Galaon, TomaTomaGalaonVacaresteanu, CatalinaCatalinaVacaresteanuAnghel, Dan-FlorinDan-FlorinAnghelDavid, VictorVictorDavid2017-04-062017-04-0620131942-7611http://hdl.handle.net/123456789/784Drug Testing and Analysis Volume 6Nine important 1,4-benzodiazepines and zolpidem were characterized by liquid chromatography-mass spectrometry using a multimode ionization source able to generate ions using both electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), and a single quadrupole mass analyzer. An optimum chromatographic separation was applied for all target compounds in less than 8 minutes using a Zorbax Eclipse Plus column (100 x 4.6 mm, 3.5 μm) kept at 35°C and a 0.3% HCOOH/ ACN/IPA (61:34:5) mobile phase pumped at 1 ml/min. Optimization of LC-MS method generated low limit of quantitation (LOQ) values situated in the range 0.3–20.5 ng/ml. Comparison between differences in method sensitivity, under specified chromatographic conditions, when using ESI-only, APCI-only, and simultaneous ESI-APCI ionization with such a multimode source was discussed. Mixed ESI-APCI(+) mode proved to be the most sensitive ionization generating an average 35% detector response increase compared to ESI-only ionization and 350% detector response increase with respect to APCI-only ionization. Characterization of the nine benzodiazepines and zolpidem concerning their MS fragmentation pathway following ‘in-source’ collision-induced dissociation is discussed in detail and some general trends regarding these fragmentations are set.en-USBenzodiazepinesLC-MSFragmentation pathwayIn-source CIDSimultaneous dual ESI-APCI ionizationArticle