ONLINE REMOVAL OF INTERFERENCES IN THE ANALYSIS OF BIOLOGICAL-MATERIALS BY FLOW-INJECTION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

A method of matrix elimination was developed that facilitates the interference-free determination of the trace metals vanadium, manganese, copper, zinc, cadmium and lead in biological matrices by inductively coupled plasma mass spectrometry. The method involves chelation of the analytes onto an iminodiacetate-based resin in a microcolumn with simultaneous matrix removal. The analytes are then eluted into the spectrometer with 3 mol l-1 nitric acid using a flow injection procedure. Analysis of certified reference materials yielded results in reasonable agreement with the certified values. Recovery tests showed close to 100% recoveries for manganese, copper, cadmium and lead, 90% recovery for vanadium and 85% recovery for zinc. The limit of detection (3sigma) for these analytes using a 175 mul sample loop ranged from 0.6 to 9.9 ng ml-1 i.e., from 75 to 1800 pg or from 50 to 825 mug kg-1 dry mass of sample. The same chromatographic system was applied to chromium determinations, but proved unsuccessful.