Determination of U and major elements in Lake Biwa water and its inflow river water by ICP/three dimensional quadrupole mass spectrometer

Abstract

An analytical method for the rapid determination of major elements (Na, K, Ca, Mg) and U at the ultra-trace level in river and lake water samples was developed by ICP/three dimensional quadrupole mass spectrometer (ICP/3DQMS). The optimum analytical scanning condition of ICP/3DQMS, the dependency of the buffer gas pressure at 3DQMS on the ion signal intensity, and the effect of the matrix-element concentration on U at the trace level were investigated. As a result, the detection limit (3σ) of U by this method was 0.7 ng/l. The proposed method was applied to the determination of Na, K, Ca, Mg and U in Riverine water (NRC·CNRC SLRS-4) and Lake Biwa water as well as the 13 rivers water of flowing into the lake. The analytical result of U in Riverine water was in good agreement with the certified value. The analytical results of Na, K, Ca and Mg in Lake Biwa water and the water of 13 rivers flowing into the lake were in good agreement with the values obtained by ICP-OES. The concentration of Ca in the water of 13 rivers flowing into the lake reflected the surrounding geological features. The uranium concentration was high at the north eastern district of Lake Biwa. The average contents of the Lake Biwa surface water were 8.3 mg/l for Na, 2.28 mg/l for Mg, 1.48 mg/l for K, 12.1 mg/l for Ca and 22.0 ng/l for U. The vertical distribution of U in lake Biwa water changed with the water column depth.