Determination of Dufulin Residue in Vegetables, Rice, and Tobacco Using Liquid Chromatography with Tandem Mass Spectrometry

A rapid and accurate LC/MS/MS method using positive electrospray ionization was established for the determination of residues of the novel plant antiviral agent dufulin in samples of tobacco leaf (dry), tomato, cucumber, and rice. Samples were extracted with acetonitrile; cleaned up by dispersive SPE using primary secondary amine, C-18, and graphitized carbon black sorbents; separated on a C-18 column; and confirmed by multiple reaction monitoring mode MS with a matrix effect of -21.5-19.6%. The method showed satisfactory linearity (R-2 >= 0.9912) for the target compound. The LOD and the LOQ were 0.05 and 0.15 mu g/kg, respectively. The mean recoveries from four matrixes varied from 71.9 to 93.6% with intraday RSD in the range of 2.9 to 9.0% and interday RSD 6.9 to 15.2%. The method was successfully applied for analysis of dufulin in actual trial samples.