Determination of Sulfamethoxazole and Trimethoprim and Their Metabolites in Hospital Effluent

In this work, an analytical methodological study was carried out to determine the antimicrobials sulfamethoxazole and trimethoprim, as well as their metabolites, in hospital effluent. The determinations were conducted by liquid chromatography tandem mass spectrometry using a hybrid triple quadrupole‐linear ion trap mass spectrometer (LC‐QqLIT‐MS). The data acquisition was made in selected reaction monitoring (SRM) mode, in which two SRM transitions were monitored to ensure that the target compounds were accurately identified by the information dependent acquisition (IDA) function. The limits of detection (LOD) and quantification (LOQ) were 0.25 and 0.80 µg L−1 for sulfamethoxazole and 0.15 and 0.50 µg L−1 for trimethoprim. The linear range for the SMX was 0.8–100.0 µg L−1 and TMP was 0.5–100.0 µg L−1 on the basis of six‐point calibration curves generated by means of linear regression analysis. The coefficients of the correlation were higher than 0.999, which ensured the linearity of the method. The average concentration of sulfamethoxazole and trimethoprim found in hospital effluent was 27.8 and 6.65 µg L−1, respectively. The analytical methodology employed allowed two metabolites to be identified, N4‐acetyl‐sulfamethoxazole and α‐hydroxy‐trimethoprim. Fragmentation pathways were proposed. An analytical methodological study was carried out to determine the antimicrobials sulfamethoxazole and trimethoprim, as well as their metabolites, in hospital effluent. Two SRM transitions were monitored to ensure that the target compounds were accurately identified by the IDA function.