In this paper the importance of reagent water quality for toxic element environmental analyses is discussed, and the suitability of fresh ultrapure water produced using Merck water purification systems for ICP-OES and ICP-MS trace element analyses in environmental laboratories is demonstrated.
Key words or phrases
Trace elements, metals, toxic elements, ICP-MS, ICP-OES, contamination, BEC, LOD, water quality, interferences
Introduction and Water Quality Requirements
Dramatic improvement in the sensitivity of analytical instruments over the last decades has changed our understanding of environmental contamination and hazardous effects of metals such as Be, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Sb, Ba, Hg, Tl, and Pb. This has resulted in a number of regulations and guidelines that establish the maximum acceptable or recommendable concentrations of toxic metals in drinking water,1 marine water,2 and wastewater.3 The requirements instituted by authorities consequently have resulted in a growing need for toxic metal monitoring in environmental laboratories where spectrometry techniques are standard instrumentation recommended for the determination of trace elements.4,5 The preponderant role of ICP-MS and ICP-OES in the detection of traces of toxic metallic elements in environmental analyses of water and soil has led to higher quality requirements for ultrapure water, which is the most frequently used reagent in ICP-MS and ICP-OES analyses. In particular, ultrapure water is used as the reagent blank, for sample and standard preparation, and for instrument and sample container cleaning (Figure 1). Therefore, the ultrapure water must be free of metals to preserve analytical instruments from contamination and to avoid interferences with analyzed elements, in order to ensure the accuracy and precision of measurements.