a bed of catalyst. Satisfactory results were obtained only when the two thermistors, which comprise part of a differential temperature measurement system, are subjected to the same net flow. In addition, any volume located between the point of reagent mixing and the adiabatic column must be minimized. Assays for mineral acid, calcium ion, and nitrite based upon their reaction with tris(hydroxymethy1)- aminomethane, ethylene bis(oxyethylenenitri1o)tetraacetic acid, and sulfamic acid, respectively, have been developed. Detection limits ranged from 10 pM to l mM, depending upon the heat of reaction and achievable baseline stability. Sample volumes of 120 pL and a flow rate of 2.5 mL/min allow for a throughput of nearly 60 samples/h. In general, sample volume, concentration, and flow rate affected the signal height and width in a fashion similar to that observed with an immobilized enzyme analyzer based on a related flow system. The chief differences in behavior occur at low sample concentration.
Enthalpimetry Enzyme

"Flow-through Electrode Unit For Liquid Membrane Electrodes"
Anal. Chem. 1980 Volume 52, Issue 13 Pages 2100-2104
D. S. Papastathopoulos, E. P. Diamandis, and T. P. Hadjiioannou

Abstract: The construction of a flow-through electrode unit for the preparation of liquid membrane electrodes is described. The construction is based on the use of a triangular piece of glass frit embedded in a plastic block. The glass frit serves as an inert matrix holding the electroactive liquid phase. A hole drilled through the frit forms the sensing path for the test solution channeling. The unit is equipped with an internal reference solution-Ag/AgCl electrode system and a reservoir for ion exchanger storage. Flow-through liquid membrane electrodes for calcium, nitrate, perchlorate, and picrate Ions are prepared by using conventional Ion exchangers for the evaluation of the constructed unit. The electrodes are tested for their stability, reproducibility, response time, and working range under various continuous-flow conditions.
Electrode Electrode Electrode

"Continuous-flow Reduction Of Nitrate To Ammonia With Granular Zinc"
Anal. Chem. 1986 Volume 58, Issue 7 Pages 1590-1591
Robert M. Carlson

Abstract: A column of granular zinc pre-treated with 5% CuSO4 solution was used as reductant. Samples were mixed with a diethylenetriaminepenta-acetic acid - KOH solution, followed by the addition of K H gluconate, and then passed over a gas-permeable membrane. The liberated, diffused NH3 was collected in a water stream and measured by its electrical conductivity. Nitrate was determined by difference after running the sample with and without the reduction column. Recoveries of 99.6, 99.1 and 98% were obtained for standards containing 5 mM , 10 mM and 20 mM NO3-, respectively. Various common ions at 50 to 100 mM did not interfere.
Conductometry Interferences Reduction column Membrane

"A Fast Determination Of Nitrate In Rain And Surface Waters By Means Of UV Spectrophotometry"
Fresenius J. Anal. Chem. 1976 Volume 280, Issue 5 Pages 365-368
J. Slanina, W. A. Lingerak and L. Bergman

Abstract: Organic substances are the main interference in the direct U.V. spectrophotometric determination of nitrate at 210 nm. An active carbon filter (Filopur) is therefore proposed which adsorbs all organic interferences. With this filter the U.V. spectrophotometric method gives the same results as the Na-salicylate method. The reproducibility is generally better than 5 %. One determination takes 50 s.
Rain Surface Spectrophotometry Activated carbon

"Fast Determination Of Nitrate In Small Samples Of Rain And Surface Waters By Means Of UV Spectrophotometry And Flow Injection Analysis"
Fresenius J. Anal. Chem. 1978 Volume 289, Issue 1 Pages 38-40
J. Slanina, F. Bakker, A. G. M. Bruijn-Hes and J. J. M&ouml;ls

Abstract: An UV-spectrophotometric determination of NO3- in small samples (0.5 mL) of rain and surface waters is described. A variant of flow injection analysis is used in combination with an active C filter for removal of organic interferences. The accuracy and the reproducibility of the method are >3%. One determination takes 30 s.
Surface Rain Spectrophotometry Activated carbon Interferences Small sample

"Flow Analysis For The Determination Of The Main Components Of Waters, Rain Water And Drinking Water"
Fresenius J. Anal. Chem. 1983 Volume 314, Issue 7 Pages 627-633
H. F. R. Reijnders, P. H. A. M. Melis und B. Griepink

Abstract: A survey of the literature concerning flow-through determination of the main components in various types of water is given. These components are: alkalinity, chloride, nitrite, nitrate, phosphate, sulphate, ammonium, potassium, lithium, sodium, barium, calcium, magnesium and strontium. Details with regard to e.g. type of water, range of the method, interferences etc. are given in a separate compilation which is available from the editor upon request.
Water Rain Review

"Determination Of Nitrate In Natural Waters By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1984 Volume 319, Issue 5 Pages 506-509
Susumu Nakashima, Masakazu Yagi, Michio Zenki, Akinori Takahashi and Kyoji T&ocirc;ei

Abstract: The sample is injected into a carrier solution containing 0.8 g L-1 of Na4EDTA and 3 g L-1 of NH4Cl (pH ~8.1), and the stream passes through copperized cadmium to reduce NO3- to NO2-. The reagent (containing 552 mg L-1 of m-phenylenediamine dihydrochloride and 200 mg L-1 of 4'-aminoacetophenone; pH 2) is added, the solution are mixed at 45°C, and the absorbance of the product is measured at 456 nm. The detection limit is 1.5 ppb with injection of 650 µL of water, and, at 0.1 to 0.3 ppm of nitrate-N, the coefficient of variation is <1%. Nitrite present in the sample is determined separately and corrected for. Of the foreign ions examined, 50 ppm of Ca(II), Mg(II), Na+, K+, NH4+, HCO3-, SO42-, Cl-, SiO32- or H2PO4- did not interfere in the determination of 0.2 ppm of nitrate-N. Results for NO3- in 10 natural water samples are reported.
Environmental Spectrophotometry Heated reaction Interferences Reactor

"Determination Of Nitrate And Nitrite By Continuous Liquid-liquid Extraction With A Flow Injection Atomic Absorption Detection System"
Fresenius J. Anal. Chem. 1986 Volume 323, Issue 1 Pages 50-53
Mercedes Gallego, Manuel Silva and Miguel Valc&aacute;rcel

Abstract: An automatic analyzer. constructed from PTFE tubing (0.5 mm i.d.) is described, in which equal volume of the sample solution, containing 0.1 to 2.2 µg mL-1 of NO3- or 0.5 to 10 µg mL-1 of NO2-, and the carrier solution [aqueous CuSO4 solution, 0.15 M hydroxylammonium sulfate, and 5 mL of phosphate buffer solution (pH 4.5)] are mixed by passing through a 900-mm coil, and are then extracted in a 3.6-m coil by a segmented stream (0.36 mL min-1) of a solution of 2,9-dimethyl-1,10-phenanthroline in 100 mL of isobutyl methyl ketone. The organic phase (130 µL) is injected into a flow (3 mL min-1) of water which is passed into a Perkin-Elmer 380 AAS apparatus for detection. Detection limits were 0.04 µg mL-1 for NO3- and 0.4 µg mL-1 for NO2-. For the analysis of mixtures of NO3- and NO2-, NO2- can be oxidized to NO3- by Ce(IV), or reduced to N by sulfamic acid. Thiocyanate from SCN-, ClO3- and ClO4- are tolerated at concentration. equal to that of NO3-.
Spectrophotometry Sample preparation Extraction Interferences Organic phase detection

"Flow Injection Determination Of Nitrate In Natural Water With Copper And Copperized Cadmium Tubes In The Reaction Manifold System"
Fresenius J. Anal. Chem. 1986 Volume 325, Issue 2 Pages 150-152
J. F. van Staden, A. E. Joubert and H. R. van Vliet

Abstract: The apparatus described previously (cf. Van Staden, Anal. Abstr., 1983, 44, 1H58) was used to determine NO3- by its reduction to NO2- by passing the sample through a copperized cadmium tube, followed by diazotization of sulfanilamide, coupling of the product with N-1-naphthylethylenediamine dihydrochloride and measuring the absorbance of the formed azo-dye at 520 nm. The life of the copperized tube (otherwise ~40 determinations) is extended about fivefold by the addition of a copper tube (20 cm x 1 mm) in front of the cadmium tube (1 m x 1 mm, coated by passing through it a solution containing Cu and EDTA). A Hellma flow-through cell was used with a Unicam SP6-550 UV - visible spectrophotometer. A flow diagram is given, showing the flow rates of the reactant solution; injection of 300 µL samples containing 0.05 to 2 mg L-1 of NO3- at a rate of 50 h-1 was carried out; the coefficient of variation were 1.5%.
Ground Spectrophotometry

"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.
Environmental Plant Juice Musts Sample preparation Method comparison Review Tecator

"Flow Injection Analysis With Electrochemical Detection"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 691-697
K. Cammann

Abstract: Two combinations of flow injection analysis with electrochemical detection are discussed. The use of potentiometry with ion-selective electrodes is illustrated by the determination of NO3- alone and simultaneously with Na+, K+, Ca(II), HCO3- and Cl- in drinking water, of Al without a reference electrode, of SO2 in grape juices, and of glucose in biological fluids. The apparatus is described and the experimental conditions are given. A hanging-mercury-drop electrode (at 0 V vs. Ag - AgCl) was used for the amperometric detection of ascorbic acid in a buffer (pH 4.7) stream.
Biological fluid Juice Water Amperometry Electrode Electrode Potentiometry Interferences Review

"New Flow Injection Analysis Methods For The Determination Of Ions. 2. Sulfate, Sulfite And Nitrate, Nitrite"
Fresenius J. Anal. Chem. 1988 Volume 330, Issue 6 Pages 494-497
N. Almhofer und F. Frenzel

Abstract: The apparatus described previously (see Part I, later in this section) is used, with measuring electrodes of Pb - PbSO4 for SO42-, Pb for SO32-, Sn for NO3-, and Sb for NO2-. Measurement is potentiometric for SO42-, otherwise amperometric. The measurement ranges are 50 µM to 10 mM for SO42- and NO3-, 10 µM to 10 mM for SO32-, and 0.1 to 10 mM for NO2-. Results for various waters are given, showing a typical coefficient of variation of 1.5% for SO42- and SO32- and 2.5% for NO3- and NO2-. Selectivity coefficient are quoted and instructions are given for electrode preparation. The measurement and calibration procedures are as described previously, except that the carrier stream consists of 100 mL of 0.1 mM Na2SO4 plus 200 mL of ion buffer (10 mM NaClO4 - 10 mM HClO4) diluted to 1 l, and cations (especially Ca) must be exchanged for Na beforehand. Results for analysis of waters are presented.
Environmental Amperometry Electrode Potentiometry Apparatus

"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.
Environmental Spectrophotometry Sample preparation Extraction Robot

"A Novel Flow Injection System For Simultaneous Determination Of Nitrate And Nitrite Based On The Use Of A Zinc Reductor And A Bulk Acoustic Wave Impedance Detector"
Microchem. J. 1998 Volume 59, Issue 3 Pages 341-350
Xiao-Li Su, Po Chen, Xiao-Ge Qu, Wan-Zhi Wei and Shou-Zhuo Yao

Abstract: A novel flow injection system was developed for the simultaneous determination of nitrate and nitrite present in water, foodstuffs, and human saliva. The system is based on the use of a Zn-filled reduction column and a bulk acoustic wave impedance sensor (BAWIS) as detector. With water as carrier stream, both nitrate and nitrite are converted online to NH3, whereas with sulfamic acid, only nitrate is converted to NH3. The NH3 formed diffuses across a PTFE membrane and is trapped in an acid stream causing a change in the solution conductance, which was monitored by a BAWIS detector. At a throughput of ~60 h-1, the proposed system exhibited a linear response to the concentration. of nitrate and nitrite from 2.5 µM to 1.00 mM, with detection limits of 1.7 and 1.8 µM, respectively, and the relative standard deviation of the peak heights (n = 6) ranged between 0.83 and 1.75% for the entire working range. In anal. of real samples, the simultaneous determination of nitrate and nitrite was achieved by the proposed method with a simple change of the carrier stream between water and sulfamic acid, and the results agreed well with those of conventional colorimetry. (c) 1998 Academic Press.
Water Food Saliva Conductometry Sensor Gas diffusion Reduction column Teflon membrane Simultaneous analysis

"Simultaneous Determination Of Nitrate And Nitrite In Biological Samples By Multichannel Flow Injection Analysis"
Anal. Biochem. 1995 Volume 231, Issue 2 Pages 383-386
Phillip F. Pratt, Kasem Nithipatikom and William B. Campbell

Abstract: In a multichannel flow injection analyzer. (a modified Automated QuikChem Ion Analyzer, Lachat Instruments Inc., Milwaukee, WI, USA; modifications described), the sample was divided into two channels, one representing total nitrite (obtained by Cd reduction of nitrate to nitrite) and the second representing only nitrite. The absorbance of the product of the reaction of nitrite with Greiss reagent was measured at 540 nm. The detection limit was 25 nM-nitrite or -nitrate. The calibration graph was linear from 25 nM to 20 µM nitrite. Recovery from bovine coronary endothelial cells was 95% for both ions. The method was applied to the determination of the ions in serum and bovine coronary artery endothelial cells and rat cerebellar granule cells. An automated method for the simultaneous determination of nitrite and nitrate in biological samples by using a multichannel flow injection analyzer has been developed. The method was based on the reaction of nitrite with Greiss reagent. The sample solution was injected and equally divided into two channels; channel one (1) represented total nitrite obtained by cadmium reduction of nitrate to nitrite while channel two (2) represented only nitrite. The absorbance of the color product was measured by photometric detectors with 540-nm filters. This method combines high reproducibility of sample introduction via flow injection and sensitivity of spectrophotometric detection. The detection limit is 25 nM for both nitrite and nitrate. The chemistry manifolds are constructed of Teflon tubing which, along with a low- pressure Flowfit connector system, provides for low maintenance, ease of use, and high sample throughput. We demonstrated that the system can be used for the determination of both nitrate and nitrite in a variety of biological samples as well as a comparison of the results from this system and the HPLC system.
Blood Serum Cell Spectrophotometry Method comparison Lachat Multichannel

"Chemiluminescent Method For Flow Injection Analysis Of Anions"
Anal. Lett. 1986 Volume 19, Issue 23&24 Pages 2221-2230
Cooper, M.M.;Spurlin, S.R.

Abstract: The method involves displacement by analyte anions of a chemiluminescent anion bound to an ion-exchange column, followed by reaction to produce chemiluminescence. Sample solution (40 µL) was passed at 2 mL min-1 through a glass column (3 cm x 2 mm) packed with an anionic luminol derivative (prep. and characteristics given) bound to a strong anion-exchange resin. The displaced derivative then flowed to a PTFE reaction cell containing H2O2 - Fe(CN)63- solution The luminescence produced was detected with use of a photomultiplier tube mounted on the cell. Detection limits and coefficient of variation for the determination of several anions were: Cl-, 1.2 µM and 3.0%; NO2-, 1.5 µM and 3.5%; NO3-, 1.2 µM and 2.1%; Br-, 5 µM and 5.0%; and SO42-, 1.0 µM and 1.9%.
Chemiluminescence Ion exchange Resin

"A Fluorescence-based Sensor For Ammonium And Nitrate"
Anal. Lett. 1998 Volume 31, Issue 4 Pages 555-567
Satoshi Sasaki; Yoshihiro Ando; Makiko Dejima; Yoshiko Arikawa; Isao Karube

Abstract: Measurement of nitrite and nitrate in rain samples was performed using a fluorescence-based sensor. Nitrite and nitrate were reduced to ammonia using Devarda's alloy, and the gas was then passed through a membrane and reacted with o-phthaladehyde. A linear relationship between the nitrate concentration and the luminescence intensity was observed over the concentration range of 1-5 mg/l, with a relative standard deviation (RSD) of 2.3% at a nitrate concentration of 1 mg/l (n = 5). The system did not show any response toward sulfate or chloride. Results obtained from the measurement of river water samples using the sensor showed good agreement with those obtained using a conventional method.
River Rain Fluorescence Method comparison Membrane Interferences

"Flow Injection Biamperometric Determination Of Nitrite And Nitrate"
Anal. Lett. 1998 Volume 31, Issue 5 Pages 751-764
Andrei F. Danet; Vasile David

Abstract: A simple and efficient FIA method was used with good results to determine nitrite in residual waters and nitrate in natural waters. Nitrite determination is based on the reaction with iodide occurring in acidic media and biamperometric detection of the formed iodine at 2 Pt electrodes polarized at 100 mV. Nitrate is similarly determined after its previous reduction to nitrite in a Cd column. The method does not need the solution deaeration. However, the calibration graphs present 2 regions of linearity owing to the catalytic effect of the dissolved O on the iodide oxidation by nitrite.
Environmental Biamperometry Electrode Reduction column Interferences

"A Serial Array Of ISE For Use In A Portable Battery-powered Flow Injection Analyser"
Electroanalysis 1996 Volume 8, Issue 5 Pages 438-442
Telis Dimitrakopoulos, Peter W. Alexander *, D. Brynn Hibbert

Abstract: Natural water samples (200 µL) were injected into a carrier stream of either 50 mM MgSO4, 1 mM CaCl2 or 7 mM lithium acetate (6.8 ml/min) of a flow injection potentiometric system and the K, Na and nitrate ions were simultaneously detected using a planar ISE serial array (schematic shown; details given). Calibration data of the respective standard ion solutions treated with 1 mM CaCl2, and analytical data of the studied ions in the three carrier solutions are presented and discussed. The method was applied to the analysis of two natural mineral water samples (details given). Results were in good agreement with those obtained by the standard AAS method.
Mineral Environmental Electrode Electrode Electrode Potentiometry Portable Method comparison

"A Six Sensor Array Of Coated-wire Electrodes For Use In A Portable Flow Injection Analyzer"
Electroanalysis 1998 Volume 10, Issue 10 Pages 707-712
Peter W. Alexander*, Telis Dimitrakopoulos, D. Brynn Hibbert

Abstract: An array of 5 photo-cured epoxydiacrylate membrane electrodes incorporating ionophores and a Ag/AgCl wire electrode used as a chloride sensor were all used simultaneously in a previously reported multielectrode flow cell and in a portable flow injection analyzer described by P. Alexander et al. (1996). Photo-cured coated-wire electrodes for NH4+, Ca2+, H+ (pH), NO3-, and K+ and Ag/AgCl wire-based chloride electrode were developed for remote-site monitoring. The photo-cured membranes prepared exhibited strong adhesion to the metal substrate and showed improved mech. strength compared to PVC-based membranes. Each sensor in the present electrode-array exhibited near-Nernstian response over a log-linear range from 0.1-10 mM with detection limits of 0.01 mM in the flow injection potentiometric mode. The flow injection cell was capable of determining the respectively. ions in various water samples and the results were in good agreement with comparative anal. methods.
Water Electrode Electrode Electrode Potentiometry Method comparison

"Ion Chromatography Of Inorganic Anions With Potentiometric Detection Using A Metallic Copper Electrode"
J. Chromatogr. A 1985 Volume 321, Issue 1 Pages 363-374
P. R. Haddad andP. W. Alexander, M. Trojanowicz

Abstract: The determination of inorganic anions by ion chromatography with potentiometric detection using a metallic copper indicator electrode is described. The electrode response to inorganic anions can result from consumption of cuprous and cupric ions in the diffusion layer at the electrode surface, from production of copper ions due to oxidation of metallic copper, or as a result of displacement of a copper-complexing ligand from the eluent by an eluted non-complexing inorganic anion. The first possibility is exemplified by the determination of cyanide, chloride, bromide, iodide and thiocyanate, whereas the second possibility is illustrated by the determination of iodate, bromate and chlorate. An example of the indirect detection method is the determination of nitrite, nitrate and sulphate, using sodium tartrate as eluent. Calibration data for all of the above detection methods are provided and are interpreted in terms of theoretical response equations. Detection limits are also presented and are shown to be strongly dependent on the chromatographic conditions used and on the electrode response mechanism applicable to each anion.
HPIC Electrode Electrode Potentiometry

"Investigation Of Ion Transfer Across The Membrane-stabilized Interface Of Two Immiscible Electrolyte Solutions. 2. Analytical Application"
J. Electroanal. Chem. 1989 Volume 266, Issue 1 Pages 133-141
Bernd Hundhammer and Stefan Wilke

Abstract: A flow injection arrangement (to simulate ion chromatography conditions) with a wall-jet electrochemical detector is described. The detector cell (illustrated) incorporates a hydrophobic poly(ethylene terephthalate) membrane to separate the aqueous and organic phases. The stainless-steel jet inlet into the aqueous phase (containing 7.5 mM LiH2PO4 or 5 mM Na2SO4 as supporting electrolyte, with the same electrolyte in the carrier solution) acts as the counter-electrode. A SCE and a Ag - AgCl electrode are used as reference electrodes in the aqueous and organic phases, respectively. The organic phase comprises a 10 mM solution of µ-nitridobis(triphenylphosphorus)-3,3-comobis(undecahydro-1,2-dicarba-3-cobalta-closo-dodecaborate) in nitrobenzene saturated with water. A four-electrode potentiostat is used to control the p.d. across the interface. The detector has been used for the amperometric determination of anions, e.g., ClO4- NO3- and Br-, with detection limits of ~0.5 µM; cations, e.g., K+, could be determined by facilitated transfer by incorporating a neutral carrier (in this instance, dibenzo-18-crown-6) in the organic phase. The selectivity could be controlled by adjusting the p.d. across the aqueous - organic interface.
HPIC Amperometry Electrode Sample preparation Organic phase detection Crown ether Membrane Extraction

"Nitrate Sensor System For Continuous-flow Monitoring"
Sens. Actuat. B 1994 Volume 19, Issue 1-3 Pages 362-364
Otto Wassmus and Karl Cammann

Abstract: An 80 µm thick PVC-nitrate selective membrane, (cf. J. Sander, Thesis, University of Munster, 1991) was mounted on a Polyamid miniaturized body with a Ag tube internal reference covered with AgCl. The electrode was mounted within a purpose-constructed perspex flow-cell, together with a Ag/AgCl external reference electrode filled with AgCl saturated 3 M KCl. Both the working and reference electrodes were arranged perpendicular to the flow-through channel, of volume 20 µL. Calibration graphs of standard nitrate pumped through the cell at about 0.2 ml/min were linear for 0.01-10 mM nitrate with a detection limit of 3.6 µM. Higher chloride concentrations interfered with the sensor performance; interference from sulfate was negligible. The sensor system was used for environmental monitoring of ground water and water plants. Sensor lifetime was better than 6 months.
Ground Environmental Electrode Electrode Sensor Interferences

"Analysis Of Nitrite, Nitrate, And Nitric Oxide Synthase Activity In Brain Tissue By Automated Flow Injection Technique"
Methods Enzymol. 1996 Volume 268, Issue 1 Pages 152-159
Isao Yokoi, Hitoshi Habu, Hideaki Kabuto and Akitane Mori

Abstract: Automated flow injection analyzers of nitrite and nitrate (NOx) are widely used in the detection of environmental pollution. The principle of this method is dependent on Griess reaction for diazonium ion. This chapter describes an automated flow injection technique for nitrite and nitrate analysis in the brain and its application for determination of NOS activity in the brain.
Brain

"Primaquine Phosphate As A Promising Substitute For N-(1-naphthyl)ethylenediamine. 1. Determination Of Nitrate In Natural Waters In Egypt"
Anal. Sci. 1992 Volume 8, Issue 1 Pages 71-75
M. E-S. METWALLY and F. F. BELAL

Abstract: A sensitive, selective and rapid colorimetric method was developed for the determination of nitrate in natural water samples, based on coupling primaquine phosphate (PP) with diazotized p-nitroaniline (PNA) or with diazotized p-aminobenzophenone (PABP) in acid medium. The orange color produced with both amines was stable for more than 24 h, and had an absorption maximum at 484 nm, and 482 for PNA and PABP, respectively. The calibration graph was linear in the concentration range of 0.025-1.25 ppm of nitrate, with a minimum detection limit of 0.015 ppm. The molar adsorptivities were 8 x 104 mol-1 cm-1 and 7.11 x 104 mol-1 cm-1 for PNA and PABP, respectively. Heavy metals did not interfere and the interference from reducing anions was eliminated by precipitation as insoluble lead salts. The excess lead ions did not interfere. Because PP is less liable to self-diazotization-coupling reaction than N-(1 naphthyl)ethylenediamine, the method could be adopted for automated flow injection analysis of nitrate. The coupling agent used is safe; a promising substitute for the Bratton-Marshal reagent which was reported to be carcinogenic.
Environmental Spectrophotometry Interferences

"Spectrophotometric Flow Injection Techniques For Process Monitoring"
Anal. Proc. 1989 Volume 26, Issue 11 Pages 385-387
Richard L. Benson, Paul J. Worsfold, Frank W. Sweeting

Abstract: The robust, low-cost analyzer. described for automated water quality monitoring (described) incorporates a solid-state double-beam photometer with both sample and reference flow cells constructed from the same PTFE tubing (diameter 0.8 mm), as used in the rest of the flow manifold. Maximum sensitivity is achieved in the visible and near-IR regions; the red and green bands (635 and 565 nm, respectively) of the light-emitting diode sources are those most commonly used. A sampling unit and data transmission facilities are also included, as well as a supply of reagents for two week's unattended operation. The monitor was field-tested for the determination of NO3- by reduction (by copperized Cd) to NO2- and conventional azo-dye formation. The rectilinear range was 1.5 to 12.0 mg L-1 of nitrate-N, and the precis
Environmental Spectrophotometry Automation Reduction column Dual detection Precision Light emitting diode Process monitoring Low cost

"Flow Injection Determination Of Nitrate In Estuarine And Coastal Waters"
Anal. Proc. 1994 Volume 31, Issue 3 Pages 81-83
Trevor McCormack, Anthony R. J. David, Paul J. Worsfold and Robin Howland

Abstract: Water (260 µL) was injected into a NaCl stream (0.23 ml/min), merged with an NH4Cl carrier stream (0.23 ml/min) and mixed thoroughly in a column (2 cm x 3 mm i.d.) packed with glass beads (1.5-2 mm o.d.). After mixing, the stream passed through a Cd reactor column and was merged with the color reagent stream (0.16 ml/min) composed of N-(1-naphthyl)ethylenediamine dihydrochloride/sulfanilamide in a reaction coil (200 cm). The resulting pink-purple color was detected spectrophotometrically at 540 nm. The FIA manifold is shown schematically. The calibration graph was linear from 0.1 (detection limit) to 73 µM-nitrate. For higher nitrate concentrations, as occur in terrestrial discharges, the range can be extended up to 730 µM-nitrate by the use of a 50 µL sample loop. The RSD (n = 6) were 1.6 and 2% for 73 and 1 µM-nitrate, respectively.
Estuarine Sea Spectrophotometry Glass beads

"Flow Injection Analysis For Seawater Micronutrients"
Adv. Chem. Ser. 1985 Volume 209, Issue 1 Pages 7-30
Kenneth S. Johnson, Robert L. Petty, and Jens Thomsen

Abstract: Flow-injection analysis (FIA) is a technique for automating chemical analyzes. The principles of FIA are reviewed here. Methods for applying FIA to the anayses of nitrate, nitrite, phosphate, silicate, and total amino acids in seawater are examined. Analyses of other nutrients, metals, and carbonate system components are also discussed. Various techniques to eliminate the refractive index effect are reviewed. Finally, several examples of the application of FIA to oceanographic problems are presented.
Sea

"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.
Feed Food Environmental Sample preparation Spectrophotometry Simultaneous analysis

"Enhanced Ion Chromatography With Sequential Flow Injection Analysis. Determination Of Common Anions And Nitrite"
Am. Environ. Lab. 1998 Volume 10, Issue 2 Pages 6-7
Karmarkar, S.V.

Abstract: Nitrite and F-, Cl-, NO3- Br-, HPO42-, SO42- were determined in wastewater, , groundwater and surface water samples by enhanced ion chromatography with sequential flow injection anal.
Waste Ground Surface HPIC Sequential injection

"Comparison Of Flow Injection Methods For Nitrate Analysis In Aqueous Environmental Samples"
Anal. Methods Instrum. 1995 Volume 2, Issue 6 Pages 330-336
A.Cerd&agrave;, M.T.Oms, V.Cerd&agrave;, R.Forteza

Abstract: Reduction of nitrate to nitrite was carried out by means of a Cd-Cu column, by hydrazine, or by photochemical reduction. The chromogenic reagent was 0.5 g/l N-(1-naphthyl)ethylenediamine hydrochloride, 20 g/l sulfanilamide and 50 mL concentrated HCl. Nitrites were detected at 540 nm using a diode array detector. Liquids were pumped with Gilson peristaltic pumps and tubing was of PTFE (0.5 mm i.d.). The UV light source was a 15 W Hg lamp. With the Cd-Cu column, calibration was linear in the range 6-250 µM-nitrate and 2-250 µM-nitrite and detection limits were 0.5 µM-nitrate and 0.2 µM-nitrite. There was no interference from 200 ppm chromate, sulfate and carbonate, 100 ppm Ca(II), Fe(II), NI(II) and Cu(II) and 40 ppm Mg(II) and Zn(II). With hydrazine reduction, detection limits were 0.01 µM and 0.05 µM for nitrite and nitrate, respectively, with response linear up to 300 µM and 200 µM, respectively. With photochemical reduction, calibration graphs were linear in the range 1-300 µM-nitrate, and 1-400 µM (with UV radiation) and 1-200 µM (without UV radiation) for nitrite. The detection limit for nitrate was 0.12 µM.
Environmental Spectrophotometry Reduction column Interferences Method comparison Photochemistry Chromogenic reagent

"Fluorimetric Determination Of Nitrate And Nitrite"
Analusis 1995 Volume 23, Issue 7 Pages 312-319
ML Viriot, B Mahieuxe, MC Carre, JC Andre

Abstract: Fluorimetric determination of nitrate and nitrite in the last 20 years is reviewed. First, the necessity of nitrate and nitrite analysis is recalled. Second, the fluorimetric available methods are described, especially with normalization of the units for the reported data (mg/l and M (mol/l)); the major results are summarized in two tables (I and II) and in order to allow a comparison, the methods are listed according to their detection limit (tables III and IV), which is also related to the fluorescence emission wavelength through two graphs (figs 1 and 2). Third, in a critical discussion, the reported methods are briefly evaluated(chronological classification; tables V and VI). Fluorescence use as chromatographic detection for nitrate and nitrite is only mentioned. (49 references)
Environmental LC Fluorescence Review

"Determination Of Nitrate In Carbon Black By Flow Injection Analysis With Potentiometric Detection"
Analusis 1997 Volume 25, Issue 2 Pages 32-35
IG. Canal, JLFC Lima, MCBSM Montenegro, R Prez-Olmos

Abstract: H2O (100 ml) was added to 10 g C black (details given) and the mixture incubated at 100°C for 5 min. The resulting suspension was filtered and the residue washed and diluted to 100 mL with water. A 150 µL portion was injected into channel 1 of a double channel manifold containing 10 µM-sodium nitrate. The resulting solution was mixed in a 70 cm reaction tube with carrier in channel 2 which comprised sodium sulfate or a solution of 0.02 M lead acetate, 0.01 M lead monoxide, 0.02 M potassium acetate and 0.01 M sulfamic acid. A flow rate of 6.8 ml/min was used. Nitrate levels were determined by an electrode which incorporated a PVC membrane and an ionic sensor based on tris(4,7-diphenyl-1,10-phenanthroline)nickel(II) complex dissolved in 2-nitrophenyl octyl ether. The lower limit of the linear range and the limit of detection were 70 and 30 µM, respectively. Levels of nitrate in C black are reported, with recoveries and RSD of 98.8-103.4% and 0.3-3.7% (n = 3), respectively. This paper reports the potentiometric detection of nitrate in carbon black samples by flow injection analysis (FIA). The detection system used consisted of a nitrate sensitive tubular electrode without inner reference solution, incorporating a PVC membrane with an ionic sensor based on tris(4,7-diphenyl-1,10-phenantroline) nickel(II) dissolved in 2-nitrophenyloctyl ether as the solvent mediator. According to the working characteristics of the tubular electrodes, a double channel flow injection system was constructed and optimized for direct sample analysis in a reduced time-frame. A solution of Pb(CH3COO)(2), PbO, CH3COOK and NH2SO3H was used as ionic strength and pH adjuster for both samples and standards. The tubular electrodes showed a linear response for a concentration of at least 5 10^-5 mol.L-1 with a slope of 58.3±0.9 mV/decade and a reproducibility of±0.1 mV within two successive calibrations. Analysis of 10 different samples from several factories showed satisfactory results with average recoveries of about 100.5%±1.5% and a variation coefficient of 1.5%. With the proposed system, a sampling rate of 120 samples/h was obtained. (11 References)
Inorganic compound Electrode Electrode Potentiometry Detection limit

"Automated Tobacco Analysis By Means Of Flow Injection Analysis"
Beitr. Tabakforsch. Int. 1988 Volume 14, Issue 2 Pages 105-118
Finster P, Hollweg J, Kausch E, Burmester U

Abstract: The construction and mode of operation are described of a simple modular instrument for flow injection analysis. The instrument, which is suitable for multi-component analysis of small series of samples, was applied in determination of nicotine, NO3-, Cl-, NH4+ and PO43- in tobacco. Stopped-flow conditions permitted removal of background absorbance originating from the sample matrix.
Plant Sample preparation Extraction Automation Dialysis Gas diffusion Stopped-flow

"Factors Influencing The Flow Injection Analysis"
Bull. Inst. Chem. 1987 Volume 34, Issue 1 Pages 1-7
Hung, T.C.;Chuang, A.;Meng, P.J.

Abstract: The results for determinations of Cl-, NH4+, NO2-, NO3-, total N and total P in water are presented. The effects of flow rate, coil length, sample volume and temperature on accuracy were studied.
Environmental Optimization Review

"Determination Of Trace Amounts Of Nitrite And Nitrate By Flow Injection Spectrophotometry"
Bunseki Kagaku 1982 Volume 31, Issue 12 Pages 732-733
Susumu NAKASHIMA, Masakazu YAGI, Michio ZENKI, Akinori TAKAHASHI, Kyoji TOEI

Abstract: A system has been developed for the determination of nitrite and nitrate ions by flow injection analysis. The flow lines were made from polytetrafluoroethylene (PTFE) tubing. For the nitrite determination a 650 µl of sample is injected into a stream of 0.04 % (w/v) p-aminoacetophenone (p-AAP) solution in 47 mM hydrochloric acid, and flows down a mixing coil (1 mmφ x 1 m) in a thermostated bath at 45°C. The mixture meets a stream of 0.11 % (w/v) m-phenylene-diamine dihydrochloride (m-PD) solution in 1.2 mM hydrochloric acid. After the mixing coil (1 mmφ x 1 m, 45°C), the absorbance at 456 nm is measured by a spectrophotometer with a 10-mm flow-through cell (8 µl) against water as reference. For the nitrate determination a 650 µl of sample is injected into 1.2 mM EDTA carrier solution (pH 9.8) and passed through a copperized cadmium column {3 mmφ x 70 mm, particle size: (0.52) mm} to convert quantitatively nitrate to nitrite. Then, the carrier solution is merged into the stream of a mixed reagent solution of 0.02 % (w/v)p-AAP and 0.055 % (w/v) m-PD in 24 mM hydrochloric acid. After the mixing coil (1 mmφ x 1 m, 45°C), the absorbance is measured at 456 nm. Sampling rate was 30 samples per hour. The relative standard deviations (n= 10) were 0.97 % and 0.89 % for 10 µg/l and 30 µg/l of nitrite-nitrogen, respectively, and 0.95 % and 0.66 % for 0.1 mg/l and 0.3 mg/l of nitrate-nitrogen, respectively. A detection limit was 0.4 µg/l and 2 µg/l for nitrite- and nitrate-nitrogen, respectively.
Spectrophotometry Column Heated reaction Differential detection Speciation

"Spectrophotometric Determination Of Nitrate Ion Using Nitrosation/flow Injection Analysis"
Bunseki Kagaku 1987 Volume 36, Issue 3 Pages 207-209
Rui, S.C.;Motomizu, S.;Toei, K.

Abstract: Sample solution was injected into a stream of 1 mM EDTA (pH 8) and passed through a reduction column (30 cm x 2 mm) packed with copperized cadmium. The stream was then mixed with 0.8 mM NN-1,1'-phenyliminodipropan-2-ol - 0.35 M HCl - 0.15 M H3PO4 and passed through a reaction coil (2 m x 0.5 mm) at 80°C. The resulting stream was passed through a cooling coil (50 cm x 0.5 mm) before spectrophotometric detection at 500 nm. The calibration graph was rectilinear up to 0.2 mM NO3-. The limit of detection was 1 µM-NO3- and the coefficient of variation (n = 10) was 0.4%. The sampling rate was 40 h-1. Nitrate was determined by this method in river water at 10 µM level.
River Spectrophotometry Column EDTA Heated reaction Reduction column

"Application Of Flow Injection Analysis Method To Water Quality Analysis"
Bunseki 1987 Volume 36, Issue 4 Pages 245-252
Korenaga, T.

Abstract: A review is presented, covering the period from 1982 to 1986. The dissolved components, e.g., metal ions, N compounds, P compounds and anions, determined by flow injection are tabulated. (156 references).
Water Review Silica

"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.
Environmental Spectrophotometry Valve Glass Column Heated reaction Teflon membrane

"Simultaneous Determination Of Nitrate And Nitrite Ion By Micro-flow Injection Analysis"
Bunseki Kagaku 1998 Volume 47, Issue 6 Pages 375-380
Lan Ma, Mitsuko Oshima, Shoji Motomizu and Takayasu Hattori

Abstract: To minimize the ample size, reagent consumption and waste, a micro-flow injection analysis (µFIA) was investigated and applied to the simultaneous determination of NO3- and NO2- in water samples. The NO3- was reduced to NO2- with reduction efficiency 99% on line by passing through a mini column (0.53 mm i.d. x 5 cm) packed with 60-80-mesh powd. Cd/Cu, and was detected at 538 nm. The carrier solution contained EDTA and NaCl (pH 8.1-8.4) and the reagent solution contained sulfanilamide, N-(1-naphthyl)ethylenediamine, and HCl. The carrier stream was split into 2 streams, and one of them passed through the mini column to give a peak derived from NO3- and NO2-, and the other stream passed through a bypass column packed with glass beads to give a peak derived from NO2-. The detection limit of NO3- and NO2- were ~1 x 10^-7 M.
River Spectrophotometry Microfluidic Reduction column Reagent consumption Simultaneous analysis Sample splitting

"Direct Potentiometric Measure Of The Fluoride, Chloride, Cyanide, Sulfide, Nitrate, And Ammonium Ions In Waters And Waste Waters"
Chem. Tech. 1975 Volume 4, Issue 5 Pages 183-188
Oehme, Friedrich

Abstract: Photometric and direct potentiometric methods for the determination of the more important ions present in waters and effluents are compared, and the fundamentals and possibilities of potentiometric ion measurements are reviewed. The construction, suitablity, stability, reproducibility, and selectivity of ion-sensitive electrodes used in continuous measuring application are discussed. 28 references (SFS)
Water Potentiometry Apparatus Detector

"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.
Environmental Electrode 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.
Environmental Sample preparation Spectrophotometry Reverse

"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.
Environmental Reflectometry Method comparison

"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.
Environmental Sample preparation Lachat

"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.
Environmental Environmental Spectrophotometry Automation Review Merging zones

"Flow Injection Analysis. Spektrofotometrisk Bestemmelse Af Chlorid, Nitrit Og Nitrat"
Dan. Eng. Acad. 1981 Volume 53, Issue NA Pages 78-NA
Hansen, J.H.B.

Abstract: NA
Spectrophotometry

"New Technique For Determination Of Nitrate And Nitrite In Water"
Eau Ind. Nuisances 1983 Volume 75, Issue 1 Pages 64-66
Lerique, D.;Ughetto, L.

Abstract: Nitrite is determined by the sulfanilamide - N-1-naphthylethylenediamine reaction, with colorimetric measurement at 540 nm; NO3- are determined as NO2- after reduction by cadmium. The analyzer. developed incorporates independent peristaltic pumps for each of the four analysis channels, a precise injection system and aspecially designed replaceable manifold, and is controlled by a microprocessor; 300 samples can be analyzed in 1 h. The sample is injected into a non-segmented stream of reagent; residence time for samples is reproducible and dispersion is controlled.
Environmental Spectrophotometry Computer

"Continuous-flow Method For Simultaneous Determination Of Nitrate And Ammonia In Water"
Environ. Sci. Technol. 1986 Volume 20, Issue 5 Pages 515-517
Toyoaki Aoki, Satoshi Uemura, and Makoto Munemori

Abstract: River water was analyzed by continuous-flow analysis. The sample was mixed with 0.3% sulfanilic acid solution, 7 M NaOH and TiCl3 solution, and the NH3 present in the sample or produced by the reduction of NO3- permeated through a micro-porous PTFE membrane into a buffer solution containing phthalaldehyde - 2-mercaptoethanol. The fluorescence of the buffer solution was then measured at 486 nm (excitation at 370 nm); the original NH3 content was determined as above but without the reduction of the NO3-. The calibration graphs for NO3- and NH3 were rectilinear for 0.5 µM to 0.2 mM and 0.2 µM to 0.2 mM, respectively, and the corresponding detection limits were 0.18 µM and 0.018 µM. The coefficient of variation were 3.3 and 4.4% for NO3- and NH3, respectively. Interference due to methylamine and ethylamine was reduced by lowering the pH of the reaction solution
River Fluorescence Gas diffusion Interferences Microporous membrane Teflon membrane

"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.
Environmental Environmental Sample preparation Spectrophotometry Simultaneous analysis Speciation Differential detection

"Flow Injection Determination Of Trace Nitrite By Amperometric Detection. Photochemical Reaction System Of Nitrite - Iodine - Ethylenediaminetetraacetic Acid"
Fenxi Huaxue 1991 Volume 19, Issue 9 Pages 1040-1042
Liu, R.M.;Liu, D.J.

Abstract: Flow injection kinetic determination of trace amounts of nitrite based on its inhibitory effect on the photochemical reaction between iodine and EDTA was developed by using a self-made flow-through photochemical reactor (power 60 W and length 45 cm) and an amperometric detector equipped with a flow-cell (illustrated). Optimum conditions were established. A platinum indicator electrode and a SCE were used for amperometric detection, a constant potential of 100 mV was applied, 0.5 M iodine, 1.5 mM EDTA and acetate buffer solution (pH 7) were mixed in the reaction cell. The calibration graph was rectilinear from 0.1 to 4 µmM-NO2-. For the determination of NO2- in natural water, recoveries were 91 to 106% and the coefficient of variation (n = 6) was 3.4%. Interference by 23 ions in the cited determination was investigated.
Environmental Amperometry Electrode Buffer Interferences Kinetic Reactor

"Study Of Online Chloride Removal By A Pre-column Connected With Low-pressure Ion Chromatography And Its Application"
Fenxi Huaxue 1995 Volume 23, Issue 1 Pages 86-88
Liang, L.L.;Wu, Q.F.;Guo, X.H.;Chen, Y.B.

Abstract: Sample (40 l) was loaded at 1 ml/min into a home-made online chloride removal precolumn (36 x 6 mm i.d.) of anion-exchange resin and 0.1 M AgNO3, as a flow system for clean up then through a separation column with 1.2 mM sodium carbonate/2.4 mM sodium hydrogen carbonate as eluent to separate fluoride, nitrite, nitrate and sulfate and a suppression column prior to detection with a conductivity detector operating at 500 and between -1 and 4 mV. Detection limits for fluoride, nitrite, nitrate and sulfate were 0.85, 0.62, 0.65 and 0.92 mg/l, respectively. The system was applied to the analysis of sea water and ground water.
Sea HPIC Column

"Application Of A Photochemical Reaction In A Flow Injection System. 5. Determination Of Trace Amounts Of Nitrite With A Nitrate/luminol Photochemical Reaction System"
Fenxi Huaxue 1995 Volume 23, Issue 3 Pages 321-324
Liu, D.J.;Liu, R.M.;Sun, A.L.;Liu, G.H.

Abstract: Sample was adjusted to pH 5 and injected into a carrier stream of H2SO4 (1.5 ml/min) to mix in a photochemical reactor (180 cm) while irradiated with a high-pressure Hg lamp. It was then carried via a connection tube (11 cm) to react with a stream of 50 µM-luminol containing 0.1 M KOH of pH 13 (0.5 ml/min) in a reactor (3 cm) and the chemiluminescence intensity was measured. The calibration graph was linear for 50 nM- to 0.1 mM nitrate and the RSD were 0.74-0.92%. Fe(III), Cu(II), Co(II) and Ni(II) interfered seriously. The method was applied to river and well water and the results were compared with those obtained by the phenol disulfonic acid method.
Well River Chemiluminescence Photochemistry Interferences Method comparison

"A Gravitational Phase Separator For Use In Flow Injection Liquid-liquid Extraction-indirect Atomic Absorption-spectrophotometric Determination Of Nitrate And Nitrite"
Fenxi Huaxue 1997 Volume 25, Issue 1 Pages 72-75
Qiu, H.O.;Shuai, Q.;Tang, Z.Y.;Lin, S.L.

Abstract: After treatment with Ce(IV) and pH adjustment to ~4, a 200 µL nitrate and nitrite mixture was injected via a FIA manifold equipped with a phase separator for extraction (diagram shown) into a carrier stream comprising 0.25 M KH2PO4 buffer of pH 4.5, 0.15 M hydroxylamine sulfate, 2.5 ml/l Cu(II) solution and water. The solution was reacted with 1.2 mM neocuproine in IBMK and the resulting ion pair formed was extracted for AAS determination of total nitrate and nitrite. For determination of nitrate, the nitrite was destroyed by sulfamic acid before carrying out the above procedure. Both main and auxiliary pumps were used at selected flow-rates, such as 2 ml/min. The pre-concentration factor was 26. The detection limit for nitrate was 28 µg/l. The RSD (n = 10) were The sampling frequency was 25 runs/h. The method was used to analyze pond water; recoveries ranged from 100-110%.
Pond Spectrophotometry Sample preparation Phase separator MIBK Ion pair extraction Speciation Preconcentration Indirect

"FIAstar For Routine Analysis In A Water Laboratory"
FIAstar Newsletter 1985 Volume 1, Issue 1 Pages 1-NA
Hansson, R.;Dahlback, J.

Abstract: NA
Water Spectrophotometry Tecator

"Determination Of Nitrite, Nitrate, Phosphate, Sulfate And Ammonia By Flow Injection Analysis And Manual Standard Methods"
FIAstar Newsletter 1986 Volume 4, Issue 1 Pages 2-NA
Koch, B.;Moller, R.

Abstract: NA
Water Spectrophotometry Method comparison Tecator Standard method

"Determination Of Nitrate And Nitrite In Milk And Milk Products By Flow Injection Analysis"
FIAstar Newsletter 1987 Volume 6, Issue 1 Pages 1-NA
Munksgaard, L.L.;Thymark, L.

Abstract: NA
Milk Milk Product Spectrophotometry Tecator

"Analysis Of Anions And Cations In Drinking Water Samples By Capillary Ion Analysis"
Food Chem. 1998 Volume 61, Issue 1-2 Pages 249-254
Bahruddin Saad*, Fen Wei Pok, Amat Ngilmi Ahmad Sujari and Muhammad Idiris Saleh

Abstract: The use of capillary ion electrophoresis (CIE, Waters' tradename: Capillary Ion Analysis, CIA) for the analysis of four anions and four cations in drinking water samples available on the Malaysian market, such as natural mineral water, bottled drinking water and tap water, was investigated. In addition, zam-zam water (an underground water, much sought-after by Muslims and only available in Mekah, Saudi Arabia) was also analyzed. The anions analyzed were chloride, sulfate, nitrate and fluoride while the cations analyzed were potassium, calcium, sodium and magnesium. Results of this determination generally show a low content of anions and high content of calcium and magnesium in natural mineral water and non-detectable amounts of anions and cations in bottled drinking water. Out of the 15 mineral waters of different brands that were analyzed, four brands show anionic and cationic levels almost similar to that of tap water. With the exception of fluoride, an abnormally high level of both anions and cations were detected in all the zam-zam water samples analyzed, as compared to the other drinking waters.
Water Mineral Electrophoresis

"FIA Evaluation Of Nitrite And Nitrate Contents Of Liver Pates"
Food Chem. 1998 Volume 62, Issue 3 Pages 359-362
Ol&iacute;via Pinho, Isabel M. P. L. V. O. Ferreira, M. Beatriz P. P. Oliveira and Margarida A. Ferreira

Abstract: A comparative study on the nitrite and nitrate contents of 15 liver pate brands, in a total of 45 samples (three batches per brand) is presented. The study was conducted on two different kind of pates: pork liver pates and fowl liver pates. For the simultaneous determination of nitrite and nitrate, an automated flow injection system with spectrophotometric detection was used. The manifold was based on the splitting of the flow after injection and subsequent confluence of the flow before reaching the detector, allowing the reduction of nitrate to nitrite in part of the sample plug on an online copper cadmium reductor column. Spectrophotometric determination was made after a diazotization coupling reaction. The levels of nitrites and nitrates ranged from 1.07 mg NaNO2 kg-1 ± 0.43 to 15.9 mg NaNO2 kg-1 ± 5.2 and from 24.5 mg NaNO3 kg-1 ± 2.7 to 207 mg NaNO3 kg-1 ± 14, respectively. The levels of concentration. of these constituents were below the allowable limits. A significant dispersion in the results was observed between different brands and within some of the brands.
Liver Spectrophotometry Simultaneous analysis Reduction column Sample splitting

"Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate In Environmental Water And Vegetable By Flow Injection Analysis"
Huanjing Kexue 1998 Volume 19, Issue 3 Pages 84-86
Gao Loujun, Zhang Zhiqi

Abstract: A flow injection spectrophotometry is proposed for simultaneous determination of NO2- and NO3- in environmental waters and vegetables based on the N-(1-naphthyl)ethylenediamine spectrophotometry. A technique of double zone injection and reduction column of Cd plated Zn power zone isolation was adopted. The range of determination was 0.01-2.0 µg/mL for NO2--N and 0.05-5.0 µg/mL for NO3--N, sampling rate 30 samples per h.
Environmental Vegetable Spectrophotometry Simultaneous analysis Merging zones Reduction column

"Automated Measuring System For Biological Wastewater Treatment Plant With Biological Removal Of Phosphate"
IFAC Proc. Ser. 1986 Volume 4, Issue 1 Pages 131-136
Pedersen, K. M.; Haagensen, P.; Kuemmel, M.; Soeeberg, H. (SFS)

Abstract: An automated method for the monitoring of concentrations of PO43-, NO3-, and NH4+ in effluents from biological wastewater treatment plants is based on flow injection with sampling by dialysis. (SFS)
Biological Waste Automation Dialysis

"Experience With Flow Injection Analysis In Limnological Research"
InFocus 1987 Volume 10, Issue 1 Pages 8-NA
Ripl, W.;Michel, J.

Abstract: NA
Sea Spectrophotometry Tecator

"A Converging Wall-jet Instrument For Ion Selective Electrode Dynamic Response Studies"
Instrum. Sci. Technol. 1998 Volume 26, Issue 5 Pages 461-472
Michael L. Clay; Russell E. Pierce; Vaneica Y. Young; Steve Hoke

Abstract: Ion selective electrodes are used to conduct real-time measurements of gaseous thermal degradation products from halon replacement experiments. Response characteristics of these ion selective electrodes are needed to address potential interferences and surface poisoning experienced under field conditions. The design and the fabrication of an in situ, converging wall-jet instrument for the measurement of the dynamic responses of ion selective electrodes are described. Various time delays associated with the generation and detection of ion activity steps have been quantitatively determined. Dynamic response measurements for iodide steps on a Corning iodide/cyanide ion selective electrode are comparable to those obtained on the best of the earlier instrument designs, the in situ, switched wall-jet instrument. The advantages of the converging wall-jet instrument over the switched wall-jet instrument are identified.
Electrode

"Sulfur And Nutrient Analysis Of Sediments And Sediment Interstitial Water"
Int. J. Environ. Anal. Chem. 1988 Volume 34, Issue 2 Pages 109-117
Ripl, W.;Michel, J.

Abstract: An analytical system is described for determination of S, PO43- and NO3- in sediments and water. The system includes sampling, sample pre-treatment and digestion and flow injection analysis by standard and previously described methods. For the determination of SO42-, the calibration graph was rectilinear from 10 to 40 mg L-1 with coefficient of variation of 2.5%. Results are presented for PO43- and NO3- determined in interstitial water.
Environmental Interstitial Sample preparation

"Automatic System For Simultaneous Determination Of Nitrates And Nitrites In Waters"
Int. J. Environ. Anal. Chem. 1989 Volume 35, Issue 3 Pages 161-167
J. Maim&oacute;; A. Cladera; F. Mas; R. Forteza; J. M. Estela a; V. Cerd&aacute;

Abstract: In the flow injection analysis system described, the sample is split into two streams, one of which is directly treated with azo-dye reagent and passed to the sample flow cell of a double-beam spectrophotometer where the absorbance due to NO2- is measured. The other stream passes through a reduction micro-column (6 cm x 1 mm) of copperized cadmium where NO3- is reduced to NO2-. The sample is then treated with the azo-dye reagent, and the overall mixture is passed to the reference cell of the spectrophotometer where the abosrbance due to the sum of NO2- and NO3- is measured; NO3- is determined from the difference in absorbance values. The calibration graphs were rectilinear for 10 to 200 mM NO3- and 2.5 to 50 µmM-NO2-, respectively. The technique has been automated by connecting a digital potentiometer, used as a data-acquisition interface for an Amstrad 128 microcomputer, to the register output of the spectrophotometer. Software for data storage and processing is described. Up to 60 samples per hour can be analyzed. In the flow injection analysis system described, the sample is split into two streams, one of which is directly treated with azo-dye reagent and passed to the sample flow cell of a double-beam spectrophotometer where the absorbance due to NO2- is measured. The other stream passes through a reduction micro-column (6 cm x 1 mm) of copperized cadmium where NO3- is reduced to NO2-. The sample is then treated with the azo-dye reagent, and the overall mixture is passed to the reference cell of the spectrophotometer where the abosrbance due to the sum of NO2- and NO3- is measured; NO3- is determined from the difference in absorbance values. The calibration graphs were rectilinear for 10 to 200 mM NO3- and 2.5 to 50 µmM-NO2-, respectively. The technique has been automated by connecting a digital potentiometer, used as a data-acquisition interface for an Amstrad 128 microcomputer, to the register output of the spectrophotometer. Software for data storage and processing is described. Up to 60 samples per hour can be analyzed.
Environmental Spectrophotometry Potentiometry Automation Column Calibration

"Determination Of Nitrate In The Presence Of Nitrite In Natural Waters By Flow Injection Analysis With A Non-quantitative Online Cadmium Reductor"
Int. J. Environ. Anal. Chem. 1994 Volume 57, Issue 4 Pages 263-277
S. -C. Pai; J. P. Riley

Abstract: Several analytical problems in the determination of nitrate using flow injection analysis (FIA) coupled with an on-line Cd reductor have been studied. It was found difficult to prepare a nearly 100%-efficient copperized Cd reductor which maintains its efficiency over a lengthy period. Instead, the use of a narrow and lower efficiency Cd coil is recommended because it is more stable and therefore more suitable for FIA. Since the conversion of nitrate to nitrite is not quantitative, results for nitrate tend to be over-estimates when nitrite is also present. This problem has been solved by using a simple correction scheme to compensate for the effect of nitrite, thus enabling the correct nitrate concentration to be evaluated. The validity of the correction procedure has been confirmed by running a series of known standards containing both nitrate and nitrite with three types of FIA manifolds. Results for nitrate were accurate for fresh and saline waters even when the co-existing nitrite concentrations were high.
River Sea Spectrophotometry Interferences Reduction column Manifold comparison

"New Approach For Determining Low Level Nutrients In Saline, Brackish And Fresh Water Samples"
Int. Labmate 1993 Volume 18, Issue 1 Pages 7-9
Ranger, C.;Diamond, D.

Abstract: A description is given of the hardware, software and chemistry involved in the QuikChem AE system (Lachat Instruments, Milwaukee, WI, USA) developed for determining low level nutrients in water samples of 0 to 35 ppt salinity. The system consists of a multi-channel continuous-flow analyzer. which uses the FIA technique and a color reaction which is detected photometrically. The system gives negligible interference from refractive index and salt effects and the use of ultra pure water for standards, carrier and blanks mean there is no need to obtain nutrient depleted seawater for preparing standards. The ranges or detection limits were 0.049 µM-NH3, 0.017 µM-nitrate, 0.025 µM-phosphate and 0.048 µM-silicate.
Sea Brackish River Spectrophotometry Multichannel Lachat Refractive index Interferences

"Flow Injection Determination Of Nitrate In Vegetables Using A Tubular Potentiometric Detector"
J. Agric. Food Chem. 1995 Volume 43, Issue 3 Pages 704-707
Jose L. F. C. Lima, Antonio O. S. S. Rangel, and M. Renata S. Souto

Abstract: Dried powdered vegetable was extracted by the method of Mitrakas and Alexiades (Mikrochim. Acta, 1990, 1, 7) and the extract was injected into a carrier stream (6 ml/min) of 1 µM-KNO3 in extractant solution (10 nM-lead acetate, 5 mM lead oxide and 10 mM sodium acetate) in a low dispersion FIA system. The flow passed through a tubular nitrate ISE with (4,7-diphenylphenanthroline) nickel(II) dissolved in o-nitrophenyl octyl ether immobilized in a PVC membrane and without an inner reference solution (preparation details given). The calibration graph was linear for 0.4-40 mM nitrate with a detection limit of 28 µM. Recoveries were 93.8-104% for nitrate in parsley, lettuce and spinach with RSD of 3%. A flow injection system with potentiometric detection for the determination of nitrate in vegetables was developed. For this purpose a tubular nitrate ion-selective electrode with the ion-exchanger system [(4,7- diphenylphenanthroline)nickel(II) dissolved in o-nitrophenyl octyl ether] immobilized in a PVC membrane and without inner reference solution was prepared. The flow injection manifold incorporating the tubular electrode was used for the determination of nitrate in vegetables (lettuce, parsley, and spinach), using a mixture of lead acetate, lead oxide, and sodium acetate as nitrate extractant, ionic strength adjustor, and interference suppressor solution. The quality of the results obtained by the proposed methodology was assessed by comparing them with those provided by a conventional potentiometric methodology and also through recovery tests (recoveries from 94 to 104% were found). A sampling rate of 120 samples per hour was achieved with a relative standards deviation lower than 2%.
Parsley Vegetable Vegetable Electrode Electrode Potentiometry Electrode Method comparison Interferences

"Novel Approach To Non-segmented Flow Analysis. 3. Nitrate, Nitrite And Ammonium In Waters"
J. Autom. Methods Manag. Chem. 1988 Volume 10, Issue 4 Pages 192-197
D. J. MALCOLME-LAWES and C. PASQUINI

Abstract: Some modifications to the system described in Part II (Anal. Abstr., 1988, 50, 9J17) are discussed. The system is illustrated schematically. For determination of NO2-, the reagent solution comprised 10 g L-1 of sulfanilamide, 0.8 g L-1 of N-naphthylethylenediamine hydrochloride and 10 mL L-1 of concentrated HCl, the carrier solution was water containing 15 g L-1 of NaCl and 10 mL L-1 of concentrated HCl, the reaction coil was maintained at 50°C, the reaction time was 12 s and detection was at 545 nm. The calibration graph was rectilinear for up to 100 ppb of NO2-. Nitrate was determined by diverting the sample via the Cd reducing column and determining the NO2- produced as described above. The calibration graph was rectilinear for up to 50 ppm of NO3-. For determination of NH4+, three reagent solution were used, viz, 0.5% phenol (w/v) containing 0.5% of sodium nitroprusside, 0.15% NaClO and 0.35 M NaOH containing 1.5% of Na2EDTA, the carrier solution was aqueous 0.05 M NaOH containing 15 g L-1 of NaCl, the reaction coil was maintained at 50°C, the reaction time was 12 s, and detection was at 690 nm. The calibration graph was rectilinear for up to 120 ppb of NH4+. The instrument could be programmed to carry out sequential determination of NO2-, NO3- and NH4+ in water. The limits of detection were 5, 30 and 4 ppb for NH4+, NO3- and NO2-, respectively.
Environmental Spectrophotometry Heated reaction Reduction column

"Sequential Automatic Online Determination Of Aquiculture Nutrients: Phosphate And Nitrate"
J. Autom. Methods Manag. Chem. 1992 Volume 14, Issue 5 Pages 173-175
P. LINARES, M. D. LUQUE DE CASTRO, and M. VALC&Aacute;RCEL

Abstract: A method was devised for single-channel continuous-flow analysis of NO3- and PO43- in waters with use of a programmable switching valve. For PO43- the reagent was 5% molybdate - 2% ascorbic acid in 2 M HNO3 - glycerol (9:1) and for NO3- the reagent was 0.38% sulfanilamide - 0.144% N-1-naphthylethylenediamine in 4% HCl containing 1.6% NaCl. Rectilinear calibration ranges were 5 to 100 µg mL-1 for NO3- and 1 to 20 µg mL-1 for PO43- and operational ratios of NO3- to PO43- were 1:4 to 100:1 with sampling at up to 45 h-1. The method has been applied to fish-farm seawater.
Water Sea Spectrophotometry Valve Automation

"Flow Injection Analysis For Online Monitoring Of Nutrients In Aquaculture"
J. Autom. Methods Manag. Chem. 1992 Volume 14, Issue 5 Pages 181-183
A. C. ARIZA, P. LINARES, M. D. LUQUE DE CASTRO, and M. VALC&Aacute;RCEL

Abstract: Automated normal and reversed flow injection - spectrophotometric methods are described for use in monitoring NH3 and NO2- in tank input and outlet streams at fish hatcheries. The methods are suitable for sampling at up to 40 h-1. Schematic diagrams and operating parameters are given. Rectilinear calibration ranges are 0.5 to 8.5 µg mL-1 (normal) and 0.1 to 2.0 µg mL-1 (reversed) for NO3- and 5 to 80 µg mL-1 (normal) for NH3, with respective coefficient of variation of 3.5, 1.0 and 1.0%. Tolerances of several foreign ions are tabulated. NH3 and NO2- were determined in seawater by photometric flow
Sea Spectrophotometry Reverse Interferences

"Portable Battery-powered Flow Injection Monitor For The In Situ Analysis Of Nitrate In Natural Waters"
J. Autom. Methods Manag. Chem. 1993 Volume 15, Issue 5 Pages 159-166
N. J. BLUNDELL, A. HOPKINS, P. J. WORSFOLD, and H. CASEY

Abstract: A solid state photometric detector is described comprising a light emitting diode as the light source and a photodiode or phototransistor as the detector. The signal output was amplified, converted by an analogue-to-digital converter and processed by a microcomputer. The system was used as the detector in a FIA system. The sample (30 µL) was injected onto a 1% ammonium chloride carrier stream (0.7 ml/min) and reduced on a copperized cadmium column (4 cm x 3 mm i.d.). The stream was then merged with a stream (0.7 ml/min) consisting of 0.05% N-(1-naphthyl)ethylenediamine dihydrochloride/2.5% sulfanilamide (1:1) in 10% H3PO4. The mixed stream was passed through a PTFE reaction column (200 cm x 0.8 mm i.d.) and into a flow cell for detection at 565 nm. Calibration graphs were linear up to 12 mg/l of nitrate with a detection limit of 50 µg/l.
Environmental Spectrophotometry Portable Light emitting diode Photodiode

"Indirect Atomic Absorption Spectrophotometric Method For The Determination Of Nitrate"
J. Chem. Soc. Pak. 1985 Volume 7, Issue 3 Pages 209-213
Anwar, Jamil; Tanveer ul Haque (SFS)

Abstract: An indirect atomic absorption spectrophotometric method for the determination of 0.5-5 mmol NO3- is described. The method is based on the formation of the insoluble ternary complex, [Ag(Phen)2]NO3 (Phen = 1,10-phenanthroline) by adding an excess of [Ag(Phen)2]+ solution to the NO3- sample. The absorbance of the unreacted silver ions was measured in an air-C2H2 flame. The effect of various ions was investigated. The method is successfully employed for the determination of NO3- in fertilizer samples.
Commercial product Spectrophotometry Indirect Interferences Complexation

"Spectrophotometric Flow Injection Determination Of Nitrate And Nitrite In Potable Water Using 8-hydroxyquinoline"
J. Chem. Soc. Pak. 1991 Volume 13, Issue 4 Pages 248-252
Yaqoob, M.;Siddiqui, M.A.;Masoom, M.

Abstract: A method based on flow injection analysis is described for the determination of NO3- and NO2-. A mini-column of copperized Ca was used to reduce NO3- to NO2- which was in turn diazotized with 4-aminobenzoic acid and 8-hydroxyquinoline before determination at 485 nm. Sample throughput was 60 h-1. The coefficient of variation was 0.8% for NO3- and 1.0% for NO2-. Sample (25 µL) was injected into a stream of 10 mM Tris buffer of pH 7 (0.5 mL min-1). For NO2- only, the stream was mixed with 25 mM 4-aminobenzoic acid of pH 2, then with 3 mM quinolin-8-ol of pH 12, both pumped at 0.5 mL min-1. After passage through a 60-cm coil the absorbance was measured at 485 nm. For NO2- plus NO3-, the buffer stream was passed through a reduction column (4 cm x 2 mm) packed with copperized cadmium (prep. described) before mixing with the reagents. Calibration graphs were rectilinear for 1 to 9 ppm of NO3- and 0.5 to 4.5 ppm of NO2-, with detection limits of 0.3 and 0.1 ppm, respectively. The sampling rate was 60 h-1. In the above ranges, the mean coefficient of variation were 0.8% for NO3- and 1% for NO2-. The results from a sample of city water agreed with those obtained by the 4-hydroxybenzene-1,3-disulfonic acid method for NO3- and the 4-aminosalicylic acid method for NO2-.
Water Spectrophotometry Buffer Column pH 8-Hydroxyquinoline Reduction column

"UV-spectrophotometric Flow Injection Determination Of Nitrate Using Online Charcoal Column"
J. Chem. Soc. Pak. 1992 Volume 14, Issue 4 Pages 241-243
Yaqoob, M.;Masoom, M.

Abstract: A method is proposed for the determination of nitrate using UV spectrophotometry. The use of oxidized activated charcoal minicolumn online at an elevated pH eliminates organic and inorganic interferences. The absorbance is measured at 225 nm. The procedure has a limit of detection down to 1 mg/L with a relative standard deviation less than 1.0%.
Spectrophotometry Interferences Charcoal Column

"Determination Of Nitrite And Nitrate By Flow Injection Analysis"
J. Flow Injection Anal. 1989 Volume 6, Issue 2 Pages 137-144
K.Aikawa and R.Motohashi

Abstract: For the determination of NO2- in river water, sample (100 µL) was injected into a carrier stream (1 mL min-1) of water and reacted with 4-aminobenzenesulfonamide in dilute HCl (I) and aqueous N-(1-naphthyl)ethylendiamine dihydrochloride (II); both at 1 mL min-1, and after 2 min, absorbance was measured at 540 nm. For the determination of NO3-, the same system was used (diagram given) but the sample was passed through a Cd - Cu reductant column in a carrier stream of 0.1 M NH4Cl before mixing with I and II and detection at 540 nm. Beer's law was obeyed from 0.01 (detection limit) to 2 and 0.05 (detection limit) to 5 mg L-1 of NO2- and NO3-, respectively. Coefficients of variation (n = 10) were 1%. Results obtained correlated well with those of the Japanese Industrial Standards methods.
River Spectrophotometry Injection technique Method comparison Standard method Reduction column

"Reverse FI Method For Successive Determination Of Nitrite And Nitrate In Water With Glass Tube Separator And Gas Phase Chemiluminescence Detection"
J. Flow Injection Anal. 1997 Volume 14, Issue 1 Pages 47-56
Aoki, T.;Kado, N.;Nakaoka, Y.;Mukai, H.

Abstract: NA
Water Chemiluminescence Phase separator Volatile generation Gas phase detection

"Analysis Of Nitrate-nitrogen And Total Nitrogen. Improvement Of Copper-cadmium Method"
Kumamotoken Eisei Kogai Kenkyujoho 1987 Volume 1987, Issue 16 Pages 53-54
Kitaoka, H.;Sugimura, T.;Oda, T.;Nakamura, T.

Abstract: Exptimental results of the determination of NO3- and total N in river and seawater by Cu-Cd reduction method are reported. The method was adopted to flow injection system. (SFS)
River Sea Spectrophotometry Sensitivity

"Instrumentation Based On Microcomputers. 5. A Computer-operated Flow Injection Analyser"
Lab. Microcomput. 1989 Volume 8, Issue 2 Pages 44-52
Malcolme Lawes, D.J.;Pasquini, C.;Wong, K.H.

Abstract: Improvements in the instrument described previously (Anal. Abstr., 1988, 50, 9J17) and its control system are described. The apparatus was applied in the determination of NO2-, NO3-, NH4+ and PO43- in drinking water by conventional colorimetric reactions. Respective calibration graphs were rectilinear up to 0.1, 50, 0.12 and 20 ppm with limits of detection of 4, 30, 5 and 21 ppb. The coefficient of variation (n = 10) were generally 3%.
Water Spectrophotometry Instrumentation Computer Apparatus Calibration Detection limit PPB

"Flow Injection Analysis - New Techniques And Applications"
LaborPraxis 1983 Volume 7, Issue 3 Pages 182-189
Moller, J.

Abstract: A review with 5 references. (SFS)
Gradient technique Hydrodynamic injection

"Continuous-flow. Continuous Determination Of Ammonium In Water And Waste Water"
LaborPraxis 1988 Volume 12, Issue 5 Pages 542-547
Braumann, T.

Abstract: The method is based on the diffusion of NH3 through a selective gas-permeable membrane and collection for differential conductometric detection of NH4+ in H3BO3 solution Use of the GAT N-360 continuous-flow apparatus (illustrated diagrammatically) permits determination of NH3 over a range of 20 to 1000 ppb and analysis of 60 samples h-1 with no significant interference. The method is easily automated. Introduction of a reduction cartridge permits determination of NO3- and NO2- as well as NH3.
Environmental Waste Electrode Automation Gas diffusion Interferences Reduction column

"Enzymic Determination Of Nitrate By Flow Injection Analysis"
LaborPraxis 1991 Volume 15, Issue 6 Pages 479-481
Kuecke, M.

Abstract: The procedure described is based on the reduction of NO3- to NO2- by E. coli cells, chromogenic reaction with sulfanilamide and N-(1-naphthyl)ethylendiamine dihydrochloride, and spectrophotometric detection. Details are given of the preparation of the cell suspension. For analysis of water, the suspension (20 ml) was diluted with 0.1 M phosphate buffer (pH 7.2) (400 ml), whereas for Ca-containing extracts the cell suspension (15 to 25 ml) was centrifuged and the cells were suspended in 0.2 M borate buffer (pH 7.2) (400 ml). Continuous-flow injection analysis was performed by mixing the cell suspension with the sample in phosphate buffer solution (pH 7.2) in a coil (6 m x 0.7 mm) at 37°C, followed by mixing with the color reagent in another coil (30 cm x 0.7 mm) and detection at 540 nm. The procedure is suitable for the analysis of waters, wines, nutrient solution and similar samples.
Environmental Wine Commercial product Spectrophotometry Buffer Heated reaction Enzyme

"Automated Nitrate Assay In Plant Material Following The Flow Injection Analysis Principle"
Landwirtsch. Forsch. 1985 Volume 38, Issue 1 Pages 99-104
Schwerdtfeger, E.

Abstract: Nitrate was determined in plant material by flow injection analysis with Cd reduction to nitrite and absorbance measurement at 540 nm. The relative standard deviation in the range 0.5-5.0 ppm was 1.6%, and the assay obeyed Beer's Law in the range 0.05-10 ppm. Matrix effects were minimized by the standard addition method. (SFS)
Plant Vegetable Spectrophotometry Interferences Standard additions calibration

"Determination Of Nitrites And Nitrates In Milk And Its Products Using Flow Injection Analysis"
Latte 1988 Volume 13, Issue 5 Pages 410-411
Munksgaard, L.L.;Thymark, L.

Abstract: International Dairy Federation methods for the determination of nitrites and nitrates in dairy products were adapted to flow injection analysis (FIA). Samples were defatted and deproteinized, nitrates were reduced to nitrites, and the nitrites were reacted with sulfanilamide and N-naphthylethylenediamine to form a colored product absorbing at 538 nm. The limit of detection for both nitrites and nitrates was <1 mg/kg. At 10 mg/kg the recovery of nitrates was 90-102% and the relative standard deviation was 2-11%. FIA permitted anal. of ~80 samples per day. FIA was superior to manual anal. in terms of all measures of performance. (SFS)
Milk Dairy Products Spectrophotometry Method comparison

"Determination Of Nitrate And Nitrite In Seawater By Flow Injection Analysis"
Limnol. Oceanogr. 1983 Volume 28, Issue 6 Pages 1260-1266
Kenneth S. Johnson, Robert L. Petty

Abstract: The conventional procedure, in which NO3- are reduced to NO2- for determination as an azo-dye, has been automated by means of a flow injection technique. More than 75 determinations can be made in 1 h, or duplicate determinations on discrete samples can be effected at 30 samples h-1. The detection limit is 0.1 µM, and precision is better than 1% at concentration. >10 µM
Sea Spectrophotometry Reverse

"Automated Determination Of Nitrate And Nitrite In Milk And Dairy Products By Continuous-flow Analysis"
Milchwissenschaft 1979 Volume 34, Issue 7 Pages 414-416
Nijhuis, H.;Heeschen, W.;Bluethgen, A.

Abstract: Nitrate is reduced to nitrite by means of an organic hydrazine sulfate solution Nitrite reacts with sulfanilamide and N-(-1-naphthyl)ethylendiamine-2HCl in an azo reaction. The resulting color is measured at 520 nm. For the determination of nitrate and nitrite contents in 1 sample the anal. must be carried out twice: first without hydrazine solution for the determination of the total amt. of nitrate and nitrite. The nitrate content is calculated from the difference of both measurements. The relative standard deviation is 0.66%. The recovery is 100% for nitrite and 99.7% for nitrate. Preservation of milk samples is possible by cooling (up to 3 days at 5°C) or freezing (up to 14 days at -20°C. (SFS)
Milk Dairy Products Spectrophotometry Speciation

"Application Of Automated Flow Injection Analysis To Determine Nitrite And Nitrate In Mouse Brain"
Neuroreport 1994 Volume 5, Issue 13 Pages 1571-1573
Habu H, Yokoi I, Kabuto H, Mori A.

Abstract: Nitric oxide level in the mouse brain was estimated by determination of nitrite and nitrate using an automated flow injection analyzer. for NOx. Different experimental conditions were examined to determine which produced reproducible results. After pretreatment of tissue specimens by the ZnSO4-NaOH method for deproteinization, reproducible and constant values were obtained. The values were more accurate immediately after sectioning without freezing than after 24 h with freezing. Two sacrifice methods, decapitation and microwave irradiation of the head, were investigated, but there was no significant difference between the two. No substances in the mouse brain exerted a positive or negative influence on the results. These results show that our method is indeed applicable to the brain tissue.
Brain

"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.
Environmental Commercial product Spectrophotometry Spectrophotometry Spectrophotometry Electrochemical analysis Review

"Development Of Flow Injection Amperometric Monitors For The Determination Of Nitrate And Other Species"
Port. Electrochim. Acta 1989 Volume 7, Issue 1 Pages 77-83
Fogg, A.G.;Scullion, S.P.;Edmonds, T.E.

Abstract: A review with 14 refs.
Amperometry Review

"Increased Cerebrospinal Fluid Nitrite And Nitrate Levels In Patients With Lumbar Spondylosis"
Res. Commun. Mol. Pathol. Pharmacol. 1996 Volume 91, Issue 1 Pages 77-83
Asahara H, Yokoi I, Tamada T, Kabuto H, Ogawab N, Mori A, Inoue H.

Abstract: Nitric oxide is thought to mediate the cytotoxic effects of certain neurologic diseases. To investigate whether overproduction of nitric oxide may play a role in lumber spondylosis, we compared the levels of nitrite and nitrate in the cerebrospinal fluid (CSF) from patients with lumbar spondylosis with those from a control group by automated flow injection analysis. CSF levels of nitric oxide metabolites were significantly higher in patients with lumbar spondylosis compared with the control (p < 0.01). Nitric oxide may play a role in lumbar pain or nerve damage in sciatic and the CSF nitrite/nitrate may be used as a diagnostic parameter of spinal diseases.
Cerebrospinal Fluid

"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.
Environmental Conductometry Method comparison Interferences Gas diffusion

"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.
Environmental Environmental Electrode Electrode Sample preparation Method comparison

"Successive Determination Of Nitrate And Nitrite By Flow Injection Analysis"
J. Jpn. Water Works Assoc. 1987 Volume 56, Issue 3 Pages 52-56
Tomoda, M.;Maho, A.;Uchida, H.;Satake, H.;Ishikawa, H.;Saito, S.

Abstract: NA

"Simultaneous Determination Of Nitrite And Nitrate By Flow Injection Analysis"
Tec. Lab. 1989 Volume 12, Issue 147 Pages 32-37
Cosano, J.S.;Calle, J.L.;Pinillos, J.L.;Linares, P.;Luque De Castro, M.D.

Abstract: A review is presented, with 30 references, on methods for speciation of nitrogen including one based on an inner-coupling valve system.
Speciation Review Valve

"Waste Water Quality Monitoring"
Trends Anal. Chem. 1997 Volume 16, Issue 7 Pages 419-424
Olivier Thomas*, Frederic Th&eacute;raulaz, Victor Cerd&agrave;, Daniel Constant, Philippe Quevauviller

Abstract: A sequential-injected analysis (SIA) system equipped with two spectrophotometric detectors is described for waste water quality monitoring. The system is portable and gives rapid results for global pollution parameters such as COD, dissolved organic C and total suspended solids and the determination of specific compounds such as nitrate and anionic surfactants using a direct UV method, SIA methods were devised for non-absorbent species such as NH3, organic nitrogen, orthophosphates and organic P.
Waste Spectrophotometry Portable Sequential injection

"Automated Determination Of Nitrate And Nitrite By Flow Injection Analysis"
Voeding. Tech. 1995 Volume 28, Issue 4 Pages 11-14
Klomp, H.;Ellen, G.;De Jong, E.A.M.

Abstract: Application of a Tecator FIA (flow injection analysis) method to determine nitrate and nitrate in milk products is discussed. Trials showed that this method permits easy, rapid and accurate analysis of nitrate and nitrite. Determination of low nitrite concentrations in cheese and baby foods requires some method modifications to achieve sufficient sensitivity. Using the modified method, the detection limit for nitrite in cheese is 0.1 mg/kg. In dried products with a high content of lactose or other compounds which pass through the dialysis membrane, a systematic positive error may occur of the order of 0.05-0.1 mg/kg product; the detection limit is therefore matrix-dependent. Recoveries of nitrate and nitrite (determined by the method of standard additions) are 95-100% for most products. For nitrate concentrations of 10 mg/kg DM and nitrite concentrations of 0.5 mg/kg DM, relative s.d. are approximately 5%.
Milk Product Food Baby Dialysis Standard additions calibration Tecator

"Automated Analyzer ADM300 With Microcomputer-controlled Evaluator AE2-2"
Wasserwirtsch. Wassertech. 1985 Volume 35, Issue 5 Pages 98-99
Mueller, Albrecht; Eulenberg, Horst; Kopprasch, Wolfgang

Abstract: The ADM 300 analyzer for flow-injection anal. of water has a AE2-2 microcomputer-controlled evaluator and can process ~160 samples/day. The flow injection analysis app. can be used for determination of Fe, Mn, NH4+, NO2-, and NO3- in drinking water; P and N determinations in water monitoring; and Fe and P determination in optimization of the use of pptg. agents in wastewater treatment. (SFS)
Waste Water Computer Precipitation

"Evaluation And Comparison Of Ion Chromatography, Segmented-flow Analysis And Flow Injection Analysis For The Determination Of Nitrate In Natural Surface Waters"
Water Res. 1989 Volume 23, Issue 4 Pages 519-521
Eileen M. Burke, F. Xavier Suarez, Daniel C. Hillman,* and Edward M. Heithmar

Abstract: The cited techniques were used in the determination of nitrate (0.04 to 1.5 mg l-1) in water. Suppressed ion chromatography (IC) was performed on an AS4A column, with an AG4 pre-column and an anion micro-membrane suppressor, with a mobile phase (2 mL min-1) of 0.75 mM NaHCO3 - 2.2 mM Na2CO3. For segmented-flow analysis (SFA), a Technicon GTpc AutoAnalyzer II system was used with an ASTM Type II water carrier, sulfanilamide - N-(1-naphthyl)ethylendediamine dihydrochloride color reagent and NH4Cl - EDTA buffer system with a copperized-Cd reduction column. Flow injection analysis (FIA) was performed colorimetrically as in SFA with use of a dual-channel Lachat QuikChem system. The coefficient of variation, accuracy (% recovery) and detection limits were 3%, 103% and 7 µg L-1 for IC, 1%, 101% and 6 µg L-1 for SFA and 1%, 100% and 30 µg L-1 for FIA, respectively. Analysis times were 10 h-1 for IC (including simultaneous Cl- and SO42- determination), and 30 to 60 h-1 for SFA and FIA.
Surface HPLC Buffer EDTA Automation Detection limit Redox Injection technique Column Reduction column Segmented flow Lachat

"The Measurement Of Nitrite, Nitrate And Phosphate With Test Kits And Standard Procedures: A Comparison"
Water Res. 1994 Volume 28, Issue 10 Pages 2223-2228
Franklin I. Ormaza-Gonz&aacute;lez and A. Patricia Villalba-Flor

Abstract: Test kit methods applied with measurement by a Hach DR/2000 spectrophotometer were compared in performance with standard methods of segmented-flow or FIA with measurement by a Shimadzu UV-2100 instrument. Relative detection limits for Hach and Shimadzu instruments, respectively, were 0.3 and 0.048 µM for nitrite, 0.66 and 0.049 µM for nitrate and 0.16 and 0.05 µM for phosphate. Measured mean molecular absorption coefficients in water for Hach and Shimadzu instruments, respectively, were 29,900 and 47,900 for nitrite, 12,000 and 44,500 for nitrate and 21,600 and 22,700 for phosphate. The test kits showed higher reagent blanks and attained stable maximum absorbance readings after 40 min. The kits were evaluated as suitable for determination of nitrite and phosphate in natural waters, but salt interference needed to be taken into account when nitrate was determined.
Environmental Spectrophotometry Interferences Standard method Method comparison

"Flow Injection Analysis Of Substances In Water. 1. Anions. A Critical Review"
Water SA 1987 Volume 13, Issue 4 Pages 197-208
van Staden JF

Abstract: A review is presented, with many references. Possibilities for the determination of SO42-, S2-, Cl-, residual Cl, NO2-, NO3-, silicates, CN- and alkalinity are highlighted.
Environmental Review

"Batch Test Procedures As Tools For Calibration Of Activated Sludge Model - A Pilot Scale Demonstration"
Water Sci. Technol. 1998 Volume 37, Issue 4-5 Pages 235-242
Gert Holm Kristensen, Jes la Cour Jansen and Per Elberg J&oslash;rgensen

Abstract: Various mathematical models have been developed to facilitate the design and operation of biological nutrient removal plants. Proper calibration of such models can be a difficult task due to the large number of variable process coefficients. The paper describes a strategy for model calibration based on batch characterizations of wastewater and activated sludge biomass and demonstrates its applicability through modeling of the process dynamics in a highly dynamic activated sludge pilot plant. A comprehensive experimental program was undertaken comprising batch characterizations of readily degradable and easily hydrolyzable COD in influent wastewater, maximum and endogenous process rates for functional microorganism groups in the activated sludge, and half-satuaration process constants to describe the impact of oxygen on nitrification and denitrification. An online measurement of ammonia and nitrate and nitrite using a flow injection analysis system was conducted for two consecutive days to study the process dynamics in a BioDenitro pilot plant for two parallel activated sludge process tanks. It was possible to closely mimic the dynamics of the nitrogen removal processes in the two tanks based on the model calibration strategy using wastewater and biomass characteristics determined in batch experiments.
Treated Process monitoring

"Use Of Film Flow-through Nitrate-selective Microelectrode For Flow Injection And Ion-chromatographic Determination Of Nitrate"
J. Anal. Chem. 1991 Volume 46, Issue 11 Pages 2193-2196
Kutas, I.M.;Rakhmanko, E.M.;Gonsales, I.;Tarasevich, V.N.;Vinarskii, V.A.

Abstract: A system comprising ion-exchange chromatography with potentiometric detection was developed for the cited determination. Samples were passed through a column (10 cm x 6 mm) of anion-exchange resin (26 to 28 µm), with 2.3 mM to 10 mM KAl(SO4)2 as mobile phase and potentiometric detection vs. Ag - AgCl with a flow-through ion-selective electrode consisting of tetradecylammonium nitrate as electrode-active compound, dibutyl phthalate as plasticizer and PVC. The electode gave a nernstian response from 10 µM to 0.08 M NO3- and the limit of detection was 7.5 µM-NO3-. The method was applied in the determination of NO3- in natural waters with a coefficient of variation (n = 5) of 10%.
Environmental HPIC Electrode Potentiometry Column Resin

"Use Of Ion-selective Electrodes As Anion Detectors In Flow Injection Analysis And Ion Chromatography"
J. Anal. Chem. 1991 Volume 46, Issue 11 Pages 2241-2250
Kolycheva, N.;Muller, H.

Abstract: The NO3-- and anion-selective electrode membranes were prepared from PVC (30%), 2-nitrophenyl octyl ether (66%) as plasticizer and either tributyl octadecylphosphonium nitrate or tetradecylphosphonium sulfate (I), respectively; THF was used as solvent. After formation, the membrane (0.4 mm thick, 5 mm diameter) was attached to solid AgCl - Ag2S membrane; As-prepared NO3- and anion-selective electrodes were conditioned for 24 h in 1 mM NaNO3 and -Na2SO4, respectively. The NO3- selective electrode response was rectilinear for 0.1 mM to 0.1 M NO3-. Selectivity of the I-containing anion-selective electrode decreased in the order SCN-, NO3-, Br-, NO2-, Cl-, HCO3-, H2PO4-, HPO42- and SO42-. Electrodes were used as potentiometric detectors in flow injection analysis and ion chromatography.
HPIC Electrode Electrode Potentiometry Apparatus Selectivity

"Effect Of Nitrogen Fertilization On Growth, Canopy Density, And Yield Of Vitis Vinifera L. Cv. Cabernet Sauvignon"
Am. J. Enol. Vitic. 1999 Volume 50, Issue 3 Pages 351-358
Sally-Jean Bell and Alan Robson

Abstract: The effect of nitrogen supply on the vegetative and reproductive capacity of vines of low nitrogen status was investigated in a field trial conducted in Western Australia. Five rates of nitrogen fertilizer (0, 50, 100, 200, and 400 g N/vine) were applied to irrigated, 12-year-old Cabernet Sauvignon vines over three seasons. Two-thirds of the nitrogen was applied late budbreak and the rest at two weeks after flowering. Moderate rates of nitrogen fertilization stimulated vine growth and vigor (shoot extension rate) resulting in an increase in canopy density. Prior to flowering, maximum vine vigor was observed upon addition of 100 g N/vine. This effect was no longer evident after flowering. Those vines supplemented with 100 g of nitrogen also achieved maximum petiole nitrate concentrations at flowering, growth (shoot length, pruning weight, and leaf area), and canopy density (leaf layer number). Vines receiving 400 g N/vine had shorter shoots and less pruning weight than vines receiving 100 g N/vine, as vigor did not respond to nitrogen fertilizer prior to flowering. However, the petiole nitrate concentration, total leaf area, and canopy density of vines supplied with 200 to 400 g N/vine were no different to those vines supplemented with 100 g N/vine. Nitrogen had no effect on the total vine yield in the first and last season. However, the highest yield came from vines receiving 100 g N/vine in the second season. Additional applications of 200 g and 400 g N/vine increased the yield no further. Higher berry numbers per bunch were associated with the increase in total vine yield. It appeared that moderate rates of nitrogen fertilization can have a beneficial effect on vine productivity in situations where vine nitrogen status is low. In contrast, excessive nitrogen fertilization was an unprofitable exercise as it provided no further benefits in terms of vine productivity.
Fruit Plant

"Effect Of Nitrogen Fertilizer Timing And Rate On Inorganic Nitrogen Status, Fruit Composition, And Yield Of Grapevines"
Am. J. Enol. Vitic. 1994 Volume 45, Issue 4 Pages 377-387
L. Peter Christensen, Mary L. Bianchi, William L. Peacock, and Donna J. Hirschfelt

Abstract: A four-year (1987-90) trial was conducted to study the effects of timing and rate of N fertilizer application on furrow-irrigated Barbera, Grenache, French Colombard, and Chenin blanc grapevines. The objectives were to further determine optimum N fertilizer practices for important wine cultivars in the San Joaquin Valley and to compare inorganic N constituents, NO3--N and NH4+-N, for N status determination. The six treatments included four N fertilizer application timings at budbreak (BB), fruit set (FS), veraison (V), and post-harvest (PH) with a 56 kg N/ha rate, as well as BB with a 2X rate of 112 kg N/ha and control (C0). Vine N status was determined by NO3--N and NH4+-N levels and their sum, total inorganic N (TN), in bloom and veraison petioles. Yield and fruit composition parameters were measured for vine response. Cultivar responses varied widely, with Grenache and Barbera being the high and low extreme cultivars, respectively, in petiole TN status and responsiveness to N treatment; French Colombard and Chenin blanc were intermediate. Generally, TN status increased with increasing N rate (C0 bull BB56 bull BB112). Nitrogen fertilizer timing demonstrated that the more recent N applications often resulted in a higher petiole TN status at the next petiole sampling; i.e., PH56 and BB56 treatment petioles had higher TN status at bloom while FS56 was higher at veraison. Post-harvest timing was found to be particularly effective in supplying petiole TN in the spring; i.e., PH56 sometimes resulted in bloom petiole TN levels comparable to BB112 in all four cultivars and higher than BB56 in Grenache, French Colombard, and Chenin blanc. Petiole NO3--N levels were more sensitive than NH4+-N levels to fertilizer treatment. The greater contribution of NO3--N to TN and their high correlation coefficients as compared to NH4+-N and TN would place in question the utilization of NH4+-N as an additional measurement of N status. Grape soluble solids was the most responsive fruit parameter to N treatment. Generally, N fertilizer decreased soluble solids over C0, irrespective of timing, and with the highest rate (112 kg N/ha) resulting in the largest decrease. Grape yields were only affected in Grenache, with all of the N treatments increasing yields over C0 except V56. This result, plus other negative effects of the V56 treatment, suggest that veraison was the least desirable timing of those compared. Otherwise, timing effects on fruit parameters were minor.
Fruit Optimization