Speciation of arsenic compounds in human urine by HPLC/hexapole collision cell ICP-MS

Abstract

The analytical conditions for the simultaneous determination of arsenic(As) compounds in human urine were examined using high-performance liquid chromatography (HPLC) with an ion-exchange column combined with a hexapole collision cell inductively coupled plasma mass spectrometer. The addition of 0.1 mM EDTA to the mobile phase of HPLC (a mixture of 10 mM NH4NO3 and 0.05% HNO3, pH 3.1) was necessary for good reproducibility of the peaks. The five As species {As(V), monomethylarsonic (MMA), dimethylarsinic (DMA), As(III), and arsenobetain (AB)} were separated within 14 min, however, arsenocholine(AC), trimethylarsine oxide (TMAO) and tetramethylarsonium (TeMA) were not individually separated but eluted together at about 40 min of retention time. This method was applied to urine samples from 8 male Japanese. Although As(V), MMA, DMA, and AB were detected in all urine samples, the relative amounts of these compounds were different depending on the person. The order of concentrations of arsenic compounds in urine from 4 person were AB>DMA>MMA>As(V), but those in the other samples were AB = DMA or AB<DMA, suggesting the individual difference in the eating habits of sea foods.