Coupling of capillary zone electrophoresis to mass spectrometry (MS and MS/MS) via a nanoelectrospray interface for the characterisation of some beta-agonists

Capillary zone electrophoresis (CZE) was coupled to mass spectrometry (MS) via nanoelectrospray interface (nESI), using conductively coated tips (8 mu m orifice) butted to the end of a fused-silica capillary. The CZE/nESI-MS system was carefully optimised to achieve a stable operation of the arrange ment in order to run also MS/MS experiments. Mixtures of beta-agonists were successfully separated using 5 mmol/L ammonium acetate in 80% MeOH as a bu ffer. The limit of detection was 500 attomole of a substance injected. The system was also investigated from the point of view Of quantification Of th e substances. Careful measures:were taken to avoid any systematic errors (e vaporative loss during the electrokinetic injection and reduction of migrat ion times due to the electrospray pull during the CE run). The data show th at the response of a mass spectrometric detector in the low-femtomole range not only depends on the concentration of the, analyte but also on the prop erties of the nanoelectrospray process itself, that is why the linearity of the response can be compromised. Copyright (C) 1999 John Wiley & Sons;Ltd.