CONVERSION OF THE FINNIGAN-MAT TSQ-70 THERMOSPRAY IONIZATION INTERFACE TO AN ELECTROSPRAY-IONIZATION INTERFACE

The conversion of a thermospray ionization (TSI) feature of a Finnigan -MAT TSQ-70 mass spectrometer to electrospray ionization (ESI) and its performance are described. The existing source, pumping capacity, fla nges, and temperature controller of the TSQ-70 TS feature were used wi th a few modifications. Conversion of the commercial TS option to a si mple and economically viable ES option has made the analysis of large biomolecules possible without expensive upgrades. To preserve the simp licity of the conversion, desolvation is effected by a heated-capillar y tube (HCT). The HCT and its housing are inserted inside the TSQ-70 T S flange like a solid probe. Mass spectrometric results of low and hig h molecular weight biomolecules, the mass accuracy, sensitivity, and c harge states of the observed ions are comparable to published results by other laboratories. Adequate spectral quality was obtained at short scan times, a required characteristic for interfacing ESI with separa tion methods such as capillary zone electrophoresis.