Determination of vanadium, chromium, arsenic, selenium and molybdenum in river and lake-water samples by nitrogen microwave-induced plasma mass spectrometry

The determination of V, Cr, As, Se and Mo at ultra-trace levels in river an d lake-water samples was carried out using a nitrogen microwave-induced pla sma mass spectrometer (N2MIP-MS), Spectral interferences caused by a matrix , such as Na, Ca, Cl, P and S, were examined. As a results, the (N2Na+)-N-1 4-Na-23 ion was produced at m/z = 51 in the mass spectrum, which interfered with a measurement of vanadium. However, it was found that the (N2Na+)-N-1 4-Na-23 ion intensity decreased with an increase in the microwave power of the nitrogen plasma. Therefore, the microwave power was set to be 1.3 kW. V anadium in river and lake-water samples was able to be determined after the samples were only diluted by 5-10 fold with pure water. The proposed metho d was applied to the determination of V, Cr, As, Se and Mo in standard refe rence materials (River Water Reference Material for Trace metals; NRC . CNR C SLRS-4, Certified Reference Material of Riverine Water; JAC 0032) and ter restrial water samples. The analytical results of standard reference materi als were in good agreement with the certified or reported values. The detec tion limits (3 sigma) were 0.3 ng/l for V, 0.2 ng/l for Cr, 8.3 ng/l for As , 26 ng/l for Se and 4.0 ng/l Mo.