Simultaneous determination of metronidazole, chloramphenicol and 10 sulfonamide residues in honey by LC-MS/MS

A liquid chromatography-tandem mass spectrometric method was established for the simultaneous determination of residues of metronidazole, chloramphenicol and 10 sulfonamides (sulfadiazine, sulfathiazol, sulfapyridin, sulfamerazin, sulfameter, sulfamethazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfamethoxazole and sulfadimethoxin) in honey samples. Samples were first dissolved in water. Sonication was carried out in an ultrasonic bath to extract the target analytes with acetonitrile and the extract was concentrated by rotary evaporation. Chromatographic separation was carried out on an MGIII-C-18 column (2.1 mm x 150 mm, 5 mu m) using a mobile phase made up of methanol and 50 mmol L-1 ammonium acetate aqueous solution (include 0.3% formic acid) and gradient elution. Metronidazole, chloramphenicol and the sulfonamides were monitored in negative ion or positive ion selected reaction monitoring modes and quantified by the external standard method. The limit of detection was 0.1 mu g kg(-1) for chloramphenicol and 1.0 mu g kg(-1) for metronidazole and each sulfonamide, respectively. The linear range for chloramphenicol was 0.1-25.0 mu g kg(-1), and for both metronidazole and the sulfonamides were 1.0-100.0 mu g kg(-1), and all the correlation coefficients were greater than 0.99. The average spike recoveries of the method ranged from 81.6% to 99.7% with relative standard deviations of 3.61-8.97%. Therefore this method is convenient, rapid, sensitive and reliable, and can be successfully applied for the simultaneous detection of metronidazole, chloramphenicol and 10 sulfonamide residues in commercial products.