Comparison of the performance of FI-ICP-MS and FI-ETV-ICP-MS systems for the determination of trace elements in sea water

The performance of two flow injection systems (FI) for on line separation a nd pre-concentration of Cu, Cd, Pb, Bi, Au, Ag, As(III) and Se(IV) in sea w ater and determination by inductively coupled plasma mass spectrometry are compared. One system is coupled to the nebulizer of the spectrometer while the other one is coupled to an electrothermal vaporizer also coupled to the same spectrometer. The matrix separation and analyte pre-concentration are accomplished by retention of the analytes complexed with the ammonium salt of O,O-diethyl dithiophosphate on Cls immobilized on silica in a column co upled directly to the pneumatic nebulizer or to the auto-sampler arm of an electrothermal vaporizer. The eluate is on line diluted with water and intr oduced directly to the pneumatic nebulizer or vaporized after bring automat ically injected into the graphite tube, prior to the vaporization of the an alytes. The conditions for the complexation-separation and elution were opt imized. The accuracy was checked by the analysis of two certified sea water s, CASS-3 and NASS-4, from the National Research Council of Canada. Only As (III) could not be determined in the sea water medium. The recoveries for t he non-certified elements were in the range 90-110%. The relative standard deviation ale below 10% while the sampling frequencies are in the range 21- 22 h(-1) for both systems. (C) 2001 Elsevier Science B.V. All rights reserv ed.