Performance of inductively coupled plasma mass spectrometric methods used in the determination of trace elements in surface waters in hydrogeochemical surveys

Abstract

The capability of ICP-MS in determining trace and ultra-trace elements at their natural concentrations in stream and lake waters is evaluated. The need to preconcentrate trace elements such as the first-row transition elements and REEs is demonstrated and figures of merit given for the chelation method employing the iminodiacetate resin, MetPac CC-1. For example, chelaton results in method detection limits of 0.1–1 ng l^–1 for Cd, U and REEs, and improves precision of their measurement 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, CASS-2, NASS-3 and 1643C) are presented for both direct and chelation ICP-MS. Detection limits of 2–3 ng l^–1 are achieved for Bi, Sb, Se and Te by HG-ICP-MS and field duplicate data show precision generally of the order of 10–20% RSD at levels below 100 ng l^–1. Considerations with respect to filtration and preservation protocols for hydrogeochemical surveys are discussed. Field and laboratory (i.e., analytical) duplicate data indicate good precision for trace and ultra-trace elements, averaging 13% RSD across all the elements determined.