Simultaneous Determination of Residues of Dipyrone and Its Major Metabolites in Milk, Bovine Muscle, and Porcine Muscle by Liquid Chromatography/Mass Spectrometry

Abstract

A new liquid chromatography/mass spectrometry (LC/MS) method for the determination of dipyrone (DIP) and the DIP-related residues 4-formylaminoantipyrine (FAA), 4-aminoantipyrine (AA), and 4-methylaminoantipyrine (MAA) in milk, bovine muscle, and porcine muscle is presented. The analytes are extracted from the sample with methanol and defatted with hexane. The methanol extracts are then concentrated and injected into the LC system. Compounds are determined by reversed-phase LC using an Inertsil ODS-3 column with ammonium formate-acetonitrile mobile phase and MS detection using positive-ion electrospray ionization. Calibration curves were linear between 0.02 and 0.20 microg/g matrix equivalent concentration for FAA, AA, and MAA, and between 0.2 and 2.0 microg/g for DIP. The relative standard deviations for measurements by the proposed method were <11% for milk and porcine samples, with slightly greater variability for bovine samples. Average recoveries ranged from 82 to 128%, depending on the compound and matrix involved. The method detection limits of FAA, AA, and MAA were <0.02 microg/g for all matrixes tested, while those of DIP were <0.13 microg/g. The proposed method is rapid, simple, and specific, allowing a single analyst to easily prepare over 20 samples in a regular working day.