ANALYSIS OF QUATERNARY AMMONIUM DRUGS BY THERMOSPRAY LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY USING A RESIN-BASED STATIONARY-PHASE

The analysis of quaternary ammonium drugs by thermospray liquid chroma tography-mass spectrometry (LC-TSP-MS), using a resin-based stationary phase, is described. The use of such a stationary phase eliminates th e need of using an ion-pairing agent, which often is incompatible with mass spectrometric detection. Gradient elution has been used to impro ve the separation and to reduce the analysis time. Detection limits in selective ion monitoring mode as well as in selective reaction monito ring, are in the order of 50 pg for each compound. The usefulness of t he method has been demonstrated with the bioanalysis of antrenyl in pl asma, using mepenzolate as an internal standard, showing a limit of de termination of 1 ng ml(-1).