SPECIATION OF CHROMIUM BY DIRECT COUPLING OF ION-EXCHANGE CHROMATOGRAPHY WITH INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

inductively coupled plasma mass spectrometry (ICP-MS) for the element speciation of chromium. Hydraulic high pressure nebulization was used for sample introduction with high aerosol efficiency. It was the parti cular aim of this work to exclusively use nitric acid for elution in o rder to reduce interferences in ICP-MS. Therefore, an anion exchange p recolumn IonPac-AG5 (Dionex, Idstein, Germany) with a length of 50 mm and an id of 4 mm has been operated as a mixed-mode column, which Show s cation exchange capabilities too. The column was operated at a flow rate of 1.2 ml min(-1) and samples were injected by use of a sample lo op with a volume of 100 mu l. Both Cr-VI anions and Cr-III cations cou ld be retained on the column, and optimum results concerning. chromato graphic and mass spectrometric conditions were finally achieved with d iscontinuous elution in two steps by injection of 0.3 M (pH 0.5) HNO3 for Cr-VI add subsequently of 1.0 M (pH 0) HNO3 for Crm, Detection lim its just above 0.1 mu g l(-1) could be realized.