Assessment of ICP-MS for routine multielement analysis of soil samples in environmental trace element studies

Summary The suitability of inductively coupled plasma mass spectrometry (ICP-MS) following acid digestion of samples was evaluated for the routine determination of trace elements in contaminated and control soil samples. The contaminated samples were collected near an expressway and two secondary lead smelters in Toronto. All samples were acid digested in pressure vessels using a combination of reagents including hydrofluoric and perchloric acids. Consequently, the total amount of the elements (Pb, Sb, Cd, As, Mn, Mo and Cr) were being determined. In the case of lead direct comparison and isotope dilutional MS procedures were compared. Standard Reference Materials (SRM's) were run to allow an assessment of precision and accuracy. Isotope ratios were determined in the contaminated samples to evaluate whether this approach could be used, routinely, to determine the source of the lead. National Bureau of standards (NBS) 981 isotope ratio reference sample was used to evaluate the accuracy of the lead isotopic ratio data.Generally, the results obtained for the total amounts of the elements in the SRM's were in satisfactory agreement with the certified values. The measured isotopic ratios had a small positive bias compared to the NBS certified values. Isotope dilution MS values for Pb were superior in accuracy and precision to those obtained by direct comparison calibration. At the present state-of-the-art, routine isotope ratio measurements are not good enough for source typing in a study such as this. Values obtained in the present investigation compared well with those reported in a 1974 study of same areas.