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 chromatography-mass spectrometry (LC-TSP-MS), using a resin-based stationary phase, is described. The use of such a stationary phase eliminates the need of using an ion-pairing agent, which often is incompatible with mass spectrometric detection. Gradient elution has been used to improve the separation and to reduce the analysis time. Detection limits in selective ion monitoring mode as well as in selective reaction monitoring, are in the order of 50 pg for each compound. The usefulness of the method has been demonstrated with the bioanalysis of antrenyl in plasma, using mepenzolate as an internal standard, showing a limit of determination of 1 ng ml(-1).