Abstract
An interface for combining a liquid ionization mass spectrometer with a liquid chromatograph (LC) was developed. In this interface, the effluent from a micro-HPLC is deposited on a needle filament in the liquid ionization ion source periodically at a constant rate. Experimental conditions, such as needle filament temperature, cycles of periodic deposition and flow rate, and composition of mobile phase, were investigated to obtain as many solute ions as possible at each cycle. Solute ions produced on the filament were introduced into a quadrupole mass spectrometer through a pinhole and mass spectra were measured continuously. Since one chromatographic peak was divided by the deposition cycle, a group of peaks appeared; the envelope of the peak groups looked similar to the corresponding peak measured by a UV detector. As an example, a sample containing three steroid hormones was measured. A satisfactory RIC (re-constructed ion current) chromatogram and mass spectrum of each component were obtained. The results indicate the usefulness of this interface in which the filament temperature is increased rapidly enough for detecting several solutes at each cycle.
