title: High-performance liquid chromatography-thermospray mass spectrometry of ten sulfonamide antibiotics. Analysis in milk at the ppb level.
abstract: Ten sulfonamide antibiotics including sulfanilamide (SNL), sulfamethazine (SMZ), sulfamethizole (SMTZ), sulfachloropyridazine and sulfaquinoxaline (SQX), were analyzed by thermospray (TSP) mass spectrometry on-line with a high-performance liquid chromatography-UV detection system. Except for the pairs SMZ-SMTZ and sulfadimethoxine-SQX, the standards were resolved in both the UV and TSP profiles. Co-eluting compounds could be differentiated in TSP by their different relative molecular masses. The [M+H]+ ion was the base peak for all the standards except SNL, which showed an [M+NH4]+ ion. Collision-induced dissociation of the [M+H]+ ions afforded daughter ion spectra characterized by common ions at m/z 92, 108 and 156, and ions derived from the amine substituent ([MH-155]+). TSP detection limits [signal-to-noise ratio (S/N) > 3] were below 20 ng (scan mode), 2 ng (selected reaction monitoring, daughter ions from [M+H]+) and 400 pg (selected ion monitoring). UV detection limits were ca. 2 ng (S/N > 5). Results obtained from the multi-residue analysis of spiked cow milk samples at the low ng/ml level are presented.
authors.affiliation: US Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079.
authors.forename: J
authors.initials: J
authors.lastname: Abián
authors.forename: M I
authors.initials: MI
authors.lastname: Churchwell
authors.forename: W A
authors.initials: WA
authors.lastname: Korfmacher
mesh_terms: D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D008892:Milk / Q000737:chemistry*; D013449:Sulfonamides / Q000032:analysis*
chemical_list: D013449:Sulfonamides