| The speciation of trace arsenic has received particular attention in recent years. A combination of several chemical separation methods and neutron activation analysis (NAA) has been developed here for the speciation of arsenic.; An open-column cation exchange chromatographic method has been developed to separate dimethylarsinic acid (DMA) and arsenobetaine (AsB) from the anionic arsenic species including arsenite (As(III)), arsenate (As(V)) and monomethylarsonic acid (MMA). The method has been used as a group separation step in the speciation analysis schemes of water and seafood samples.; A solvent extraction-NAA method using ammonium pyrrolinedithiocarbamate (APDC) and 4-methyl-2-pentanone (MIBK) has been developed for the separation of As(III), As(V), Sb(III), Sb(V) and Se(IV). The acidity, aqueous-to-organic phase volume ratio, stability of the complexes, and potential interferences have been investigated.; A solid-phase extraction (SPE)-NAA method using dibenzyldithiocarbamate (DBDC) impregnated Amberlite XAD-4 resin has been developed for the determination of As(III) and Sb(III). The adsorption rate, adsorption isotherms, and various factors affecting the coating of DBDC on XAD-4 have been investigated.; A HPLC-NAA method using an anion exchange column and phosphate buffer has been developed for the determination of As(III), As(V), MMA, DMA, and AsB. A 10-mM phosphate buffer at pH 6.5 has been selected for the separation of AsB and DMA, and the same buffer at 75 mM and pH 5.5 has been used to separate As(III), MMA, and As(V).; The above methods have been successfully applied for the determination of As(III), As(V) MMA, DMA, AsB, and organically bound arsenic (OBAs) in water samples, and of As(III), As(V) MMA, DMA, AsB, lipid-soluble arsenic, and total arsenic in several fish samples. AsB has been found to be the predominate arsenic species in fish and As(V) in water. The precision and accuracy of the speciation methods have been found to be good. |
