CAPILLARY ELECTROPHORESIS COUPLED ONLINE WITH INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY FOR ELEMENTAL SPECIATION

A novel interface to connect a capillary electrophoresis (CE) system w ith an inductively coupled plasma mass spectrometric (ICPMS) detector is reported here. The interface was built using a direct injection neb ulizer (DIN) system. In this interface, the CE capillary was placed co ncentrically inside the fused-silica DIN sample introduction capillary . A makeup liquid was pumped at a now rate of 15 mu L/min into the fus ed-silica DIN sample transfer capillary via a connector. The makeup li quid flowing outside the CE capillary sewed two purposes: (a) it estab lished continuous and stable electrical contact at the exit (grounding ) terminus of the CE capillary, and (b) it allowed the DIN system to b e optimized independently of the CE system for efficient sample introd uction to the ICPMS system. The makeup liquid along with the liquid fr om the electroosmotic now generated inside the CE capillary was nebuli zed by the DIN system directly into the ICP torch. The CE/DIN-ICPMS sy stem was evaluated using test samples containing selected alkali, alka line-earth, and heavy metal ions, as well as selenium [Se(IV) and Se(V I)], and various inorganic and organic arsenic species. The preliminar y results show that the CE/DIN-ICPMS system can be used to determine m etal species at parts-per-trillion to parts-per-billion levels.