MEASUREMENT OF VANADIUM, NICKEL, AND ARSENIC IN SEAWATER AND URINE REFERENCE MATERIALS BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH CRYOGENIC DESOLVATION

Addition of a small dose (2%) of H-2 to the aerosol gas flow enhanced analyte signals by a factor of 2-3, which compensated for the loss of analyte signal that accompanied earlier efforts at cryogenic desolvation with inductively coupled plasma mass spectrometry (ICP-MS). Vanadium, nickel, and arsenic at microgram per liter levels in urine, river, and seawater reference materials were determined. The polyatomic ions ClO+, CaO+, and ArCl+, which normally cause severe overlap interferences for these elements, were attenuated to manageable levels by cryogenic desolvation. The samples were simply diluted with 1% HNO3 so that the chloride could be removed as HCl. The analytical results obtained for these standard reference materials agreed closely with the certified or recommended values. The detection limit ranges (3sigma) obtained were 10-1000 ng L-1 for V, 0.03-20 mug L-1 for Ni, and 4-7000 ng L-1 for As in the original samples. The samples were introduced by flow injection to minimize clogging of the sampling orifice.