PERFORMANCE OF INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC METHODS USED IN THE DETERMINATION OF TRACE-ELEMENTS IN SURFACE WATERS IN HYDROGEOCHEMICAL SURVEYS

The capability of ICP-MS in determining trace and ultra-trace elements at their natural concentrations in stream and lake waters is evaluate d. The need to preconcentrate trace elements such as the first-row tra nsition elements and REEs is demonstrated and figures of merit given f or the chelation method employing the iminodiacetate resin, MetPac CC- 1. For example, chelaton results in method detection limits of 0.1-1 n g 1(-1) for Cd, U and REEs, and improves precision of their measuremen t 2-5 fold at low ng ml(-1) levels. Long-term quality control data for in-house and international standard water samples (SLRS-2, SLEW-1, CA SS-2, NASS-3 and 1643C) are presented, for both direct and chelation I CP-MS. Detection limits of 2-3 ng l(-1) are achieved for Ri, Sb,Se and Te by HG-ICP-MS and held duplicate data show precision generally of t he order of 10-20% RSD at levels below 100 ng l(-1). Considerations wi th respect to filtration and preservation protocols for hydrogeochemic al surveys are discussed. Field and laboratory (i.e., analytical) dupl icate data indicate good precision for trace and ultra-trace elements, averaging 13% RSD across all the elements determined.