An efficient liquid chromatography - Mass spectrometry interface for the generation of electron ionization spectra

The use of a new LC-MS interface (cap-EI), part of a Waters Integrity syste m, capable of generating EI spectra at micro dow rates is presented. The ca p-M interface relies on the production of a fine aerosol by means of a nebu lizer and supported by a nitrogen jet. Sensitivity, response linearity, rep roducibility, and LC compatibility of the interface were thoroughly examine d using testosterone, caffeine, a mixture of antiinflammatory drugs, and 3, 4-dihydroxybenzoic acid as test compounds. The interface is fully compatibl e with LC requirements such as high-water- and/or -buffer-content mobile ph ases. Reproducibility, high sensitivity in scan mode, as well, to produce l ibrary-searchable EI spectra, 2 orders of magnitude linearity, together wit h an intrinsic simplicity of the entire system are the key features of cap- M interface.