Study On The LC-MS/MS Methods For Detecting Benzmidazole Fungicides And Metabolites In Concentrated Fruit Juice

Benzimidazole fungicides as fungicides are widely applied to crops and agricultural products. But studies have showed that benzimidazole fungicides seriously endanger the food security. At present the technology level for detecting the benzimidazole fungicides residuals in concentrate fruit juice of our country is backward, few reports about the residual detection of Benzimidazole fungicides were reported by the mass media and no national standards for the benzimidazole fungicides residue testing in concentrate fruit juice has been established in our country. As for these reasons, it’s significantly important to carry out benzimidazole fungicides and the metabolites residue research in concentrated fruit juice and established the LC-MS/MS analysis method for inproving the detection technology, breaking international trade barriers, and for ensuring the quality and safety of our concoutry’s import and export of concentrated fruit juice.In this article, the LC-MS/MS analysis method of detecting Benzimidazole fungicides residues and its metabolites in concentrated fruit juice was studied and established. And the common degradation of benzimidazole and their interactions in concentrated juice was also studied and analysed. The results about the research are as follows:1. The LC-MS/MS analysis method for detecting Benzimidazole fungicides residues and its metabolites in concentrated fruit juice was studied and established. The pretreatment conditions are:for2g sample,20mL acetonitrile as extraction solution, extraction pH is defined as8.5-8.6, extracting for2times, the extraction time is30mins, determine the PSA column for purification column, concentration is1.5mL-2mL; the best chromatographic conditions are:chromatographic column of ZORBAX Eclipse XDB-C18column (Agilent, USA):4.6mm×50mm (diameter), particle size of1.8μm, the mobile phase consisted of buffer salt solution (0.1%-10mmol/L ammonium formate, A) and methanol (B) gradient elution, flow rate was0.4mL/min, the injection volume was10μL, the column temperature was40℃. The method established is sensitive and reliable. When the adding concentration of the5fungicides was1,2,10μg/kg (2-AB,5-hydroxyl thiabendazole were2,4,20μg/kg), recovery rate about70.7%～107.5%and the coefficient of variation in0.1%～11.8%can be obtained. And the detection limits of the news method are:2-aminobenzimidazol (2-AB)2μg/kg,5-hydroxyl thiabendazoleμg/kg, carbendazim, thiabendazole1μg/kg and1μg/kg, Thiophanate-methyl1μg/kg. The separation effect and the linear relationship of the the method established is sensitive and reliable. And this method can be used to detecte and fully reflect the residual level of main benzimidazole fungicide and intermediate transformation products in concentrated fruit juice. The application of this method has the vital significance to the quality and safety control of concentrated fruit juice.2. The standard stability of4kinds of benzimidazole fungicides standard solution in the course of one year was studied. The stability results of the4kinds of benzimidazole fungicides were as follows:in the condition of4℃,4kinds of fungicides degradation capacity is40.63%-86.81%; when mixed storage, degradation speed of2-aminobenzimidazol was slower than separated storage, degradation speed of carbendazim and Thiophanate-methyl was faster than separated storage; while the degradation speed about thiabendazole is not significantly changed; when in the condition of-18℃, the4fungicides were relatively stable, with almost no degradation occurs. The experimental results about the standard stability of benzimidazole fungicides can be as the theoretical basis for comprehensively studying the method for detecting the benzimidazole fungicides residues in concentrated fruit juice, the reference basis for studying the the degradation rule of the4kinds of benzimidazole fungicides in concentrated fruit juice and can also be the reference for using the4kinds of benzimidazole fungicides.3. The LC-MS/MS analysis method for simultaneously detecting of4benzimidazole fungicides and metabolites residues in concentrated fruit juice was carried out by different experiment rooms to prove the validation of the method. In Shaanxi, Shanghai, Shanxi, Fujian, Liuzhou, Dongxing entry-exit inspection and Quarantine Bureau, the method was used to detect the5compounds in the concentrated apple, pear, mango, passion fruit, orange, lychee, pineapple juice blank sample which were added the5compounds standard. The adding concentration of the5compounds mixed standard solution was1,2,10μg/kg respectively (2-AB,5-hydroxyl thiabendazole were2,4,20μg/kg), the laboratory test results show the range of recovery rate is83.5～102.7%, the coefficient of variation was1.2～6.3%. Test results show that the new method is feasible.