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SPECIATION NEUTRON ACTIVATION ANALYSIS FOR ARSENIC IN MARINE FISH

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					                           ANALYTICAL METHODS - VERBAL

  SPECIATION NEUTRON ACTIVATION ANALYSIS FOR ARSENIC IN
                      MARINE FISH

                              A. Chatt and Youqing Shi
                 SLOWPOKE-2 Facility, Trace Analysis Research Centre
                    Department of Chemistry, Dalhousie University
                           Halifax, Nova Scotia, B3H 4J3
                                      Canada


     Neutron activation analysis (NAA), in its various forms such as instrumental NAA,
preconcentration NAA and radiochemical NAA, is well known for its ability to
simultaneously measure multielement concentrations. These techniques are generally
employed for the determination of total element concentrations. Neutron activation
methods involving chemical separations prior to irradiations can also be developed to
determine the species of an element. The technique can then be called speciation NAA
(SNAA). Since the toxicity of an element depends significantly on its physico-chemical
form, there is an increasing interest in studying elemental speciation. Several analytical
techniques can be used for this purpose. However, SNAA offers a number of
advantages over other methods; these include multielement specificity, excellent
accuracy, high precision, improved sensitivity, small sample size, and qualitative as
well as quantitative analysis. We have developed SNAA methods for assaying various
arsenic species, namely As(III), As(V), dimethylarsonic acid (DMA), monomethylarsinic
acid (MMA), arsenobetaine (AsB), organically bound arsenic (OBAs), and lipid-soluble
arsenic (LSAs) in marine fish samples. The method involves extraction by a methanol-
MIBK-water system, cation exchange chromatography, and HPLC followed by NAA.
The detection limits for various arsenic species are around 20 ng g-1 of fish under the
experimental conditions of 2-h irradiation in a neutron flux of 5x1011 cm-2 s-1 at the
Dalhousie University SLOWPOKE-2 facility. Details of the methods and results will be
presented.




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posted:8/17/2011
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