Determination Of Tebufenozide And Methoxyfenozide Residues In Vegetables Using Liquid Chromatography Electrospray Tandem Mass Spectrometry

An analytical method was developed for the determination of tebufenozide and methoxyfenozide residues in vegetables. The tebufenozide and methoxyfenozide were extracted from the matrices by alkali acetonitrile, and purified by solid-phase extraction. The tebufenozide and methoxyfenozide residues were subsequently analyzed by the reversed phase HPLC with electrospray mass spectrometric detection. Mass spectral acquisition was realized by select reaction monitoring of two diagnostic transition reactions. The qualitative results were obtained based on retention time, the precursor ion and two daughter ions, and the quantitation results were on the intension of the characteristic m/z 297 ion and m/z 149 ion. The linear range is 5.0 - 200 mu g/L and the correlation coefficients (r(2)) were more than 0.996. The average recoveries ranged from 90% to 110% for tebufenozide and 70% to 80% for methoxyfnozide in replicate sets of vegetable samples fortified with standard concentration of 4.0, 10.0 and 20 mu g/kg, and the relative standard deviation (RSD%) were less than 8%. The detection and quantitaion limit were 1.0 mu g/kg and 4.0 mu g/kg, respectively. The method is simple and suitable for the routine and confirmation analysis.