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

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Classification: Marine -> shellfish -> mussel

Citations 11

"On-line Preconcentration System For Lead Determination In Seafood Samples By Flame Atomic Absorption Spectrometry Using Polyurethane Foam Loaded With 2-(2-benzothiazolylazo)-2-p-cresol"
Anal. Chim. Acta 2001 Volume 441, Issue 2 Pages 281-289
Valfredo A. Lemos and Sérgio L. C. Ferreira

Abstract: In the present paper, an on-line system for enrichment and determination of lead is proposed. It is based on the chemical sorption of lead(II) ions on a minicolumn packed with polyurethane foam loaded with 2-(2-benzothiazolylazo)-2-p-cresol (BTAC) reagent. After pre-concentration, lead(II) ions are eluted by 0.10 mol L-1 hydrochloric acid solution and determined directly by flame atomic absorption spectrometry (FAAS). Chemical and flow variables as well as effect of other ions were studied. The results demonstrated that lead could be determinate with an enrichment factor of 26 for a sample volume of 7.0 mL and pre-concentration time of 1 min. The detection limit (3 s) was 1.0 µg L-1 and the precision (assessed as the relative standard deviation) reached values of 6.0-0.7% in lead solutions of 10^-500 µg L-1 concentration, respectively. The enrichment factor and the detection limit can be further improved by increasing pre-concentration time without degradation in the efficiency due to the favorable kinetics and low hydrodynamic impedance of the present system. Achieved sampling frequency was 48 samples per hour. The effect of another ions in concentrations agreeing with biological samples was studied. It was found that the proposed procedure has necessary selectivity for lead determination in seafood and other biological samples. The accuracy was confirmed by analysis of the followings certified reference materials: fish tissue IAEA, lobster hepatopancreas NRCC TORT-1 and citrus leaves NIST 1572. Recoveries of spike additions (0.2 or 1.0 µg g-1) to several seafood samples were quantitative (90-107%). These results proved also that the procedure is not affected by matrix interferences and can be applied satisfactorily for lead determination in samples of shrimp, oyster, crab, fish and mussel contaminated by it.
Lead Spectrophotometry Preconcentration Interferences Amberlite Polyurethane foam Solid phase extraction

"Flow Potentiometric Stripping Analysis For Mercury(II) In Urine, Sediment And Acid Digest Of Biological Material"
Anal. Chim. Acta 1982 Volume 141, Issue 1 Pages 157-162
Daniel Jagner and Kerstin Årén

Abstract: In flow potentiometric stripping analysis for mercury in urine, the samples are acidified with concentrated nitric acid and heated to boiling for 10 min. After cooling, the samples are buffered by the addition of concentrated ammonia and then pre-electrolysed at a gold working electrode for 90 s at -0.25 V vs. SCE at a flow rate of 1.75 mL min-1. The stripping solution is 1 M sodium bromide solution acidified with 0.1 M hydrochloric acid and containing chromium(VI). The detection limit at one σ level is 0.05 µM. Orchard leaves, sediment and fish muscles are digested in nitric acid at 140°C for 30 min prior to buffering with ammonia and potentiometric stripping analysis for 200 s at -0.20 V vs. SCE at a flow rate of 1.75 mL min-1.
Mercury(II) Clinical analysis Potentiometric stripping analysis Sample preparation

"Trace Metal Enrichment By Automated Online Column Preconcentration For Flow Injection Atomic Absorption Spectrometry"
Anal. Chim. Acta 1989 Volume 221, Issue 1 Pages 65-76
Shizuko Hirata, Kazuto Honda, Takahiro Kumamaru

Abstract: Trace metals were pre-concentrated on a micro-column (7 mm x 4 mm) of Muromac A-1 (50 to 100 mesh) at a flow rate of 5 mL min-1. Ions were eluted with 2 M HNO3 (4.85 mL min-1), before analysis by flame AAS. Optimum pH was established for metal ion uptake from sample solution The coefficient of variation for 20 mL samples containing 5 to 100 µg L-1 of Cd, Cr, Cu, Fe, Mn, Pb or Zn were 0.7 to 1.7% (n = 3 or 4). Values for Cd and Cr in standard reference materials of plants, mussel tissue and pond sediment were within the specified range.
Cadmium Chromium Copper Iron Manganese Lead Spectrophotometry Column Preconcentration Muromac Reference material Optimization pH

"Determination Of Ninhydrin Positive Substances In Seawater And Hemolymph"
Analyst 1995 Volume 120, Issue 8 Pages 2097-2099
Saloua Sadok, Roger Uglow and Stephen J. Haswell

Abstract: A flow injection spectrophotometric method for determining ninhydrin positive substances (α-amino-acids) in seawater and in hemolymph from mussels (Mytilus edulis) is described. Hemolymph was diluted with saline before analysis; seawater was used directly. The sample (0.5 ml) was mixed with 1 mL 3% ninhydrin and heated in a boiling-water bath for 12 min, 1 mL 0.8 M HCl was added and the mixture was heated for a further 10 min. A portion (0.3 ml) of the solution was injected into an aqueous carrier stream (1 ml/min) and mixed with a stream (1 ml/min) of 1.2 M NaOH in a 15 cm mixing coil to produce NH3. The solution was then passed over a microporous PTFE membrane through which the NH3 diffused into a stream (1 ml/min) of 0.4 g/l Bromothymol Blue. The absorbance of the colored solution was measured at 635 nm. The calibration graph was linear up to 60 µM-alanine and the detection limit was 0.3 µM. The RSD (n = 6) was 2%. Recoveries were quantitative.
Amino acids, α Spectrophotometry Teflon membrane Gas diffusion

"Determination Of Cadmium In Mussels By Flame Atomic Absorption Spectrometry With Preconcentration On A Chelating Resin In A Flow Injection System"
Analyst 1998 Volume 123, Issue 1 Pages 105-108
M. F. Enríquez-Domínguez, M. C. Yebra-Biurrun and M. P. Bermejo-Barrera

Abstract: A flow injection pre-concentration system with a chelating resin was developed to determine trace and ultratrace amounts of cadmium in mussels by flame atomic absorption spectrometry. The metal was pre-concentrated on a microcolumn packed with poly(aminophosphonic acid) resin and eluted with dilute hydrochloric acid into the nebulizer-burner system of an atomic absorption spectrometer. A pre-concentration factor of 16-47, equivalent to 3.4-10 mL of sample, was achieved by using a time-based technique. The detection limit (3s) in the sample digest was 0.56 µg/L-1 for a sample volume of 3.4 mL. The precision (relative standard deviation) obtained for different amounts of cadmium was in the range 1.4-6.6% at the 1-20 µg/L-1 level. Chem. and flow variables, and other figures of merit of the proposed methodology, were studied. The method demonstrates high tolerance to interferences, and the anal. results obtained for a certified reference material were in good agreement with the certified value. The method was successfully applied to the determination of trace amounts of cadmium in mussel samples from estuaries in Galicia (Spain).
Cadmium Spectrophotometry Chelation Preconcentration Resin Polyaminophosphonic acid Reference material Optimization Interferences

"Thermospray - Micro-atomizer Interface For The Determination Of Trace Cadmium And Cadmium Metallothioneins In Biological Samples With Flow Injection - And High Performance Liquid Chromatography - Atomic Absorption Spectrometry"
Anal. Chem. 1992 Volume 64, Issue 24 Pages 3197-3201
K. A. High, Richard Azani, A. F. Fazekas, Z. A. Chee, and J. S. Blais

Abstract: A description is given of a micro-atomization interface (made from quartz tubes) which is fuelled by hydrogen and can operate with 100% aqueous mobile phases used in HPLC. The system was optimized for the detection of Cd (total and bound soluble) in mussels and animal tissues, using flow injection AAS, or for the determination of metallothionein-bound Cd (isoforms I and II) in horse kidney, using HPLC - AAS. The detection limit obtained for Cd in the flow injection mode was ~2.2 orders of magnitude lower than that obtained with a conventional flame AAS detector, and 27-fold lower than that obtained by a thermospray-enhanced flame AAS system . Similar detection limits were obtained for the determination of metallothionein-bound Cd in the HPLC - AAS mode. A flexible thermospray-microatomization interface providing a high signal/noise ratio for flow injection atomic absorption spectrometry (AAS) and HPLC-AAS was designed and optimized for the determination of soluble Cd and Cd-metallothioneins (MTs). The interface, built from inexpensive quartz tubes, Swagelok fittings and thermoelectric wires, comprised 4 compartments: (1) a thermospray inlet; (2) a premixing tube in which the vaporized mobile phase was homogeneously mixed with preheated H; (3) a combustion chamber in which the fuel/sample mixture was mixed with O and pyrolyzed; and (4) a quartz tube (vapors retainer) mounted in the AAS analysis beam. This approach proved to more efficient than conventional flame AAS detection, due to the fact that the H/O flame (1900-2000°C), which pyrolysis mol. interferents to transparent CO2 and water vapors, is positioned remotely from the AAS optical beam. In this configuration, spectral interferences which are usually observed in flame and graphite furnace atomization were essentially eliminated. In flow injection (FI) mode, the response to Cd was linear from the limit of detection (71 pg) to 6 ng. The interface was optimized for the FI anal. of centrifuged mussel extracts, before and after ultrafiltration of the bound-Cd fraction on a 1000 MW cutoff membrane. During FI analyzes of these crude samples, matrix effect reduced the sensitivity by 13.2%, requiring calibration by standards addition Nonspecific absorption signal was not observed In HPLC-AAS mode, matrix effects in Cd-MTs chromatography bands were negligible. Cd-MTs from horse kidneys and mussels were determined with estimated limits of detection of 10^-40 ng (as protein).
Cadmium HPLC Spectrophotometry Optimization Interface Speciation Interferences

"Certification Of Three Mussel Tissue Standard Reference Materials (SRM) For Methylmercury And Total Mercury Content"
Fresenius J. Anal. Chem. 1997 Volume 358, Issue 3 Pages 424-430
M. K. Donais, Rajananda Saraswati, Elizabeth Mackey, Rabia Demiralp, Barbara Porter, Mark Vangel, Mark Levenson, Vesna Mandic, Sabine Azemard, Milena Horvat, Karl May, Hendrik Emons, Stephen Wise

Abstract: Three mussel tissue SRM (SRM 1974a, SRM 2974 and SRM 2976) were certified for methylmercury and total Hg contents. The methylmercury contents were measured using three independent extraction and quantification procedures; (i) solid-liquid extraction under acidic conditions, clean-up by gel permeation chromatography and GC, (ii) saponification at 70°C, room temperature ethylation, pre-concentration, GC followed by pyrolysis cold vapor (CV)-AFS and (iii) steam distillation under acidic conditions, separation of inorganic Hg and organomercury by anion-exchange chromatography, UV irradiation and CV-AAS. The total Hg content was measured using four independent procedures; (1) microwave digestion and flow injection CV-AAS, (2) instrumental NAA, (3) acid digestion at 70°C, double Au trap amalgamation and CV-AFS and (4) acid digestion at 150°C, Au wire amalgamation and CV-AAS. The certified values (ng/g, dry-mass basis) for methylmercury (as Hg)/total Hg contents were 77.2/186 for SRM 1974a, 77.2/171 for SRM 2974 and 27.7/61 for SRM 2976.
Mercury Methylmercury ion Spectrophotometry Fluorescence GPC Sample preparation Neutron activation analysis Amalgamation Preconcentration Reference material Speciation Volatile generation Volatile generation

"Isolation Of A New Okadaic Acid Analog From Phytoplankton Implicated In Diarrhetic Shellfish Poisoning"
J. Chromatogr. A 1998 Volume 798, Issue 1-2 Pages 137-145
R. Draisci*, L. Giannetti, L. Lucentini, C. Marchiafava, K. J. James, A. G. Bishop, B. M. Healy and S. S. Kelly

Abstract: A new analog of okadaic acid (OA), the toxin mainly responsible for diarrhetic shellfish-poisoning (DSP) phenomena in Europe, has been isolated from toxic phytoplankton (Dinophysis acuta) collected in Irish waters. Fluorimetric LC analyzes of the extracts of bulk phytoplankton samples using derivatization with 9-anthryldiazomethane (ADAM) showed a complex toxin profile, with peaks corresponding to OA and dinophysistoxin-2 (DTX-2) as well as a third unidentified compound. This minor unidentified component was isolated by chromatography techniques such as normal-phase chromatography, gel permeation on Sephadex, solid phase extraction and reversed-phase sepns. Ion-spray mass spectrometry (MS) was used for structural investigation on this compound due to the very small amt. of isolated material. Flow injection analysis (FIA)-MS of the isolated compound gavepositive-ion mass spectrum dominated by the protonated molecule, [M+H]+, at signal m/z 805, whereas the deprotonated mol. [M-H]- was observed in the negative-ion spectrum at signal m/z 803, thus indicating the mol. wt. of 804 for the new toxin, the same as OA and its known isomers, DTX-2 and DTX-2B. Collision-induced dissociation (CID) as obtained by positive and negative tandem mass spectrometry (MS-MS) showed a fragmentation pattern for the new compound which was very similar to that of OA, DTX-2 and DTX-2B. Ion-spray micro-LC-MS of a mixture containing the compound under investigation together with OA analogs showed the compound eluted after OA, DTX-2, DTX-2B and before DTX-1. All the chromatography and mass spectrometric data indicated the compound to be another OA isomer and it was therefore coded DTX-2C. To the best of our knowledge this is the first report on the isolation of a new compound related to DSP toxins from natural communities of toxic phytoplankton.
Okadaic acid derivative Mass spectrometry

"Optimized Microwave Digestion Procedure For Cadmium Analysis Of Mussel Samples"
Analusis 1998 Volume 26, Issue 7 Pages 261-263
M.C. Yebra and M.F. Enríquez

Abstract: A simple and rapid acid sample digestion method by microwave heating in high-pressure teflon bombs is reported for the determination of cadmium in mussels by flame atomic absorption spectrometry (FAAS) coupled online with a flow injection pre-concentration system. Tests concerning the digestion time, the power of the microwaves and the amt. of nitric acid were studied with the National Research Council of Canada lobster hepatopancreas marine (Tort-1) as certified reference material. Using 2 min of digestion time and 2 mL of nitric acid, the complete dissolution of 0.2 g of freeze-dried sample is possible. The anal. results, obtained with calibration graph as well as by the standard addition method, were agreed well with the certified value of the reference material. This procedure was applied to the determination of cadmium in mussel samples from estuaries in Galicia, Spain.
Cadmium Sample preparation Spectrophotometry Reference material Preconcentration Standard additions calibration

"Determination Of Saxitoxin In Preserved Mussels By HPLC With Post-column Derivatization And Fluorescence Detection"
Dtsch. Lebensm. Rundsch. 1987 Volume 83, Issue 12 Pages 379-381
Luckas, B.

Abstract: Homogenized canned mussels were de-fatted by heating with 0.15N-HCl. The mixture was filtered, the pH of the filtrate was adjusted to 5.2 with 0.45N-KOH and the solution was filtered and cleaned up on a column of anion-exchange resin of pH 5.2. Saxitoxin was eluted with 0.75N-H2SO4. The eluate was analyzed on a column of Nucleosil 7-C8 with aqueous formic acid, adjusted to pH 6.4 with NaOH, as mobile phase (1.0 mL min-1). Post-column derivatization was by treatment of the eluate with 10 mM H5IO6, followed by aqueous 1.2N-NH3 and 1.2N-H2SO4. Fluorimetric detection was at 390 nm (excitation at 340 nm).
Saxitoxin HPLC Fluorescence Post-column derivatization

"Paralytic Shellfish Poison Reference Materials: An Intercomparison Of Methods For The Determination Of Saxitoxin"
Food Addit. Contam. 1994 Volume 11, Issue 1 Pages 39-56
van Egmond HP, van den Top HJ, Paulsch WE, Goenaga X, Vieytes MR

Abstract: Saxitoxin (I) solution and crude mussel extracts were analyzed for I in a intercomparison study by 18 laboratories. Methods used involved HPLC with pre-column derivatization, HPLC with post-column derivatization, two other HPLC methods and ELISA. References for and brief details of the methods are given. Comparison of the methods and the results obtained revealed that all the methods were adequate for the determination of I in solution in the absence of interfering substances; the RSD was 33% at the 0.5 µg/ml level. Three of the HPLC methods were able to determine I in paralytic shellfish poison-positive mussel extract. The RSD of all HPLC results was 53% at the 1.5 mg/kg of shell-fish level and recoveries were 59-173%. The ELISA method grossly overestimated the I content in the mussel extract. The feasibility is demonstrated of preparing a homogeneous batch of ampouled mussel extracts (RSD of 3.5% at a I concentration of 1.5 mg/kg of shellfish), sufficiently stable for at least 4 months of storage at 4 and 20°C. Analytical problems encountered during the study are discussed.
Saxitoxin HPLC Interferences Pre-column derivatization