SPECIATION OF ARSENIC METABOLIC INTERMEDIATES IN HUMAN URINE BY HPLC AND HYDRIDE GENERATION ATOMIC FLUORESCENCE SPECTROMETRY

Biomethylation is the principal metabolic and detoxification pathway for inorganic arsenic in human. The end products of methylation are less toxic and more readily excreted through urine. The speciation of metabolites in urine is essential to a better understanding of arsenic metabolism, health effects and detoxification capacity of individuals exposed to arsenic through drinking water, food and environmental materials.

Speciation of inorganic and methylated arsenic in urine is an analytical challenge. We have developed a technique for separating and analysis of various arsenic species, such as, arsenite, arsenate, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in urine. The technique is based on chromatographic separation followed by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS). Arsenite (As^III) is found to be the major component in urine. The detection limit varies from 1.0—2.0 m/l for various species. The technique has been successfully applied to speciation of arsenic metabolite intermediates in urine samples collected from patients in Shibpur and Monohordi Upazila in Narshindi District in Bangladesh. The developmental work and the routine speciation has been carried out at the Exonics Technology Center, Dhaka.

Results from our findings from an arsenic affected area will be discussed. The technique permits us to carry out routine arsenic speciation in biological tissues, essential for toxicological and epidemiological studies.