Exact mass determination of narrow electrophoretic peaks using an orthogonal acceleration time-of-flight mass spectrometer

High efficiency electrically driven separation techniques, such as capillar y zone electrophoresis (CZE) and capillary electrochromatography (CEC), yie ld narrow peak widths of the order of a few seconds. Scanning instruments m ay have difficulty in obtaining sufficient data points across such narrow p eaks (although the use of selected ion monitoring (SIM) mode may overcome t his). Orthogonal acceleration time-of-flight ((oa-TOF)) mass analysers have an inherent ability for fast acquisition rates allowing a high number of d ata points (for example 10 spectra s(-1)) to be collected across a narrow p eak and are capable of operation at resolutions in the region of 5000 full width half maxims (FWHM), This enables spectral data to be measured with ac curacies greater than 5 ppm, allowing the molecular formula to be predicted / confirmed. We have investigated the use of an oa-TOF mass analyser coupl ed to CZE, The on-line separation of a drug substance and related impuritie s has been achieved. Copyright (C) 1999 John Wiley & Sons, Ltd.