Study of the Fragmentation Pathways of Sulfonamides by High-resolution Mass Spectrometry: Application to their Detection in Plasma by Direct Infusion

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.