ELEMENTAL SPECIATION BY ANION-EXCHANGE AND SIZE-EXCLUSION CHROMATOGRAPHY WITH DETECTION BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH DIRECT-INJECTION NEBULIZATION

A direct injection nebulizer (DIN) is used with packed microcolumns for anion chromatography (AC) and size exclusion chromatography (SEC). Two Se species (SeO32- and SeO42-) are separated by AC with detection limits of 15 pg of Se. The isotope ratio Se-74/Se-78 can be measured with a relative standard deviation of 0.5 % on 25 ng of each Se species during the actual chromatographic separation. Proteins in human serum are separated by SEC without sample pretreatment. The metals present in each molecular weight fraction are determined by ICP-MS with detection limits of 0.5-3 pg of metal. These absolute detection limits are 1-2 orders of magnitude better than those obtained with conventional nebulizers.