Rapid Detection of Powdered Antibiotics by Surface Desorption Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry

A homemade surface desorption atmospheric pressure chemical ionization (SDAPCI) source was coupled to a linear ion trap(LTQ) mass spectrometer for direct detection of various active constituents such as amoxicillin, norfloxacin, cefradine in powdered pharmaceutical preparations. In the SDAPCI source, ambient air (relative humidity 60%) was used as a reagent and a corona discharge was employed to generate primary reagent ions (H3O+, for instance), which were then directed to impact the sample surface for desorption and ionization at atmospheric pressure. Under the optimized experimental conditions, photolysis products of norfloxacin were rapidly detected and identified. The detection limit of 8x10(-13) g/cm(2) was achieved in the tesing of antibiotics. Single sample analysis was completed within 1 min. The results show that multiple stage SDAPCI mass spectrometry is a useful tool for fast detection of active ingredients and trace impurities in powdered medicines, especially when the DAPCI technique is coupled with portable mass spectrometers.