Potential and limitations of capillary electrophoresis inductively coupled plasma mass spectrometry

Abstract

The hyphenation interface of CE to ICP-MS was characterised with respect to capillary position, gas flow rates and positioning of the total interface to the ICP-MS system. It turned out that absolutely optimised and reproducible operation is possible when all variable parameters are adjustable by micrometer screws. Analysis of a laboratory reference sample gave identical results (detection limit, element concentration, time of detection) after each set-up of the system during several years. After optimising the interface, the potential of the hyphenated system was elucidated. The hyphenated system was characterised by high separation capabilities, low detection limits and a broad field of application. Here, application was extended especially to iodine speciation. Detection limits of 0.04-1.2 µg L ^–1 , depending on the specific iodine species, were achieved. As the operation of the hyphenated system was totally reproducible according to micrometer screw drives, possible problems were found to be not typically ‘hyphenation problems’, but problems of capillary interactions and distorted separation. Wrong CE conditions were demonstrated to result in sample sticking to the capillary wall, lack of separation/focusing or decreased species stability. These problems were demonstrated by means of Sb speciation.