Selective determination of toxicologically important arsenic species in urine by high-performance liquid chromatography–hydride generation atomic absorption spectrometry

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Abstract
In studies on arsenic exposure and its monitoring, a method for the selective determination of trivalent and pentavalent inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in urine was developed. The method is based on the ion-pair chromatographic separation of arsenic species and continuous hydride generation for the determination of arsenic in the chromatographic effluent by atomic absorption spectrometry. The chromatographic separation was completed within 4 min by using tetrabutylammonium ion in phosphate buffer as the ion-pairing agent and a C18 reversed-phase column. The detection limits were 1.0, 1.6, 1.2 and 4.7 µg dm–3 of arsenic for AsIII, AsV, MMA and DMA, respectively. These detection limits are not low enough to detect the lowest levels of these arsenic species in the urine of unexposed subjects. However, accurate measurement of the concentrations due to occupational exposure is easily achieved.