Multi-elemental trace analysis of human serum by double-focusing ICP-MS

A method is described for the determination of a selected range of trace and ultratrace elements in human serum, using a double-focusing ICP-MS instrument (ELEMENT, Finnigan-MAT). Serum samples were diluted 1+4 with ultrapure water and addition of Sc, Ga, Y and Tl as internal standards, to a final concentration of 10 mu g L-1, was used for matrix interference correction. Low and medium resolution scans were performed on the instrument for the analyses, the first scan, at m/Delta m = 300, for the determination of Rb, Sr, Mo, Cd, Pb and U and the second scan, at m/Delta m = 3000, for the determination of those elements subject to interference at low resolution: Al, Ca, Cr, Mn, Fe, Co, Cu, Zn and Se. A SRM, 1598 Inorganic Constituents in Bovine Serum (NIST), was analysed for validation of the multi-element analysis method. Good agreement was achieved between the found levels and the certified values. The method was also applied to the multi-analysis of trace elements in serum samples from healthy subjects and from uraemic patients. Preliminary experiments carried out with both quadrupole and double-focusing ICP-MS instruments proved to be invaluable for the study of spectral and non-spectral interferences in ICP-MS detection.