Evaluation on a Simultaneous Analytical Method of Pesticide Residues in Limes

A LC-MS/MS simultaneous analytical method for screening 191 pesticide residues in limes had been developed and validated. Pesticides were extracted with acetonitrile from samples. Then mixed salts, which were anhydrous magnesium sulfate for dehydration, sodium carbonate for adjusting pH, and sodium chloride for salting out, were added to the sample. After centrifugation, supernatant was transferred to a tube. The sample solution was cleaned up using solid phase extraction (SPE) with C18/GC/PSA for the determination by LC-MS/MS. The developed method was improved the recovery rate of thiabendazole, which had a low recovery rate by the conventional method. Validation study, which was following the guidelines of the Ministry of Health, Labor and Welfare, were carried out at 0.01 and 0.1 μg g-1 to evaluate the method. The results of 175 pesticides out of 191 were with satisfactory. A total of 19 imported lime samples sold in Tokyo was analyzed to evaluate the method, then 18 samples contained pesticide residues below MRLs. The developed method is applicable for detection of pesticide residues in lime.