Arsenic Speciation in Water and Human Urine by HPLC–ICP-MS and HPLC–MO–HG-AAS

Arsenite, arsenate, monomethylarsonate, dimethylarsinate, arsenobetaine, and arsenocholine have been successfully separated in one chromatographic run in a mixed mode column, Spherisorb ODS/NH2, using 5.0 mmol liter−1phosphate buffer at pH 5.0 as mobile phase and final detection by inductively coupled plasma mass spectrometry (ICP-MS) or microwave-assisted oven (MO) coupled with hydride generation atomic absorption spectrometry (HG-AAS). The detection limits achieved with the HPLC–ICP-MS coupling (0.04–0.28 ng) were about 20 times lower than those achieved by HPLC–MO–HG-AAS, which makes it suitable for determining these species at their naturally occurring concentration levels. The chloride present in the samples was chromatographically separated from the arsenic species, and the interferent signal from the40Ar35Cl formed on the ICP-MS system was insignificant. The proposed methods were successfully applied to the determination of six arsenic species in water and urine (after previous cleanup of the sample).