University of North Florida
Browse the Citations
-OR-

Contact Info

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

View Stuart Chalk's profile on LinkedIn

Geological

Classification: Geological

Citations 47

"Spectrophotometric Determination Of Uranium(VI) With 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol In A Flow Injection System"
Anal. Chim. Acta 1985 Volume 169, Issue 1 Pages 109-115
Elaine Anne Jones

Abstract: The sample was injected into a stream of 2% of cyclohexane-1,2-diamine-NNN'N'-tetra-acetic acid, 0.5% of NaF and 2% of ethanolamine in aqueous ethanol (pH 8.5 to 9.5) and mixed with 0.01% 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol solution in ethanol in a 4-m reaction coil. The absorbance of the complex formed was measured at 578 nm. The calibration graph was rectilinear for 0.5 to 20 mg L-1 of U(VI); the coefficient of variation (n = 12) was 1.9% for 10 mg L-1 of U(VI) in a synthetic leach liquor.
Uranium(VI) Spectrophotometry

"Spectrophotometric Determination Of Trace Uranium In Geological Samples By Flow Injection Analysis With Online Levextrel Resin Separation And Preconcentration"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 279-288
Xing Wu and Weiyi Qi

Abstract: Geological materials (0.1 to 0.2 g) were dissolved in mixed acids, the acid was evaporated and the moist residue was dissolved in 1 mL of 7 M HNO3. The solution was mixed with 100 mg of masking agents [NaF - H3BO3 - EDTA (2:8:5)] and diluted to 10 mL with water and the supernatant solution was aspirated in the flow injection system (illustrated). The U was selectively adsorbed on a micro-column (4 cm x 4.4 mm) of Levextrel CL-5209 resin (120 to 200 mesh) and subsequently eluted with aqueous 0.5% NaF - 0.4% diethylenetriaminepenta-acetic acid. The eluate was then mixed with aqueous dye solution (arsenazo III - chloroacetic acid - H3BO3) and the absorbance of the solution was measured at 649 nm. The calibration graph was rectilinear for up to 0.3 mg L-1 of U and the detection limit was 3 µg l-1. The coefficient of variation (n = 11) for 0.03 and 0.18 mg L-1 of U were 4.72 and 0.57%, respectively. Results for eight geological standards agreed with certified values.
Uranium Spectrophotometry Calibration Interferences Optimization Preconcentration Reference material Tecator Resin

"Spectrofluorimetric Flow Injection Determination Of Calcium Using Calcein"
Anal. Chim. Acta 1993 Volume 271, Issue 2 Pages 247-251
N. Chimpalee, D. Chimpalee, R. Jarungpattananon and S. Lawratchavee, D. Thorburn Burns*

Abstract: Calcium was determined fluorimetrically with excitation at 365 nm following reaction with calcein in strongly alkaline solution in a flow injection system. The carrier stream was deionized water and the reagent streams were 0.6 M KOH and 60 µg mL-1 of calcein. The injection rate was 50 h-1. The calibration graph was sigmoid but rectilinear between 3.0 and 7.0 µg mL-1 for injection volume of 250 µL. The method was applied to geological samples.
Calcium Fluorescence

"Selective Flow Injection Sorbent-extraction For Determination Of Cadmium, Copper And Lead In Biological And Environmental Samples By Graphite-furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1994 Volume 293, Issue 3 Pages 251-260
Renli Ma, Willy Van Mol and Freddy Adams*

Abstract: Biological material was heated with HNO3 to fuming, cooled, HClO4 was added, heated at 150°C for 8 h in a sealed bomb and the contents diluted for analysis. Geological material was digested with HF and HNO3 to fuming, digested as above, the bomb contents were evaporated to dryness and the residue dissolved in HNO3. Seawater of pH 1.5 and estuarine water of pH 2 were filtered. Samples were transferred to the FIA system, the stream (8.7 ml/min) was merged with an ammonium diethyldithiophosphate/0.1 M citric acid stream (2.2 ml/min; 0.01% for Cu, 0.1% for Pb and 0.2% or 0.5% for Cd in digests and seawater, respectively) and passed through the ODS sorbent extraction column (40-63 µm) for 20-80 s. After rinsing, elution was effected with ethanol at 5.7 ml/min for 2 s. The eluate was analyzed by GFAAS at 228.8, 324.8 and 283.3 nm and charring/atomization temperature of 400/1500, 1100/2500 and 1100/2300°C for Cd, Cu and Pb, respectively. Calibration graphs were linear up to 0.1, 5 and 4 µg/l with detection limits of 0.003, 0.05 and 0.04 µg/l of Cd, Cu and Pb, respectively. The recoveries for 25-50 ng/l of Cd, 0.5-1 µg/l of Cu and 50 ng/l of Pb from sea and estuarine waters were >87.6%.
Cadmium Copper Lead Spectrophotometry Sample preparation Solid phase extraction

"Flame Atomic Absorption-spectrometric Determination Of Silver In Geological Materials Using A Flow Injection System With Online Preconcentration By Coprecipitation With Diethyl Dithiocarbamate"
Anal. Chim. Acta 1994 Volume 294, Issue 2 Pages 185-193
Shiqiao Pei and Zhaolun Fang*

Abstract: Ground geological material (0.5-1 g) was decomposed with 15 mL of HF, 3 mL of HCl and 1 mL of HClO4. After evaporation to dryness, 10 mL of aqua regia was added and the sample was evaporated to dryness. The residue was dissolved in 2.5 mL of 1 M HNO3 and 20 mL of water and insoluble material was removed by filtration. A 100 µL volume of 3% sulfosalicylic acid and 7.5 mL of 10g/l Fe(III) were added followed by addition of 10% ascorbic acid until the red color completely faded. The solution was diluted to 50 mL after the addition of 2 mL of 1% phenanthroline. The FIA manifold allowed the sample solution stream (4.2 ml/min) to be merged with a 1% diethyldithiocarbamate (DDC) stream (pH 9.2, 0.4 ml/min). The precipitate, Ag co-precipitated with Fe-DDC, was collected in a knotted reactor. The precipitate was dissolved in isobutyl methyl ketone (3.2 ml/min) and introduced into the nebulizer-burner system of an AAS. Ag was determined with an air/acetylene flame at the 0.1-0.01 mg/kg level. An enhancement factor of 26 was obtained with a precipitate collection period of 45 s. The detection limit was 0.5 µg/l in the sample solution and the RSD (n = 11) for 30 µg/l was 2.1%. The sampling frequency was 62/h.
Silver Spectrophotometry Preconcentration Coprecipitation Knotted reactor

"Solvent Extraction Of Arsenic From Acid Medium Using Zinc Hexamethylenedithiocarbamate As An Extractant"
Anal. Chim. Acta 1998 Volume 360, Issue 1-3 Pages 43-52
Anthony R. K. Dapaah and Akimi Ayame*

Abstract: Using zinc hexamethylenedithiocarbamate (Zn(HMDC)2) and flame atomic absorption spectrometry (FAAS) and/or flow injection hydride generation atomic absorption spectrometry (FI-HGAAS), solvent extraction of As(III) from HCl and H2SO4 media into 2,6-dimethyl-4-heptanone (diisobutyl ketone, DIBK) was examined. Arsenic(III) was quantitatively extracted with 2.41 X 10^-3 mol L-1 Zn(HMDC)2 from about 0.004 (pH 2.4) to 4 mol L-1 HCl and H2SO4 aqueous solutions. The logarithmic conditional extraction constant of As(HMDC)3 in the HCl-DIBK system was determined to be 8.3 +- 0.7, by the measurement of the distribution ratios of Zn(II) and As(III). The effectiveness of the proposed extraction method was ascertained in the determination of As in geochemical standard reference materials supplied by the Geological Survey of Japan. Furthermore, the analysis of arsenic in procedural blanks was 0.083+-0.003 µg l-1.
Arsenic Spectrophotometry Spectrophotometry Reference material

"Flow Injection Analysis Of Silicate Rocks For Total Iron And Aluminum"
Talanta 1982 Volume 29, Issue 8 Pages 659-662
Tadashi Mochizuki, Yasuhiko Toda and Rokuro Kuroda*

Abstract: A flow-injection method is described for the spectrophotometric determination of total iron and aluminium in silicate rocks. Rock samples are opened up by fusion with a mixture of lithium carbonate and boric acid, the melt is taken up in 1 M hydrochloric acid and the resulting solution is used for the determination of both iron and aluminium. The flow system for the determination of iron needs no particular reagents, involving simply measurement of the absorbance of the chloro-complex of iron(III) at 335 nm. The system for aluminium consists of the reduction of iron(III) to iron(II), color development with Xylenol Orange (XO), destruction of XO-chelates other than that of aluminium by addition of EDTA and subsequent measurement of the absorbance of the aluminium-XO complex at 506 nm. The systems permit semi-automatic, rapid analysis of silicate rocks for iron and aluminium. Results obtained for standard rocks were in good agreement with the recommended values. The precision ranged from 0.1 to 0.9% for iron and from 0.3 to 0.7% for aluminium.
Aluminum Iron Spectrophotometry

"Electrothermal Atomic Absorption Spectrometric Determination Of Ultratrace Amounts Of Tin By In Situ Preconcentration In A Graphite Tube Using Flow Injection Hydride Generation With Online Ion-exchange Separation"
Talanta 1995 Volume 42, Issue 3 Pages 375-383
Guanhong Tao and Zhaolun Fang*

Abstract: Geological samples (0.5 g) were treated with 5 mL HNO3/HF (7:3) at 40°C. After boiling nearly to dryness a further 2 mL acid was added. After cooling, the digests were diluted to 50 mL and 1 mL was diluted further to 100 mL with 2 M HCl. Hair (0.2 g) or 1 mL serum was acid-treated as above and then the digests were diluted to 50 mL with 2 M HCl. Tap water samples were filtered and acidified to 2 M HCl with concentrated HCl. The samples were passed through a microcolumn (3 cm x 3 mm i.d.) packed with anion-exchanger D-201 (Shenyang Organic Chemicals Co.). The Sn was retained as its chlorostannate complex and subsequently eluted with water into the hydride generation system. The hydride and H2 evolved were separated from the liquid phase in a gas-liquid separator and transferred into a Pd-coated graphite tube pre-heated to 300°C to collect the analyte which was later atomized at 2300°C, followed by AAS. Tin was determined at a sampling frequency of 30/hr with a detection limit of 0.01 µg/l. RSD were ~1.5%.
Tin Sample preparation Spectrophotometry Phase separator Preconcentration Reference material Volatile generation Ultratrace Volatile generation

"Speciation Of Metals In Solution By Flow Injection Analysis. 2. Determination Of Iron(III) And Iron(II) In Mineral Process Liquors By Simultaneous Injection Into Parallel Streams"
Analyst 1984 Volume 109, Issue 7 Pages 843-846
Thomas P. Lynch, Nicholas J. Kernoghan and John N. Wilson

Abstract: Two parallel streams, with simultaneous sample introduction by coupled synchronized injection valves, are analyzed colorimetrically. Bivalent Fe is determined as its 1,10-phenanthroline complex at 508 nm and Fe(III) as its complex with SCN- at 475 nm. With 20 µL samples, the working ranges are 0.5 to 180 ppm and 0.5 to 120 ppm for Fe(III) and Fe(II), respectively, although in each instance the calibration graphs are curvilinear. For max. stability, samples and standard solution should be prepared in aqueous 1% (v/v) HCl. Tolerance limits are listed for 19 species. A novel application is described of the simplex optimization procedure in minimizing the interference of Cu(II) in the determination of Fe(III). For 80 ppm each of Fe(II) and Fe(III), the coefficient of variation are 0.56 and 0.81%, respectively (n = 40). Results are presented for Fe(II) and Fe(III) in HCl extracts of three geological samples. The sampling rate is 120 h-1. (For Part I see Anal. Abstr., 1985, 47, 2H51).
Iron(2+) Iron(III) Sample preparation Spectrophotometry Process control Simplex Optimization Interferences Speciation

"Determination Of Iron In Iron Ores Using Enthalpimetric Flow Injection Analysis"
Analyst 1986 Volume 111, Issue 7 Pages 857-858
Celio Pasquini and Walace A. de Oliveira

Abstract: Samples (0.1 g) of iron ore were digested in 10 mL of concentrated HCl at 60°C. After evaporation to dryness, the residue was dissolved in 1 M HCl. A portion (100 µL) was then injected into a flow manifold after passing through a silver reductor column. The sample solution then merged with a stream of Cr2O72- solution and an enthalpimetric signal due to the oxidation of Fe(II) was generated. The precision was ~0.3% and the sampling rate was 85 h-1. Interference from V was negligible and did not occur with Ti. Results for iron ore samples by the proposed method agreed well with those obtained by titrimetry.
Iron(2+) Enthalpimetry Sample preparation Interferences Method comparison Reduction column

"Chemiluminescence Flow System For Vanadium(V) With Immobilized Reagents"
Analyst 1997 Volume 122, Issue 7 Pages 685-688
Wei Qin, Zhujun Zhang and Chengjie Zhang

Abstract: A portion (0.19 mL) of 0.05 M H3PO4 was injected into an aqueous carrier stream (2.5 ml/min) and passed through a column of anion-exchange resin containing immobilized luminol and hexacyanoferrate(II) (preparation described). The eluate from the column was mixed with the sample stream (1 ml/min), which had previously been passed through a cation-exchange column to remove interfering ions. The resulting solution was merged with a stream (2.5 ml/min) of 0.2 M NaOH and the chemiluminescence produced was measured. A diagram of the manifold used is given. The calibration graph was linear for 0.01-10 µg/ml V(V), the detection limit was 5.4 ng/ml and the RSD (n = 7) was The throughput was 60 samples/h. The method was applied to geochemical materials and hair. A chemiluminescence (CL)-based system for vanadium(v) combined with flow injection analysis is described. The analytical regents, luminol and hexacyanoferrate(II), were both immobilized on an anion-exchange resin column. When a volume of phosphoric acid was passed through the column, these two reagents were eluted from the resin and then mixed with a vanadium(v) stream under acidic conditions. By means of the fast oxidation reaction between vanadium(v) and hexacyanoferrate(II), vanadium(IV) and hexacyanoferrate (III) were generated, both of which catalyzed the oxidation of luminol by dissolved oxygen in aqueous alkaline solution to produce CL. The CL emission intensity was correlated with the standard vanadium (v) concentration in the range from 1.0 x 10^-2 to 10 µg mL-1, and the detection limit was 5.4 x 10^-3 µg mL-1 vanadium(V). Interfering metal ions co-existing in sample solutions could be effectively separated on-line by a cation-exchange column placed upstream. A complete analysis, including sampling and washing, could be performed in 1 min with a relative standard deviation of less than 5%. The system was stable for over 100 analyzes and was applied successfully to the determination of vanadium in geochemical and human hair samples.
Vanadium(V) Ion exchange Chemiluminescence Immobilized reagent Resin Interferences Indirect

"Application Of 2-mercaptobenzothiazole-modified Silica Gel To Online Preconcentration And Separation Of Silver For Its Atomic Absorption Spectrometric Determination"
Analyst 1998 Volume 123, Issue 2 Pages 239-243
Qiaosheng Pu, Qiaoyu Sun, Zhide Hu and Zhixing Su

Abstract: 2-Mercaptobenzothiazole-modified silica gel was used for the flow injection online pre-concentration-separation and determination of silver by flame atomic absorption spectrometry. Two types of manifold, with one or two columns, were adopted. Silver ion was selectively adsorbed from 0.05 to 6 M HNO3 solution and was readily desorbed by thiourea solution The ions coexisting with Ag(I) exhibit virtually no interference in the determination with the exception of Cl-. An Ag(I) concentration ≥1 ppb could be determined reliably if a long pre-concentration time was used. The sample throughput was 60 h-1 using the two-column manifold with a pre-concentration time of 60 s. Ag in a geological sample, a copper metal sample and a lead nitrate sample was determined satisfactorily.
Silver Spectrophotometry Preconcentration Silica gel Interferences

"Use Of A Flow Injection Hydride-generation Technique In Non-dispersive Atomic-fluorescence Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 4 Pages 667-674
Tiezheng Guo, Mingzhong Liu and Werner Schrader

Abstract: Parameters were established for the determination of As, Sb, Bi, Hg, Se and Te. The optimum NaBH4 concentration was 0.4% except for As (0.7%), with a flow rate of 400 to 500 mL min-1 of Ar and a furnace temperature of ~750°C. The calibration graphs were rectilinear within ranges up to 300 µg L-1, and the detection limits were between 0.02 and 0.2 µg L-1. The coefficient of variation ranged from 1 to 2%. The feasibility of using a flow injection (FI) hydride generation technique in conjunction with atomic fluorescence spectrometry (AFS) was investigated. Parameters were established for the determination of Sb, As, Bi, Hg, Se, and Te. Among the parameters that were found to have a more pronounced influence on performance were the concentration. of NaBH4, the carrier gas flow, the observation height, and the temperature of the atomizer cell. Compared with the manual sampling system (or batch system), the relative detection limits of the FI combination were better by factors of 2.5-10. By using FI, the sample volume was reduced to 500 µL, hence, the absolute detection limits were even better with improvements of between 10- and 50-fold depending on the element. The absolute detection limit for Se using the FI technique was 0.035 ng, while with the batch system it was 0.8 ng. Similarly, Hg detection limits with the FI technique and the batch system were found to be 0.015 and 0.4 ng, respectively. The best improvement in the abs. detection limits was found for Te, which with the FI technique was 0.02 ng while with the batch system it was 1.0 ng. The linear ranges were typically 2-3 orders of magnitude of analyte concentrations, which is much wider than that of atomic absorption spectrometry. Sampling frequency was typically 120 injections per h, and since a double-channel AFS instrument was used in this work, pairs of elements such as As, Sb and Bi, Hg were measured simultaneously, which equates to 240 measurements per h. The technique was applied to the determination of hydride forming elements in geological reference materials.
Arsenic Antimony Bismuth Mercury Selenium Tellurium Fluorescence Fluorescence Optimization Reference material Simultaneous analysis Linear dynamic range

"Determination Of Trace And Ultratrace Amounts Of Germanium In Environmental Samples By Preconcentration In A Graphite Furnace Using A Flow Injection Hydride-generation Technique"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 4 Pages 577-584
Guanhong Tao and Zhaolun Fang

Abstract: Trace and ultratrace levels of Ge were determined using flow injection (FI) hydride-generation followed by trapping and electrothermal atomization. Samples of garlic, tap water, ginseng and geochemical reference materials were pre-treated (details given) and diluted with 0.15 M or 3 M HCl then propelled into the FI system and merged with a tetrahydroborate reductant. This generated hydrides together with some H, which were separated in a gas - liquid separator, transferred to a Pd-coated graphite furnace pre-heated to 400°C and atomized by heating to 2500°C. Sensitivities and interference effects using different concentration. of HCl were compared. The use of high acidities and FI rather than batch collection led to reduced interference. Interference studies of 13 metals were performed (results given). Calibration graphs were rectilinear up to 0.5 µg L-1 of Ge for use of 0.15 M HCl and up to 2.5 µg L-1 for use of 3 M HCl with detection limits of 0.004 and 0.03 µg l-1, respectively, using 4.5 mL of sample. Coefficients of variation (n = 11) were 2.0% at 0.3 µg L-1 of Ge in 0.15 M HCl and 2.5% at 1.5 µg L-1 in 3 M HCl.
Germanium Spectrophotometry Phase separator Interferences Reference material Preconcentration Ultratrace

"Flow Injection Preconcentration Of Gold(III) On Cellex T For Determination By Flame Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 7 Pages 801-803
Krystyna Pyrzynska

Abstract: The sample or standard reference material (10 g) was digested in a microwave oven with HNO3/HCl and diluted with HCl. The sample solution was merged with a stream of water on to a glass microcolumn containing Cellex T. Elution was effected by injecting 300 µL of 0.1 M thiourea in 0.1 M HCl and the eluate was transported to the nebulizer for measurement by AAS. Calibration plots were linear up to 100 µg/l. The detection limit was 2.2 µg/l. No interferences were observed from common inorganic ions. The RSD (n = 6) at the 20 µg/l level was 2.6 %. Results for geochemical reference materials were in agreement with the certified values.
Gold(3+) Spectrophotometry Interferences Reference material Preconcentration Cellex

"Online Ion Exchange For The Removal Of Sulfur Anion Interference On The Determination Of Manganese In Geothermal Fluids By Flow Injection Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 7 Pages 479-482
J. L. Burguera, M. Burguera, C. Rivas, P. Carrero, M. Gallignani and M. R. Brunetto

Abstract: Geothermal waters (1 l) were collected (details given) and mixed with 20 mL 1 M triethanolamine. The solution was injected into a flow system (schematic shown) with water as carrier (2.5 ml/min) and drawn through an online anion-exchange column packed with Dowex-1 X8 (NO3- form; mesh size 100-200). Manganese was eluted from the column with 2 mM HNO3 and trapped in a coil. The carrier transferred the analyte to the sample arm assembly and 20 µL portions of the analyte were deposited into the graphite tube atomizer under control of the AAS computer (details given). The analyte was atomized (temperature program details given) and the absorbance of Mn in the vapor produced was measured at 279.5 nm. The calibration graph was linear up to 15 µg/l of Mn and the detection limit was 0.2 µg/l. Inter- and intra-day RSD (n = 10 and 6, respectively ) were 2.8 and 3.2%, respectively, at ~ 5 µg/l Mn. Recoveries were 95-104%. Results agreed well with those obtained by an atomic absorption chelation-liquid-liquid extraction method.
Manganese Ion exchange Spectrophotometry Dowex Interferences Method comparison

"Determination Of Selenium In Geochemical Samples By Flow Injection Hydride-generation Inductively Coupled Plasma Atomic-emission Spectrometry Following Online Removal Of Iron Interference By Anion Exchange"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 4 Pages 487-490
L. D. MARTINEZ, E. SAIDMAN, E. MARCHEVSKY and R. OLSINA

Abstract: A 0.5 g sample was acid-digested by the method of Subramanian (Fresenius' Z. Anal. Chem., 1981, 305, 382), the product was heated with HCl at 90°C for 1 h to reduce Se(VI) to Se(IV), and the resulting solution was diluted to 25 mL. This solution was pumped into the manifold illustrated for retention of the Fe on a microcolumn of Dowex 1-X8, and then passed to an injection valve for injection of a 0.7 mL portion into a carrier stream of water that subsequently merged with streams of 6 M HCl and 0.6% NaBH4 solution. The hydride was then generated in a reaction coil and passed via a gas-liquid separator to the plasma in a stream of Ar. The calibration graph was linear up to 30 ng/ml of Se with a detection limit of 0.3 ng/ml. The RSD (n = 10) was 2% at 20 ng/ml of Se. The results for geochemical standard reference materials agreed well with the certified values.
Selenium Ion exchange Sample preparation Spectrophotometry Sample preparation Solid phase extraction Reference material Volatile generation Phase separator Interferences Dowex Volatile generation

"Determination Of Silver And Gold In Geological Samples By Flame Atomic Absorption Spectrometry After Cloud Point Extraction"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 12 Pages 1369-1373
Márcia Andreia Mesquita da Silva, Vera Lúcia Azzolin Frescura, Faruk José Nome Aguilera and Adilson José Curtius

Abstract: A simple and practical pre-concentration method for low concentrations of Ag and Au, using cloud point extraction, is proposed. The analytes in the initial aqueous solution acidified with hydrochloric acid are complexed with ammonium O,O-diethyldithiophosphate and Triton X-114 is added as a surfactant. After phase separation, based on the cloud point of the mixture, and dilution of the surfactant-rich phase with methanol, the enriched analytes are determined by flame atomic absorption spectrometry, using discrete nebulization. After optimization of the complexation and extraction conditions, enrichment factors of 130 for Au and 91 for Ag were obtained. The complexes have a 1:1 composition. The detection limits are 0.53 ng mL-1 for Au and 0.46 ng mL-1 for Ag in the initial solution. The method was applied to the determination of Au and Ag in acidic solutions of certified reference geological materials and good agreement with the certified values was obtained.
Silver Gold Spectrophotometry Solvent extraction Surfactant Micelle Phase separator Preconcentration

"Semiautomated Method For The Determination Of Selenium In Geological Materials Using A Flow Injection Analysis Technique"
Anal. Chem. 1985 Volume 57, Issue 7 Pages 1482-1485
Chris C. Y. Chan

Abstract: A non-segmented stream is used instead of an air-segmented stream in a continuous-flow system in series with hydride generation and AAS A flow injection module is used for insertion of the sample segment into the stream, and, as air bubbles are not required for mixing and segmenting the solution, narrow tubing can be used throughout. This allows more rapid transport of the sample, the sample zone is better defined and not diluted by the carrier solution, the volumes of sample segments are very reproducible and the sample and reagent solution can be well mixed within a narrow stream, so that the signal response is more rapid and precise with improved peak shape and height. Results from the analysis of 40 reference samples gave coefficient of variation of 15% with a mean of 2.85% (n = 3 to 10). The limit of determination was 5 ppm of Se.
Selenium Spectrophotometry Reference material Peak shape

"Computerized Flow Injection Potentiometric Stripping Analysis With Large-volume Wall-jet Cell"
Fresenius J. Anal. Chem. 1988 Volume 332, Issue 2 Pages 148-152
Wojciech Matuszewski, Marek Trojanowicz and Wolfgang Frenzel

Abstract: A flow injection system is described incorporating a large-volume wall-jet cell (diagram given) and a microcomputer for digital signal recording and data processing. The working electrode was a vitreous-carbon rod of 3 mm diameter pressed into PTFE. A SCE was used as reference electrode and platinum foil (1 cm2) was used as auxiliary electrode. The electrodes were immersed in 0.1 M HCl (carrier solution). The system was applied in the simultaneous determination of Cd and Pb in geological materials. Rock or ore (100 mg) was mixed with 5 mL of 40% HF and heated to dryness in a sand bath at 400°C. The residue was dissolved in 5 mL of 4% H3BO3 and the solution was diluted to 10 mL (rocks) or 50 mL (ore) with 0.1 M HCl. A 750 µL portion of solution was injected; the deposition time was 8 min at -1.15 V vs a SCE; the flow rate was 1.5 mL min-1. Potentiometric stripping was carried out under stopped-flow conditions by using 40 ppm of Hg(II) in 0.1 M HCl as oxidizing agent. Results agreed with those by AAS.
Cadmium Lead Potentiometric stripping analysis Electrode Electrode Computer Method comparison Stopped-flow

"Removal Of Iron Interference In The Determination Of Selenium In Geological Samples By Continuous-flow Hydride Generation ICP-AES"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 1 Pages 126-127
L. D. Martinez, M. Baucells, E. Pelfort, M. Roura, R. Olsina

Abstract: Samples (0.5 g) were digested with 6 mL HCl and 2 mL HNO3, the mixture was cooled, 5 mL HClO4 and 10 mL HF were added and the mixture was left overnight. The solution was evaporated until fumes of HClO4 ceased. This step was repeated until complete solution was obtained, the liquid was treated with 4 mL water and 2 mL HNO3 and diluted to 20 mL with water. The pH was adjusted to 0.5-2 with NH3, 10 mL 2% aqueous ammonium pyrrolidine-1-yl-dithioformate was added and the Fe(III) complex formed was extracted into 10 mL CHCl3. This step was repeated until the extracts were colorless. The aqueous phase was heated with 1 mL HNO3, the Se(VI) was reduced to Se(IV) by heating in 6 M HCl at 60°C for 30 min and the solution was diluted to a suitable volume. In the flow system, 0.6% NaBH4 in 0.5% NaOH was pumped at 1 ml/min, 6 M HCl at 1 ml/min and the sample solution at 6 ml/min. After mixing in a reaction coil, the solution was transferred to a gas-liquid separator and the gas phase was transported into the ICP-AES with Ar (90 ml/min) for measurement. The detection limit was 0.15 ng/ml of Se. Recovery of 50 and 300 ng of Se averaged 96 ± 2.8% and 99 ± 1.1% respectively. Satisfactory results were obtained on three certified samples.
Selenium Spectrophotometry Reference material Interferences

"Selenium Determination By Hydride-generation ICP-AES: Elimination Of Iron Interferences By Means Of An Ion-exchange Resin In A Continuous-flow System"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 7 Pages 850-852
L. D. Martinez, M. Baucells, E. Pelfort, M. Roura, R. Olsina

Abstract: Sample solution prepared from geological materials (details given) was subjected to online SPE on a Dowex 50W-X8 cation-exchange column (5-10 cm x 3 mm i.d.) at 2 ml/min to remove Fe. A portion (500 µL) of the extract was injected into a water stream (6 ml/min), which merged with a stream (1 ml/min) of 6N-HCl and a stream (1 ml/min) of 0.6% NaBH4. The flow passed through a reaction coil (dimensions not given) and into a gas-liquid separator. Volatile hydrides were carried in Ar (90 ml/min) into a plasma torch for ICP-AES determination of Se (operating conditions given). The column eliminated interference from 2.5 mg/ml Fe in the determination of 20 ng/ml Se. The detection limit ws 0.4 ng/ml Se, recoveries were 98-99.5% and the RSD (n = 10) was 2%. Calibration details are not given. The method was applied to geological CRM. The results agreed with the certified values.
Selenium Ion exchange Sample preparation Spectrophotometry Sample preparation Solid phase extraction Reference material Volatile generation Phase separator Interferences Dowex Resin Volatile generation

"Indirect Atomic Absorption Determination Of Aluminum By Flow Injection Analysis"
Microchem. J. 1986 Volume 34, Issue 2 Pages 190-195
Martinez Jimenez, P.;Gallego, M.;Valcarcel, M.

Abstract: Solutions of Al(III) in H2SO4 (pH 3 to 3.5) were injected into a carrier solution of Fe(III) and tartrate (pH 3.5 to 6.0) and Al was determined by AAS by measuring the enhancement of the Fe signal in a fuel-rich air - acetylene flame. The effect depends on the ratio of air to acetylene, and on the geometries of the burner and the optical system. The coefficient of variation (n = 11) for 0.2 to 4 µg mL-1 of Al was 1.2% and the sampling frequency was 150 h-1 for an injected volume of 54 µL. The limits of detection were 6 and 10 ng of Al for 10 and 25 µg mL-1 of Fe, respectively. There was no interference from Br-, I-, F-, Pb(II) and Mg(II). The method was applied to the determination of Al in low-silica magnesite chrome (BCS 396), high-purity magnesite (BCS 389) and feldspar (BAS 29f) to give results in good agreement with the certified values. Interference from foreign ions is discussed.
Aluminum(III) Spectrophotometry Interferences Optimization Reference material Tecator Indirect

"Determination Of Trace Amount Of Silver By Atomic-absorption-spectrometry-coupled Flow Injection Online Coprecipitation Preconcentration Using DDTC-copper As Coprecipitate Carrier"
Microchem. J. 1998 Volume 59, Issue 3 Pages 383-391
Xueqing Mao, Hengwu Chen and Jinsong Liu

Abstract: A flow injection online coprecipitation pre-concentration system with diethyldithiocarbamate (DDTC) chelate of Cu used as the coprecipitate carrier was coupled with flame atomic absorption spectrometry (FAAS) for the determination of trace Ag. Ag was online coprecipitated with DDTC-Cu(II) in 0.5 moL L-1 HCl, and the precipitate was collected in a knotted reactor. The precipitate was then dissolved by iso-Bu Me ketone and transported directly into the nebulizer burner system of a flame atomic absorption spectrometer. A detection limit (3s) of 0.6 µg L-1 was achieved for a loading period of 30 s, a relative standard derivation of 2.0% was obtained for 11 determinations of 20 µg L-1 Ag(I). Interference-free levels were 10 mg L-1 for Cd(II), 50 mg L-1 for Cu(II), 50 mg L-1 for Mn(II), 25 mg L-1 for Ni(II), 100 mg L-1 for Pb(II), 50 mg L-1 for Zn(II), 500 mg L-1 for Fe(III), and 2000 mg L-1 for Fe(II) reduced from Fe3+ by ascorbic acid. The developed method was successfully applied to the determination of trace amount of Ag in geological samples.
Silver Spectrophotometry Coprecipitation Preconcentration Diethyldithiocarbamate Interferences MIBK Knotted reactor

"Determination Of Mercury In Geological Materials By Continuous-flow, Cold Vapor, Atomic Absorption Spectrophotometry"
Anal. Lett. 1987 Volume 20, Issue 6 Pages 899-908
Kennedy, K.R.;Crock, J.G.

Abstract: The sample (0.1 g) is heated at 110°C for 3 h with HNO3 - 25% Na2Cr2O7 and the cooled digest is passed to a continuous-flow manifold for mixing first with air and NaCl - hydroxylammonium chloride - H2SO4 (reducing and complexing agent) and then with 10% SnCl2 solution (to reduce Hg(II) to Hg0). Vapor was released in a phase separator and passed to a Model 457 atomic absorption spectrometer (Thermo Jarrell Ash) equipped with a 6-mA Hg hollow-cathode lamp and operated at 253.7 nm (0.7-nm slit) without background correction. The sample and reagent flow rates and reagent composition were adjusted to obtain max. absorbance for solution containing 10 µg L-1 of Hg. For 10 µg L-1 of Hg, the coefficient of variation was <1.2% (n = 16), and for analysis of SGR-1 standard shale, the mean value was 170 ppb with coefficient of variation of <6%. The detection limit was 20 ppb of Hg, which could be lowered by using a larger sample or smaller dilution volume The only significant interference is from Se.
Mercury Spectrophotometry Interferences Phase separator Reference material

"Determination Of Bismuth In Geological Materials By Flow Injection Hydride Generation Atomic Absorption Spectrometry"
Anal. Lett. 1990 Volume 23, Issue 12 Pages 2259-2272
Chan, C.C.Y.;Baig, M.W.A.;Lichti, P.A.

Abstract: Powdered rock (0.2 g) was digested with HF - HClO4 - HNO3. The evolved hydride was carried through to the heated quartz tube by a stream of Ar and Bi was determined by AAS. Thiosemicarbzide and 1,10-phenanthroline were used as masking agents to control interference from Cu and Ni. Determination levels were 10 ppb and sample throughput was 50 hr-1. Results are compared with the conventional AA method. Results are reported for 13 international geological reference samples.
Bismuth Sample preparation Spectrophotometry Interferences Reference material Method comparison

"Inductively Coupled Plasma - Atomic-emission Spectroscopy With Flow Injection Analysis"
Spectrochim. Acta B 1983 Volume 38, Issue 1-2 Pages 93-105
Stanley Greenfield

Abstract: Flow injection analysis is applied for solution introduction into an inductively coupled plasma discharge. Properties and advantages of transient emission signals, the analysis of Portland cement, and application of signal integration and multielement FIA-ICP are described. The possibilities of FIA-ICP for 'instant' signal-to-background measurement, calibration by standard additions and exponential dilution, and separation methods are evaluated.
Calcium Spectrophotometry Multielement Review

"Determination Of Trace Concentrations Of Bismuth By Inductively Coupled Plasma Atomic-emission Spectrometry With Hydride Generation"
Spectrochim. Acta B 1987 Volume 42, Issue 1-2 Pages 119-128
Taketoshi Nakahara, Kuniyuki Nakanishi and Tamotsu Wasa

Abstract: The continuous-flow hydride-generation apparatus used was as described previously (Anal. Chim. Acta, 1981, 131, 73; Appl. Spectrosc., 1983, 37, 539). The sample solution in 1 M HCl and 1% NaBH4 solution in 1% NaOH were pumped at 16 and 5.5 mL min-1, respectively, and the BiH3 evolved was carried to the ICP in a stream of Ar for the emission intensity at 223.06 nm to be measured. The instrumental coefficient of variation (n = 10) for 0.5, 2, 20 and 200 ng mL-1 of Bi were 3.5, 2.8, 2.2 and 1.3%, respectively, the limit of detection was 0.35 ng mL-1, and a graph of emission intensity vs. log. Bi concentration. was rectilinear for ~1 ng mL-1 to ~10 µg mL-1. The method of standard additions was used for actual determinations, in the presence of 0.1 M thiourea to minimize interference. Results for various geological reference standards, standard copper and standard aluminum alloys (digestion procedures described) agreed well with reported or certified values.
Bismuth Spectrophotometry Sample preparation Interferences Reference material Standard additions calibration Volatile generation Volatile generation

"Analytical Characteristics Of A High Efficiency Ion Transmission Interface (S Mode) Inductively Coupled Plasma Mass Spectrometer For Trace Element Determinations In Geological And Environmental Materials"
Spectrochim. Acta B 1998 Volume 53, Issue 6-8 Pages 1087-1107
I. B. Brenner*, M. Liezers, J. Godfrey, S. Nelms and J. Cantle

Abstract: The analytical performance of a high transmission interface (S mode), inductively coupled plasma-quadrupole mass spectrometer (the VGE Plasma Quad 3) was evaluated for multitrace element analysis of geological and environmental materials. The sensitivity, limits of detection (LODs), effect of Ca and Na and other major elements on mass response, background, percentage 156CeO+/140Ce+, 70Ce++/140Ce+, and long- and short-term variations were compared with those obtained with the conventional mode (normal mode). Normal mode sensitivities varied from 20 MCPS ppm-1 (millions of counts per s per ppm) for 9Be+, 70-80 MCPS ppm-1 for 59Co+, 90 for 115In+ and 40-50 MCPS ppm-1 for the heavy masses. S mode sensitivities were 180 MCPS ppm-1 for 59Co+, 350-380 for 115In+ and 140Ce+, 300 MCPS ppm-1 for 208Pb+, and 150 MCPS ppm-1 for 232Th+ and 238U+, i.e. enhancements amounting to 7. Three s normal and S mode LODs are mainly in the 1-2 and 0.1 ppt range, respectively. S mode LODs are enhanced relative to the normal mode, for masses >80 amu, by factors ranging from ~10 to 50. S mode LODs are depressed relative to normal mode LODs for masses <50 amu by a factor of 10, and the extent of depression is related linearly to mass. In the high- and mid-mass ranges, backgrounds were ~10. They were not affected by sample composition: at 8 amu the S mode background for real samples amounted to ~20, whereas at 220 amu it amounted to four counts. S and normal mode percentage 156CeO+/140Ce++ and percentage Ce++/Ce+ ratios were ~1.5%, and temporal variations were insignificant. The percentage RSDs of normal and S mode Sr+, Ag+ and Pb+ isotope ratios were ~0.1%, with the exception of S mode 208Pb+ and 208Pb+/206Pb+ ratios in the presence of NaCl, which were degraded by a factor of ~2. Normal and S mode long-term variations for continuous aspiration of 0.1% NaCl for periods of up to 13 h were mass dependent, varying from 2.5-4% for 7Li+ and 9Be+ to ~2% for the mid-mass range, increasing slightly to ~3% for high masses. Most of this variation occurred during the 1st 100-150 min of the anal. during cone priming. With compensation, normal and S mode long-term percentage RSDs and drift were reduced to 1-2%. These variations indicate that extended periods of S mode anal. can be conducted without periodic recalibration. A calibration procedure, based on spiked HNO3, was validated by analyzing spiked NaCl solutions, standard water and geological standard reference material (SRM) solutions with internal standardization using conventional solution delivery and flow injection. The agreement of the S mode data and the certified and literature values for ultratrace elements, including ppt levels of rare earth elements in the water standards, was satisfactory. An important conclusion is that ion sampling effects in the S mode are minimal and that the enhanced ion transmission interface is not only beneficial for microanalysis using laser ablation, but for geological and environmental type solutions as well. Sensitivity enhancements were preserved and matrix effects were approximately ±20% for solutions containing 0.1-0.2% total dissolved salt concentration. These variations were reduced to <5% with internal standards matched in mass and ionization potential.
Metals, rare earth Mass spectrometry Interface Reference material Apparatus

"Determination Of Terbium By Flow Injection Analysis And Fluorescence"
Acta Cient. Venez. 1982 Volume 33, Issue 2 Pages 99-102
Burguera, J.L.;Burguera, M.;Gallignani, M.

Abstract: Tb (1 x 10^-2 - 100 mg mL-1) is determined by measuring the fluorescence of the ternary complex Tb(III)-EDTA-sulfosalicylic acid at 545 nm, and an excitation wavelength of ~320 nm. The flow injection analysis technique is used for monitoring the fluorescent reaction. A sample throughout of 90 anal. per h is possible and the relative standard deviation is <4.0% for ~80 pg Tb in 8 uL samples. No interferences was noted from 30-fold excesses of 10 metal ions. (SFS)
Terbium Fluorescence Interferences

"Online Analyzers: Implementation Of Instrument Technology"
Am. Lab. 1992 Volume 24, Issue 18 Pages 20C-20I
Coates, J.;Reber, S.

Abstract: The application of a NIR instrument to on-line analysis in a petroleum refinery operation is described.
Spectrophotometry Process control Automation

"Atomic Absorption Spectrophotometric Determination Of Calcium Silicate Rocks By A Flow Injection Method"
Bunseki Kagaku 1983 Volume 32, Issue 7 Pages T79-T83
Kimura, H.;Oguma, K.;Kuroda, R.

Abstract: Powdered sample (~50 mg) was fused with 150 mg each of Li2CO3 and H3BO3, the fusion cake was dissolved in 1 M HCl to give 100 mL of solution, and a 120 µL portion was injected into a flow system linked to an AAS instrument for determination of Ca at 422.7 nm. To prevent interference from, e.g., Al, phosphate, silicate and SO42-, 130 µL of 2% La solution was mixed with the sample solution by the merging-zone technique. The coefficient of variation (n = 3) for 0.1 to 11% of CaO ranged from 0.3 to 2%, and 180 solution could be analyzed in 1 h. Results for 16 standard rocks agreed well with the certified values.
Calcium Spectrophotometry Sample preparation Interferences Merging zones Reference material

"Continuous Spectrophotometric Determination Of Calcium In Silicates By Flow Injection Analysis"
Bunseki Kagaku 1985 Volume 34, Issue 7 Pages T98-T103
Oguma, K.;Kato, Y.;Kuroda, R.

Abstract: The rock sample (100 mg) was fused with Li2CO3 (300 mg) and H3BO3 (300 mg), the melt was dissolved in 1 M HCl (to 100 ml), and a 1 mL aliquot of the solution was applied to a column of cellulose phosphate (to remove Fe(III) and other polyvalent cations). The Ca-containing fraction of the percolate was diluted to 25 mL and made 0.5 M in HCl, and a 311 µL portion of the solution was injected into the flow system. Calcium was determined, as a complex with o-cresolphthalein complexan, by spectrophotometry, with use of quinolin-8-ol as masking agent for Mg. The results obtained for 14 standard rocks were in good agreement with the reported values; for the determination of 1 to 2.5% and >3% of CaO, the coefficient of variation were 1 to 1.6% and 0.2 to 0.8%, respectively. The flow injection sampling rate was 40 h-1
Calcium Spectrophotometry 8-Hydroxyquinoline Cellulose Column Complexation Interferences Reference material

"Application Of Flow Injection Sample Introduction To Inductively Coupled Plasma - Mass Spectrometry For Geochemical Analysis"
Chem. Geol. 1992 Volume 95, Issue 1-2 Pages 63-71
Andrew N. Eaton, Robert C. Hutton and J. Grenville Holland

Abstract: Geochemical analysis was carried out using ICP-MS with a flow injection sample introduction system. Sample throughput was increased by optimization of the uptake and washout cycles. Small sample volume, such as fluid inclusions extracted by the crush - leach technique, were analyzed using this technique. Flow injection sample introduction improved the matrix tolerance, allowing a dissolved solids content of 5 to 10% whereas conventional sample introduction allows only 0.2 to 2%. Matrix suppression effects produced by solution with high salt content were reduced by changing the dispersion of the flow injection system. Improved detection limits in the sub ng g-1 range are illustrated by the determination of Pt-group metals in a standard reference peridotite. The use of a flow injection (FI) sample introduction system with inductively coupled plasma-mass spectrometry (ICP-MS) is shown to have several advantages. Sample throughput may be increased by optimizing uptake and washout cycles. Small volume samples, such as fluid inclusions extd. by the crush-leach technique, may be analyzed. Dissolved solids contents can be increased from 0.2-2% w/v for conventional sample introduction, to 5-10% w/v for flow injection. Matrix suppression effects, produced by high salt content solutions, such as brines, may be reduced by changing the dispersion of the flow injection system. Finally, improved detection for FI-ICP-MS limits are illustrated by the determination of the platinum-group metals in standar reference peridotite PCC-1, where values in the range 0.03-0.3 mg g-1 were obtained.
Platinum Sample preparation Mass spectrometry Optimization Reference material Interferences

"Determination Of Rare-earth Elements By Ion Pair HPLC With Post-column Derivatization Using Arsenazo III"
Collect. Czech. Chem. Commun. 1988 Volume 53, Issue 8 Pages 1664-1677
Kuban, V.;Gladilovich, D.B.

Abstract: A portion (10 to 25 µL) of sample solution (prep. described) was analyzed on a column (15 cm x 3 mm) of Separon SGX C18 (5 µm) modified with sorbed ammonium dodecyl sulfate, protected by a column (5 cm x 3 mm) of Separon SGX C18 (5 µm) or Silperl silica gel (14 µm) with a mobile phase (1 mL min-1) of 20 to 160 mM ammonium DL-2-hydroxy-2-methylpropionate(I) solution (pH 4.5). Post-column derivatization was achieved with 5 µM-arsenazo III in 0.1 M formate buffer (pH 2.9 to 3.0); detection was at 660 nm. With isocratic elution, calibration graphs (peak height vs. concentration.) were rectilinear from 10 to 150 ng of rare-earth metal in 10 or 25 µL injected. With stepwise gradient elution with 40 mM I for 5 min, 80 mM I for the next 10 min and 160 mM I after 15 min, the calibration graphs were rectilinear from 6 to 155 ng of rare-earth metal in 10 or 25 µL injected. The method was applied in the determination of rare-earth metals in apatite, oxide concentrates, and a phosphor. Results agreed well with those obtained by optical methods.
Metals, rare earth HPLC Spectrophotometry Method comparison Post-column derivatization

"Use Of Sulfhydryl Cotton Fiber For Preconcentration And Determination Of Trace Gold In Geochemical Samples By Flow Injection Chemiluminescence Analysis"
Fenxi Huaxue 1987 Volume 15, Issue 12 Pages 1120-1122
Lu, J.R.;Zhang, X.R.;Zhang, Z.J.

Abstract: The sample was treated with aqua regia and Au was separated and pre-concentrated by adsorption on a column (7 cm x 4 mm) of mercaptoacetoxycellulose fiber. Co-adsorbed elements were eluted with 6 M HCl and then water, and the fiber was burnt in a crucible. The residue was dissolved in aqua regia and the solution was evaporated to dryness. After dissolving the residue in 0.1 M HCl and addition of KIO3 and H2O2 (as stabilizing reagent for Au(III)), the Au(III) was determined by flow injection chemiluminescence analysis with luminol - H2O2 - EDTA. The method was applicable in the range 0.7 ppb to 7 ppm.
Gold Chemiluminescence Sample preparation Membrane Mercaptoacetoxycellulose fiber Preconcentration Sulfhydryl cotton

"Determination Of Trace Arsenic, Selenium, Molybdenum, Sulfur And Chromium With Online Flow Injection Anion-exchange Preconcentration Inductively Coupled Plasma Atomic-emission Spectrometry"
Fenxi Huaxue 1993 Volume 21, Issue 3 Pages 328-330
Liu, E.;Chen, W.J.;Zhao, C.Y.

Abstract: A system for online flow injection anion-exchange pre-concentration. ICP-AES (diagram given) for determination of As, Se, Mo, S and Cr is described. Sample solution was passed through two parallel columns (8 cm x 2 mm) packed with D296 anion-exchange resin (40 mesh) at a flow rate of 1.23 mL min-1 for pre-concentration.; elution was effected with 0.5 M NH4Cl and 3 M NH3 (1.23 mL min-1) and exposure time was 40 s. The detection limits were 13, 25.2, 2.04, 6.19 and 3.64 ng mL-1 for As, Se, Mo, S and Cr, respectively. The method was used for the analysis of geological, hair and bovine liver standards. Results agreed with the certified values.
Arsenic Selenium Molybdenum Sulfur Chromium Spectrophotometry Sample preparation Ion pair extraction Reference material Preconcentration

"Determination Of Germanium In Geological Materials By Spectrophotometry With Flow Injection Crystal Violet-molybdogermanic Acid"
Fenxi Huaxue 1995 Volume 23, Issue 6 Pages 739-739
Pei, S.Q.;Chen, Y.Y.

Abstract: Sample was dissolved with HNO3, HF and H2SO4 and treated with HCl until the HCl concentration was 9M. The acid solution was extracted with 2 x 10 mL benzene and back-extracted into 4 mL water. The aqueous solution was acidified until color of nitrophenol was discharged and diluted to 5 mL. A 200 µL portion of the diluted solution was injected into the carrier stream of 0.2% polyvinyl alcohol (2.1 ml/min) of the flow injection analyzer and mixed with a stream of 0.1 M Na2MoO4 (1.8 ml/min) in a reaction tube (1 m x 0.8 mm i.d.) and with 0.2 mM crystal violet (1.8 ml/min) in another tube (2 m x 0.8 mm i.d.) and finally with 10% HNO3 (1.8 ml/min) in a reactor (4 m x 0.8 mm i.d.). The absorbance of the resultant complex was measured at 595 nm. The calibration graph was linear up to 3 µg/ml of Ge. Recoveries were 99.3-99.8% and the RSD was 1.53%. Large amounts of Si(IV) interfered. Sampling frequency was 80 runs per h.
Germanium Spectrophotometry Interferences

"Flow Injection Catalytic Spectrophotometric Determination Of Trace Amounts Of Vanadium In Geochemical Exploratory Samples"
Fenxi Huaxue 1996 Volume 24, Issue 7 Pages 838-840
Liu, G.J.;Li, J.X.;Zhao, X.M.

Abstract: Sample (2-50 mg) was digested with 2 mL H2SO4 (1:1), 2 mL concentrated HCl and 5 mL HF and the digest was applied to a strongly-basic anion-exchange resin column. Portions (200 µL) of eluate were injected, via a sampling coil, into a carrier stream of 9% ascorbic acid at 0.75 ml/min and mixed with a reagent stream containing 0.005% beryllon III and ammonium acetate/ammonia water buffer of pH 7.5 at 0.75 ml/min in a reaction coil (830 cm x 0.5 mm i.d.) at 90°C. The colored products formed were detected spectrophotometrically at 480 nm. The amount of V was calculated after evaluation of the absorbance difference with that of a reagent blank. The calibration graph was linear up to 80 µg/l of V with detection limit of 7 µg/l. The RSD (n = 30) was 0.6% for 0.4 mg/l of V. Analysis time was reduced from 1 h by the conventional technique to ~e;1 min by this method. Interference from co-existing foreign ions, viz. Cu(II), Fe(III), Mo(V), Ni(II), Ce(IV), As(V) and Pb(II) were removed during the ion-exchange treatment. Sampling frequency was 60 runs per h.
Vanadium Spectrophotometry Interferences

"Flow Injection Online Preconcentration And Simultaneous Spectrophotometric Determination Of Gold, Palladium And Silver"
Fenxi Huaxue 1998 Volume 26, Issue 1 Pages 7-11
Song, H.;Wang, H.;Song, M.;Wang, D.

Abstract: A new system of flow injection online pre-concentration with VS-II anion exchange fiber was established for simultaneous spectrophotometric determination of trace Au, Pd and Ag in geological samples. A FIA simultaneous determination method based on elution curves was established. The ANN calculation was used to deal with the nonlinear data, and the application and influence factors of B-P algorithm were studied. The study on three kinds of multivariate calibration methods showed that the B-P algorithm has a strong correction capability for nonlinear data.
Gold Palladium Silver Ion exchange Spectrophotometry Preconcentration Multivariate calibration Simultaneous analysis Anion exchange fiber

"Determination Of Trace Arsenic In Geological Samples By Flow Injection Hydride Generation-vapor Storage And Pulsed Sampling Atomic Fluorescence Spectrometry"
Guangpu Shiyanshi 1998 Volume 15, Issue 5 Pages 28-31
ZHOU Junming, CHENG Xianghong

Abstract: A method for the determination of trace As in geological samples by flow injection hydride generation-vapor storage and pulsed sampling atomic fluorescence spectrometry was developed. The performances of two kinds of vapor storage system were compared. The analytical sensitivity of As has increased by 1760%. The detection limit is 0.32 ng/mL and relative standard deviation 2.1%. Analytical results of geological standard reference materials are satisfactory.
Arsenic Fluorescence Reference material

"Study On The Determination Of Magnesium By Flow Injection Analysis - Flame AAS Using A Single-standard-solution Continuous-dilution Calibration Technique"
Guangpuxue Yu Guangpu Fenxi 1990 Volume 10, Issue 1 Pages 38-41
Hou, X.;Xu, P.;Sun, Z.

Abstract: The method is based on that described by Tyson et al (cf. Talanta, 1984, 31, 9). A simple flow injection analysis - flame AAS apparatus was designed and applied to determine Mg in water and geological samples. The absorbance was measured at 285.2 nm. The coefficient of variation is 0.41% and recoveries were 99.3 to 101% when determining 50 to 250 µg of Mg.
Magnesium Spectrophotometry

"Extractive Chromatographic Online Preconcentration-flow Injection Flame Atomic Absorption Spectrometric Determination Of Trace Silver In Geological Samples"
Guangpuxue Yu Guangpu Fenxi 1998 Volume 18, Issue 5 Pages 593-596
Yuan, Y.;Guo, X.

Abstract: Extractive choromatography using a TPP column was applied to pre-concentration and matrix separation for trace silver in geological samples. A flow injection online method for the determination of silver by flame AAS is described. An enrichment factor of 20 was achieved at a sampling frequency of 30 times/h. The precision RSD is 2.0% for the analysis of a geochemical standard reference material (GSD-12, n = 11) and the detection limited obtained (3s) is 0.02 µg/g.
Silver Spectrophotometry Preconcentration

"Flow Injection Analysis Of Silicate Rocks. 1. Flow Injection Analysis-AAS Determination Of Calcium In Diatomite"
Jilin Daxue Ziran Kexue Xuebao 1986 Volume 24, Issue 4 Pages 93-97
Wei Qingxun, Guo Yaxian, Liu Miao and Ben Yuezhi

Abstract: A pulse-free carrier stream was obtained for flow injection analysis (FIA) - atomic absorption spectrometry (AAS) by omitting the peristaltic pump and buffer applied. The pressure difference in the atomizer served as the driving force. Calcium was determined in diatomite by dissolving the sample with a HF-HNO3 mixture, using a lanthanum solution for eliminating the interferences, and AAS. The relative standard deviation is ≤2%.
Calcium Spectrophotometry Sample preparation Extraction

"Determination Of Trace Gold In Geological Samples With Flow Injection-diphenylthiourea Cellulose Online Preconcentration-FAAS"
Kuangwu Yanshi 1998 Volume 1998, Issue 3 Pages 107-112
Li, L.;Su, Q.;Li, L.

Abstract: Trace Au in geological samples was pre-concentrated with diphenylthiourea cellulose prepared in the laboratory, and determined by FI-FAAS. The method had a determination speed of 30 samples/h, a sensitivity 0.31 µg/mL (1 absorption), and relative standard deviation ±2.59.
Gold Spectrophotometry Preconcentration Cellulose

"Performance Of An FIA - Flame AAS System Using An Electromagnetic Valve As Sampler"
Yankuang Ceshi 1989 Volume 8, Issue 4 Pages 300-303
Xu, P.;Hou, X.;Zhou, X.;Yan, D.

Abstract: A FIA - flame AAS apparatus with an electromagnetic valve as sampler is described. Factors influencing the dispersion and sampling frequency of the FIA as well as the precision of the whole system were investigated, e.g., the sampling volume, velocity of carrier flow and length of reaction circle. The system has been used in the determination of Li in brine by the standard-addition method and in the determination of Pd in geological samples after mercaptobenzothiazole - methylisobutyl ketone extraction.
Lithium Palladium Spectrophotometry Apparatus MIBK Precision Valve Standard additions calibration

"Determination Of Arsenic, Antimony And Bismuth In Geological Samples By Atomic Absorption Spectrometry With Continuous-flow Hydride Generator"
Yejin Fenxi 1993 Volume 13, Issue 2 Pages 11-14
Guo Xiaowei, Tong Kaiyuan

Abstract: A simple continuous-flow hydride generator is designed and its construction is described. By using the device, the precisions and detection limits of As, Sb, Bi, Se, Te and Hg are tested, and the results obtained agreed with the literature values. An analytical method for determining As, Sb and Bi in geological samples and standard reference samples is reported.
Arsenic Antimony Bismuth Spectrophotometry Volatile generation Reference material Volatile generation