CAPILLARY ZONE ELECTROPHORESIS-ELECTROSPRAY MASS-SPECTROMETRY AT SUBMICROLITER FLOW-RATES - PRACTICAL CONSIDERATIONS AND ANALYTICAL PERFORMANCE

A novel method for the production of coated capillaries for capillary zone electrophoresis-electrospray mass spectrometry (CZE-ESMS), operat ing at 100-200 nL/min now rates is described. Electrophoretic conditio ns conducive to the simultaneous operation of ESMS were investigated f or microsprayers of different inner diameters. The ruggedness and reli ability of the CZE columns with microsprayers of 20 mu m i.d. were inv estigated over 6 h of uninterrupted operation. Detection limits in the order of 0.1-5 fmol were obtained for peptide standards of molecular masses ranging from 500 to 2500 Da, and sensitivity was similar to 10 times higher than that achieved using the more conventional sheath now CZE-ESMS interface. Such enhancement of signal detectability provided distinct advantages for on-fine line tandem mass spectrometric analys es whereby structurally informative MS-PUIS spectra were obtained usin g femtomole loadings of peptides and glycopeptides from ovalbumin dige sts.