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, flanges, and temperature controller of the TSQ-70 TS feature were used with a few modifications. Conversion of the commercial TS option to a simple and economically viable ES option has made the analysis of large biomolecules possible without expensive upgrades. To preserve the simplicity of the conversion, desolvation is effected by a heated-capillary tube (HCT). The HCT and its housing are inserted inside the TSQ-70 TS flange like a solid probe. Mass spectrometric results of low and high molecular weight biomolecules, the mass accuracy, sensitivity, and charge 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 separation methods such as capillary zone electrophoresis.