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 procedure involves the extraction of tebufenozide and methoxyfenozide using alkali acetonitrile before solid-phase purification from the matrices. The tebufenozide and methoxyfenozide residues were subsequently determined by an electrospray mass spectrometer after separated by the reversed-HPLC. Mass Spectrum acquisition applied Selected Reaction Monitoring (SRM) to diagnostic transition reactions. The qualitative results were obtained based on the retention time, the precursor ion and two daughter ions, and the quantitative results were based on the intension of the characteristic m/z 297 ion and m/z 149 ion. The linear range was from 5.0–200 ng ml−1 and the correlation coefficients (r) were higher than 0.996. The average recovery ranges from 90% to 110% for tebufenozide and 70% to 80% for methoxyfenozide in the replicate sets of vegetable samples fortified with drug concentration of 4.0, 10.0 and 20 μg kg−1, and the relative standard deviations (RSD) were less than 8%. The detection limit and the quantification limit of the method were 1.0 and 4.0 μg kg−1, respectively. This method is quite suitable for determining the residues of tebufenozide and methoxyfenozide in vegetables.