ANALYSIS OF RIVER WATER BY ICP-MS WITH ONLINE PRECONCENTRATION USING FLOW-INJECTION

A flow injection manifold is described for on-line preconcentration of several elements and their determination by inductively coupled plasm a mass spectrometry. It incorporates a cleaning column on the buffer l ine to remove trace contaminants from the buffer prior to its mixing w ith the sample. A 2 M HNO3 eluent is also used to allow the determinat ion of elements which suffer from spectroscopic interferences from Cl- containing compounds. The preconcentration, factor can easily be chang ed by simply modifying the sample loading time (i.e. the amount of tim e the sample is pumped through the analytical column). A 30-fold preco ncentration (using 1.5 ml of sample and 50 mu l of eluent) was used fo r the analysis of certified river water SLRS-2. Under these conditions , the sample throughput was about 20 samples/h. Results in good agreem ent with the certified values were obtained for V, Co, Cd and Pb by th e method of standard additions, and for V, Co, Cd and Sb by external c alibration. Both calibration strategies provided results of similar ac curacy and precision, but the latter is far less time-consuming. On th e other hand, the trace determination of ubiquitous elements such as Z n is still precluded by a high blank.