EVALUATION OF MULTIELEMENT CAPABILITY OF ICP-MS

Results obtained from an EPA multilaboratory study of the inductively coupled plasma mass spectrometry (ICP-MS) method are compared with results for graphite furnace atomic absorption spectrometry (GFAAS) for the elements As, Pb, Se, and Tl, and with results from inductively coupled plasma atomic emission spectrometry (ICP-AES) for the elements Al, Sb, Ba, Be, Cd, Ca, Cr, Co, Cu, Fe, Mg, Mn, Ni, K, Ag, Na, V, and Zn. A representative matrix set of 6 waters, 10 soils, and a predigested group of 18 samples was used. A complete two-way analysis of variance was carried out. The statistical study indicates that analytical concentrations averaged over all ICP-MS laboratories agree with those of the reference methods for a number of the elements in each matrix set. There is highly significant variation among laboratories, but replicate determinations within laboratories are satisfactory. The methods show poor agreement with reference values for samples with low analyte concentrations. Detection capabilities for ICP-MS are greater for most elements, and the proportion of outliers is comparable. Moreover, a separate analysis of variance comparing the two types of ICP-MS instruments indicates disagreement of results for some of the elements.