Analysis of tryptic digests using microbore HPLC with an ion trap storage/reflectron time-of-flight detector.

An electrospray ionization source interfaced to an ion trap storage/reflectron time-of-flight mass spectrometer is evaluated as a rapid, sensitive detector for microbore HPLC. Using the total ion storage capabilities of the trap over a broad mass range, total ion chromatograms of tryptic digests of bovine cytochrome c and bovine beta-casein are obtained following microbore HPLC separations with samples in the low picomole range. The digests are analyzed with the aid of software developed in our laboratory, which can display the selected ion chromatogram (SIC) for each chromatographic peak. The SIC mode can be used for enhancement of the S/N and for identification of a chromatographic peak with a particular mass. In addition, the mass spectrum corresponding to each chromatographic peak can be displayed to check for unresolved chromatographic components.