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

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Citations 6

"Determination Of Cadmium In Seawater Using Automated Online Preconcentration And Direct Injection Graphite Furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 255-262
D. Colbert, K. S. Johnson and K. H. Coalea

Abstract: An online pre-concentration method for the determination of cadmium in seawater was developed for graphite furnace atomic absorption spectrometry (GFAAS) using deuterium lamp background correction. The technique was adapted from a previously reported technique and was fully automated. Automated pre-concentration of cadmium reduced the concentrations of matrix elements in samples to levels that did not interfere with the determination of cadmium at ultratrace levels. The soluble ligand, 1-pyrrolidinecarbodithioic acid (APDC), was mixed with the sample in a continuous-flow system to form a nonpolar metal complex which was absorbed onto a C18 column. The metal complex was then eluted from the column directly into the graphite furnace. The addition of an inline nitric acid rinse step between sample load cycles allowed for the determination of cadmium with one elute cycle. Other modifications included lab. purifn. of the ammonium acetate rinse solution, a nonbuffered APDC ligand solution, and a computer-activated load cycle to reduce sample consumption. The average column recovery was 73% with a sample loading flow rate of 2.2 mL/min and 55 s pre-concentration time. Sample throughput was ~15 samples/h with 2 mL of sample pre-concentrated and analyzed every 4 min. The small sample volume required made this method useful where sample volumes are limited. The 3s limit of detection for replicate blanks was 42 pM Cd (n = 5) for a 2 mL sample. The effectiveness of the method was demonstrated for the determination of Cd in certified open ocean reference materials NASS-3 and NASS-4. Analysis of Cd in equatorial Pacific seawater demonstrated that the system produces oceanographically consistent results.
Cadmium Spectrophotometry Preconcentration Reference material C18 APDC

"Immobilization Of 8-hydroxyquinoline Onto Silicone Tubing For The Determination Of Trace Elements In Seawater Using Flow Injection ICP-MS"
Talanta 1998 Volume 47, Issue 2 Pages 439-445
S. N. Willie*, H. Tekgul and R. E. Sturgeon

Abstract: A rapid and simple online method is described for the pre-concentration of Mn, Co, Ni, Cu, Zn, Cd and Pb from seawater using 8-hydroxyquinoline immobilized onto silicone tubing (Sil-8-HQ) via the Mannich reaction. Recoveries 35-95% and limits of detection in the ppt range were obtained using a 2 m long Sil-8-HQ tube with a sample flow rate of 1.0 mL/min. A tube could be subjected to sample loading and elution cycles over 200 times. The capacity was 1.5 and 1.3 µg/cm2 for Cu and Mn, respectively. Cu, Cd, Co, Pb, Mn, Zn and Ni were determined in coastal and open ocean seawater using flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS). Good agreement with certified values for the certified reference materials NASS-4 and CASS-3 was demonstrated when quantitation was undertaken by the method of additions
Manganese Cobalt Nickel Copper Zinc Cadmium Lead Mass spectrometry Tube wall immobilization Silicone tubing 8-Hydroxyquinoline Preconcentration Reference material Standard additions calibration

"Evaluation Of Electrochemical Hydride Generation For The Determination Of Total Antimony In Natural-waters By Electrothermal Atomic Absorption Spectrometry With In-situ Concentration"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 3 Pages 225-230
W.-W. Ding and R. E. Sturgeon

Abstract: A continuous-flow (timed injection) electrochemical hydride generation system was developed for the determination of total Sb in river water and seawater. Lead was used as cathode material for the production of stibine. Both Sb-III and Sb-V were equally converted into their hydrides by electrochemical means with 92±4% efficiency. The hydride was trapped in a Pd-coated graphite furnace prior to atomization. An absolute detection limit of 45 pg (3s(blank)) and a concentration detection limit of 0.02 µg L-1 were obtained using 2 mi sample volumes. The precision of replicate measurements at the 0.2 pg L-1 level (0.5 ng absolute mass level) was better than 6% relative standard deviation. The accuracy of the approach was verified through the analysis of National Research Council of Canada certified reference materials SLRS-2 and SLRS-3 River Water and NASS-4 Open Ocean Seawater.
Antimony, total Spectrophotometry Electrochemical product generation Reference material Interferences Timed injection

"Online Solid-phase Chelation For The Determination Of Eight Metals In Environmental Waters By Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 3 Pages 187-191
Daniel B. Taylor, H. M. Kingston, Donald J. Nogay, Dagmar Koller and Robert Hutton

Abstract: Seawater was mixed with 4 M ammonium acetate buffer, the pH was adjusted to 5.5 and diluted with water. The prepared seawater or natural water was loaded into a flow injection system at 2.4 ml/min and the sample merged with a buffer solution (2 ml/min) of 4 M ammonium acetate of pH 5.8 which had passed through a clean up Al-clad PEEK column (7.5 cm x 4.6 mm i.d.) packed with Muromac A-1 (50-100 mesh). The resulting solution was loaded on to a PEEK column (5 cm x 4 mm i.d.) and the column was washed with water. Weakly retained matrix components were eluted with buffer and the buffer was washed off the column with water. The metal analyzes were eluted with 1 M HNO3 and the eluate passed to the ICP-MS instrument via a V groove nebulizer. Eight metals (14 isotopes) were determined with detection limits of 0.5-60 ng/l for a 10 mL sample to 0.11-12 ng/l for a 50 mL sample (results tabulated). The results for the analysis of water reference materials are tabulated and discussed.
Metals Mass spectrometry Sample preparation Reference material Chelation Solid phase extraction Muromac

"Determination Of Copper, Cadmium, Lead, Bismuth And Selenium(IV) In Sea-water By Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry After Online Separation"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 5 Pages 363-369
Dirce Pozebon, Valderi L. Dressler and Adilson J. Curtius

Abstract: A procedure for the determination of Cu, Cd, Pb, Bi and Se(IV) in seawater by electrothermal vaporization inductively coupled plasma mass spectrometry, after online separation using a flow injection system, is proposed. Matrix separation and analyte pre-concentration. was accomplished by retention of the analytes complexed with the ammonium salt of O,O-diethyldithiophosphoric acid on C18 immobilized on silica in a minicolumn coupled directly to the autosampler arm of the vaporizer. The methanol used as eluent was vaporized after being automatically injected into the graphite tube, prior to the vaporization of the analytes. The conditions for the online complexation and separation as well as the vaporizer temperature program were optimized. The recoveries from seawater were 90-110%. The accuracy of the method was tested by the anal. of 2 certified seawaters, CASS-3 and NASS-4, from the National Research Council of Canada. The concentration. of Bi in these seawaters was below the method detection limit. The relative standard deviation was <10% (n=6). The throughput was 22 samples/h and the volume of sample consumed was only 2.3 mL. Tl and As(III) were also separated but their complexation in seawater was not efficient.
Copper Cadmium Lead Bismuth Selenium(IV) Mass spectrometry Ion pair extraction C18 Silica Preconcentration Reference material

"Direct Determination Of Trace Metals In Sea-water By Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 11 Pages 1239-1244
Eivind Rosland and Walter Lund

Abstract: The direct determination of trace metals in seawater by inductively coupled plasma mass spectrometry (ICP-MS) is described, based on sample introduction by flow injection analysis (FIA) and electrothermal vaporization (ETV). FIA-ICP-MS was used for the determination of Mn, Mo and U; 500 µL of 1+9 diluted seawater were injected in a carrier stream of 0.028 mol/L HNO3. The detection limits were 0.7 µg/L Mn, 1.4 µg/L Mo and 0.10 µg/L U. ETV-ICP-MS was used for the determination of Cd and Pb. The analytes were vaporized as chlorides at 800°C, without interference from the matrix elements. The detection limits were 4.1 ng/L for Cd and 0.8 ng/L for Pb. The FIA-ICP-MS and ETV-ICP-MS results were validated by analyzing a reference seawater sample (NASS4).
Manganese Molybdenum Uranium Mass spectrometry Interferences Reference material Method comparison