Determination of Metabolites of Nitrofuran in Sausage by Hyphenation of High Performance Liquid Chromatography and Mass Spectrometry in Tandem

High performance liquid chromatography in hyphenation with tandem mass spectrometry (LC-MS/MS) was applied to the determination of matabolites of nitrofuransin ausage.Protein combined metabolites in the sample were hydrolyzed and derivatized with 2-nitrobenzaldehyde overnight at 37 ℃ in dil.HCl solution.Acidity of the solution was adjusted to pH 7.0-7.5,and centrifuged at 3 000 r·min-1 for 10 min.The supernatant layer was separated and extracted with ethyl acetate.Derivatized products of metabolites of nitrofurans were then determined by HPLC-MS/MS under the condition of electrospray ionization in positive mode (ESI+) using multi-ionic reaction monitoring.Method of external standard was used in the determination.Recovery tests were made by addition of standards in the range of 0.5-10 μg·kg-1,and results obtained were ranging from 77.3% to 90.7% with values of RSD′s less than 9%.Detection limits (S/N=3) of the method were found to be 0.10 μg·kg-1 for metabolites of 3-amino-2-oxazolidinone (AOZ),5-methylmorpholino-3-amino-2-oxazolidinone (MAOZ) and semicarbazide (SC),and 0.20 μg·kg-1 for 1-amino-hydantoin (AHD).