Direct infusion nano-electrospray ionization mass spectrometry for therapeutic drug monitoring of ciprofloxacin and its metabolites in human saliva.

A rapid and sensitive method based on direct infusion-nano-electrospray ionization mass spectrometry (DI-nESI-MS) has been developed for the detection and quantification of ciprofloxacin and its metabolites in human saliva. Saliva samples were collected after the oral administration of 500 mg ciprofloxacin tablets. Internal standard (IS), tamoxifen, was added to the collected samples, and then diluted with the ionization solvent, centrifuged and filtered.