New sheathless interface for coupling capillary electrophoresis to electrospray mass spectrometry evaluated by the analysis of fatty acids and prostaglandins

A new interface for capillary electrophoresis electrospray ionization (CE-E SI) is presented. High voltage is applied at the outlet of the separation c apillary by a stainless steel tube, a so called liner, through which the ca pillary is led. A compensating current between the liquid and the liner is maintained by a natural liquid film, which is built up at the outer surface of the capillary end. Operable potential ranges for differently treated ca pillary ends have been examined. The liner has been evaluated for the analy sis of fatty acids and prostaglandins, all run with the ESI in the negative ionization mode. This simple stainless steel liner should fill the gap, wh ich has prevented CE-MS from being the successful tool, which it has the po tential for, namely fast and unattended measurements of analytes in the nM range in complex mixtures. (C) 1999 Elsevier Science BN. All rights reserve d.