Probe electrospray ionization coupled to a quadrupole time-Of-flight: A feasibility study for the detection of cocaine and its derivatives in oral fluid.

Probe Electrospray Ionization (PESI) is an atmospheric pressure ionization method that can be directly coupled with a mass spectrometer to allow ultrafast analyses without chromatographic separation and with minimal sample preparation. Using the particular case of cocaine and its metabolites in human oral fluid, the main objective of the present study was to test the feasibility of a new hybrid system combining a PESI source and a quadrupole time-of-flight (QTOF). The best results were obtained for a sample preparation with a simple dilution of 100 µL of oral fluids in an ethanol / 10 mM ammonium formate buffer (50/50) and 10 µL deposited on a dedicated sample plate and introduced into the PESI source.