A comparative study on the matrix effect of micro pen electrospray ionization tandem mass spectrometry and liquid chromatography coupled with electrospray ionization tandem mass spectrometry

Electrospray ionization (ESI) is easy to be affected by the biological matrix interferences, and thus the accuracy, precision, and reproducibility of the quantitation are significantly impaired. Probe electrospray ionization (PESI) is one of the most typical ambient ionization, which can ionize molecules without complicated sample preparation at the atmospheric environment, and is superior in simplicity, high efficiency, and high throughput. The micro pen electrospray ionization tandem mass spectrometry (μPen-ESI-MS/MS) method was newly developed based on PESI. In this study, the matrix effect of the μPen-ESI-MS/MS method for drug quantitation in plasma samples was evaluated and compared with the liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method. The μPen-ESI-MS/MS and LC-ESI-MS/MS methods for quantitation of five drugs in rat plasma were established respectively, and the matrix factors (MFs) and internal standard normalised matrix factors (IS normalised MFs) were measured. The results showed that the ion suppression of the μPen-ESI-MS/MS method for tacrolimus, flunarizine, and desloratadine was equal to or less than that of the LC-ESI-MS/MS method; the RSDs of the IS normalised MFs of all five drugs were less than 15%, which met the related requirements of the Pharmacopoeia of the People's Republic of China. Therefore, this study investigated the matrix effect of the μPen-ESI-MS/MS method for quantitative analysis of target drugs in plasma samples and provided new data for the application of μPen-ESI-MS/MS in bioanalysis.