Comparison of electrothermal atomic absorption spectrometry, quadrupole inductively coupled plasma mass spectrometry and double-focusing sector field inductively coupled plasma mass spectrometry for the determination of aluminium in human serum

Abstract

A detailed examination of the performance of ICP-MS, using both a quadrupole-based and a double-focusing sector field instrument, for the determination of Al in human serum was carried out and the results were compared with those obtained by ETAAS as the reference technique for this type of analysis. Both ICP-MS techniques were compared in terms of observed matrix effects, spectral interferences and overall analytical performance. The results showed that ICP-MS was superior to ETAAS in terms of detection power [detection limits of 0.35 µg l–1 using sector field ICP-MS and 0.85 µg l–1 with quadrupole ICP-MS as compared with 2 µg l–1 for ETAAS determinations of Al in serum (3σ)]. Negligible matrix effects were observed using the quadrupole instrument for serum diluted 1+4 with water. However, the double-focusing instrument showed matrix effects even for a 1+9 dilution of the serum. In any case, such matrix effects could be eliminated by the use of Be and Sc as internal standards. Spectral interferences at m/z=27 in the serum matrix were observed by using the sector field instrument at a resolution of 3000. The analytical methods developed were applied to the determination of Al in reference serum samples with satisfactory results. However, Al serum determination in healthy subjects (n=20) showed that typical basal Al levels in serum required high resolution and, as a rule, were below the detection limit of sector field ICP-MS (i.e., less than 0.35 µg l–1).