COMPARISON OF FLUOROMETRIC AND INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY DETECTION SYSTEMS FOR THE DETERMINATION OF ALUMINUM SPECIES IN WATERS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

The comparison of element-specific detection using HPLC-ICP-MS with an established HPLC-fluorimetric method for aluminium speciation in wate rs is described. This comparison allowed the identification of some pr oblems with a fluorimetric detection method based around 8-hydroxyquin oline-5-sulfonic acid, particularly its comparatively poor selectivity and Al-species dependent response factors. The power of ICP-MS as a d etector for HPLC systems is demonstrated by the simultaneous detection of Al, Mg, Zn, and Fe. The increased selectivity of ICP-MS over molec ular fluorescence is shown in the reliable quantification of Al3+ and AlF2+ in a range of tap and natural water samples. The fluorimetric te chnique exhibited varying response factors to different aluminium spec ies while the specific detector gave constant signals. Both techniques provided similar values for the 'free' Al3+ fraction in a variety of natural waters but systematic differences were obtained in the quantif ication of the AlF2+ fraction. Problems with the ICP-MS detection meth od for Al-speciation analysis such as ion interferences and salt conce ntration of the mobile phase are commented upon.