MODIFIED IONSPRAY INTERFACE FOR SUPERCRITICAL-FLUID CHROMATOGRAPHY MASS-SPECTROMETRY - INTERFACE DESIGN AND INITIAL RESULTS

A pneumatically assisted electrospray liquid chromatography/mass spect rometry interface has been modified for use with open-tubular supercri tical fluid chromatography (SPC). The modified interface houses the SF C flow restrictor within the spray device. A sheath-flow liquid of met hanal or methanol/water containing ammonium acetate flows coaxially to the restrictor, The addition of the sheath-flow liquid results in the ionization of analytes known to be in a neutral charge state during t he chromatographic separation. The sheath-how liquid also allows for t he independent operation of the chromatograph and the mass spectromete r. Both could be operated under optimum conditions. The operation of t he interface was optimized using a solution of poly(dimethylsiloxane) in CO, introduced by continuous infusion. We also report the applicati on of the modified instrument to samples containing amines and propoxy lated alcohols.