Determination of total toxic arsenic species in human urine using hydride generation inductively coupled plasma mass spectrometry

In order to evaluate people's exposure to arsenic in drinking water, hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS), a simple and fast method, was developed to determine the total concentration of toxic arsenic species in the urine samples. Different factors affecting the hydride generation reactions were studied. It was found that under optimized conditions with 1% NaBH4, 0.2 M HCl and 0.05 M L-Cysteine, the toxic arsenic species were effectively separated from non-toxic species. In addition, it was discovered that inorganic and monomethylarsenic species have similar sensitivities with HG-ICP-MS detection, while dimethylarsenic species have slightly lower sensitivity. With this method, good linearity, repeatability and recovery were achieved along with the low detection limit of 6 ng L-1 (3 sigma). This HG-ICP-MS method was employed to analyze a NIST standard reference material, SRM2670a, as well as urine samples from subjects under an arsenic exposure and remediation study; the concentration of all toxic species determined by this method was in good agreement with that measured by IC-ICP-MS speciation. The results suggested this HG-ICP-MS method is better than an ICP-MS total arsenic measurement in evaluating people's exposure to inorganic arsenic in drinking water, because it can exclusively measure toxic arsenic species in urine, which come from inorganic arsenic exposure, with better sensitivity.