Determination of Vanadium (IV) and (V) in Southern Nevada Groundwater by Ion Chromatography-Inductively Coupled Plasma Mass Spectrometry

A rapid method is presented for measuring V(IV) and V(V) in groundwater, without preconcentration or complexing agents, using direct injection of the water samples (which were collected under an argon atmosphere) into an ion chromatograph-inductively coupled plasma mass spectrometer (ICPMS). The mobile phase is 1.5% v/v nitric acid, which minimizes the buildup of solids in the ultrasonic nebulizer, the torch, and on the entrance cones of the ICPMS a problem with methods using organic complexing agents and inorganic salts. The result is much less instrument downtime for cleaning the affected parts. Limits of detection are 0.02 g L -1 for V(IV) and 0.06 g L -1 for V(V). The pentavalent form of vanadium represents 98% to 99% of the vanadium in these Southern Nevada groundwater samples and ranges from 3.7±0.1 g L -1 to 82.1±0.5 g L -1 . The remaining few percent is V(IV). Total vanadium was determined by ICPMS for a mass-balance comparison.