ACCURATE DETERMINATION OF ELEMENT SPECIES BY ONLINE COUPLING OF CHROMATOGRAPHIC SYSTEMS WITH ICP-MS USING ISOTOPE-DILUTION TECHNIQUE

The instrumental design for coupling different liquid chromatographic systems such as ion, reversed phase, and size exclusion chromatography as well as capillary gas chromatography, with ICP-MS for the determin ation of element species is described. For accurate analyses obtaining 'real time' concentrations of chromatographic peaks, the isotope dilu tion mass spectrometric (IDMS) technique is applied. Two different spi king modes are possible, one using species-specific and another one us ing species-unspecific spike solutions of isotope-enriched labelled co mpounds. The species-specific mode is only possible for element specie s well defined in their structure and composition, for example iodate or selenite, whereas the species-unspecific mode must be applied in al l cases where the structure and composition of the species is unknown, for example, for metal complexes with humic substances. For accurate determinations by the isotope dilution technique the mass discriminati on effect must also be taken into account. Iodate, iodide and organoio dine species, including those of humic substances, have been analysed in mineral, drinking and environmental water samples by coupling diffe rent liquid chromatographic methods with ICP-IDMS. Heavy metal complex es with humic substances in water samples of different origin have bee n characterized by size exclusion/ICP-IDMS. The possibilities of deter mining different environmental selenium species are discussed and the results for the analysis of selenite and selenate, which has been carr ied out by GC/ICP-IDMS after converting these species into a volatile piazselenol compound, are presented. (C) 1998 Elsevier Science B.V.