Rapid analysis of aerosol drugs using nano extractive electrospray ionization tandem mass spectrometry

Aerosol drugs dominate a significant share of pharmaceutical preparations on the market. A novel sensitive method utilizing nano extractive electrospray ionization mass spectrometry (nanoEESI-MS) has been developed for the rapid analysis of aerosol drug samples with quantitative information. Without any sample pretreatment, aerosol drugs were manually sprayed into the primary ion plume created by a nano electrospray emitter for direct ionization under ambient conditions. The analyte ions of interest were guided into an ion trap mass spectrometer for tandem mass analysis. The active ingredients of various aerosol drugs, such as econazole nitrate, beclomethasone dipropionate, binary mixture of methyl salicylate and diphenhydramine, terbutaline, and salbutamol, were rapidly detected using nanoEESI-MS. A single sample analysis could be completed within 1.2 s. Tandem mass spectrometry was used to confirm the identification of important compounds in each aerosol drug sample. Reasonable relative standard deviation (RSD = 6.39%, n = 13) and acceptable sensitivity (10 ppt, 100 μL) were found for the salbutamol aerosol sample, which suggests that nanoEESI-MS has the quantitative capacity for analyzing complex pharmaceutical samples. This method was further extended to study the thermal decomposition process of salbutamol, showing that the degradation kinetics of salbutamol can be conveniently tracked. Our data demonstrate that nanoEESI tandem mass spectrometry is a fast and sensitive technique for the analysis of aerosol drug preparations, showing promising applications in pharmacology studies and in situ analysis of aerosol drugs on the market.