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[Determination of five imidazole pesticide residues in fruits by Turbo flow online purification-ultra performance liquid chromatography-tandem mass spectrometry].

A Turbo flow-ultra performance liquid chromatography-tandem mass spectrometry (TF-UPLC-MS/MS) method was developed for the determination of five imidazole pesticides (imazapyr, triazoxide, rabenzazole, prochloraz and fenamidone) in fruits. The fruit samples were dissolved in saturated sodium chloride solution and extracted by acetonitrile. After the acetonitrile layer was evaporated and redissolved with acetonitrile-water (1 :1, v/v), the fruit samples were analyzed by TF-UPLC-MS/MS. The main factors influencing the purification efficiency including the TF column, mobile phase, elution solution and elution rate were optimized. Under the optimized experimental conditions, the analytes were purified by Turbo flow C18 column (50 mm x 1.0 mm) and separated on a Hypersil GOLD aQ column (100 mm x 2.1 mm) using the mobile phases of acetonitrile and 5 mmol/L ammonium acetate (containing 0.1% (v/v) formic acid) aqueous solution with gradient elution. The compounds were detected by selective reaction monitoring (SRM) via positive electrospray ionization (ESI(+)). The linear range of the method ranged from 0.007 5 to 0.75 mg/L for all the five imidazole pesticides, with the correlation coefficients (r2) greater than 0.99. The limits of quantification were 0.005 mg/kg for all the five imidazole pesticides. The recoveries were in the range from 71.2% to 122.4% at the spiked levels of 0.005, 0.01, 0.05 and 0.5 mg/kg with the relative standard deviations ranging from 0.5% to 8.9% in actual samples. The results indicate that the developed method is simple, efficient and precise, and can be a reliable technique for the determination of the five imidazole pesticides in fruit samples.