Background: The high resolving and accuracy power of the HRMS instrument enabled us to
identify the product ions and to propose detailed fragmentation pathways and diagnostic fragment ions.
Methods: In the present work, the fragmentation pathways of five sulfonamides antibiotics, namely
sulfamerazine, sulfathiazole, sulfadiazine, sulfadimethoxine and sulfamethoxazole, by High-Resolution
Mass Spectrometry (HRMS) are presented. The HRMS spectra were recorded with a Q-TOF (Time of
Flight) spectrometer with Electrospray Ionization (ESI) in both negative and positive mode.
Results: Specific characteristic ions for each one of the sulfonamide antibiotics under positive ESI
mode are proposed for the first time. Fragment ions of this particular class of analytes may be used to
rapidly identify compounds with common structural features.
Conclusion: The direct infusion of plasma samples, avoiding any prior chromatographic steps, to identify
the existence of sulfonamide antibiotics is demonstrated herein.