Determination of cadmium in environmental and biological reference materials using isotope dilution analysis with a double focusing ICP-MS : a comparison with quadrupole ICP-MS

• Published in: Journal of analytical atomic spectrometry 1999, Vol.14 (9), p.1467-1473
• Main Authors: VALLES MOTA, J. P, RUIZ ENCINAR, J, FERNANDEZ DE LA CAMPA, M. R, GARCIA ALONSO, J. I, SANZ-MEDEL, A
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/a901753d

The performance of a double focusing (DF) sector field inductively coupled plasma mass spectrometer (ICP-MS) (Element, Finnigan MAT) for the isotope dilution-ICP-MS determination of cadmium was compared with that of a quadrupole-based instrument (HP4500, Hewlett Packard). Operating conditions and various data acquisition parameters (for example, number of scans, dwell time and mass window) were optimized. Systematic errors, such as the detector dead-time, mass bias effects and spectral interferences were easily corrected. The isotope ratio precision for both instruments was typically 0.2 to 0.3 per cent. In the case of the DF-ICP-MS, the precision could be reduced by increasing the number of scans, reaching 0.08 per cent for the maximal number of scans (2500) , although this also increased the analysis time. In addition, the sensitivity of DF-ICP-MS at low resolution was better than for the quadrupole ICP-MS. Both instruments were successfully applied to the analysis of trace cadmium in the certified reference materials Urine NIST SRM-2670, Horse Kidney IAEA H-8, Lichens BCR TP-25, Riverine Water SLRS-3 and Marine Sediment PACS-1, using conventional and on-line flow ID modes. The sources of uncertainty were considered. There are 37 references.