Determination Of An Ultrasound-assisted Solvent Extraction Method And Propamidine Fungicide Residues In Tomato Fruit By Reserve Phase High Pressure Liquid Chromatography

Propamidine is a novel systemic plant fungicide which is mainly used to control variousdiseases caused by botrytis fungi on fruits and vegetables under field and greenhouseconditions. It was reported that propamidine is of low toxicity, safe to human being andenvironment. However, no published data are available concerning the residues ofpropamidine in plant extracts. Therefore, residual analysis study of propamidine in tomatobecomes indispensable to guarantee the use of propamidine in field according to goodagricultural practices.The present study is the first attempt for determination and validation of a method forpropamidine residues in tomato fruits. A method of reverse phase high performance liquidchromatography (RP-HPLC) UV detection using two types (5μm and10μm) of HypersilBDS C18column (4.6mm×250mm) was tested. The extraction of propamidine was basedon ultrasonic assisted solvent extraction using an extracting solvent including pure methanol,methanol acidified with phosphoric acid, and HCl-PBS solution. The determinate method wasvalidated and used for propamidine residues quantification in the residues kinetic dissipationstudy.For method determination the best analytical signals response of propamidine fungicidewas achieved with a mobile phase consisting of0.1%phosphoric acid (H3PO4), methanol/de-ionized water (V/V=80:20) solution containing3.0mmol/L SDS. Propamidine was extractfrom tomato fortified and real samples using an ultrasound-assisted solvent extraction. Thesamples were analyzed using reverse phase high performance liquid chromatography with10μm Hypersil BDS C18column (4.6mm×250mm) at the flow rate of1.0ml/min and thecolumn temperature of25oC; injection volume was20μl and the UV detector wavelength wasset at262nm using an isocratic elution system. The method was validated with good linearityin the concentration range of50–600mg/L with determination coefficient>0.999.Satisfactory recoveries ranged from87.97to106.34%with relative standard deviations between0.169and3.503%were obtained for fortified samples. The detection limit andquantification limit were0.07mg/Kg and0.2mg/Kg respectively.For the dissipation study the experimental trials were conducted in a glasshouse atResearch&Development Center of Biorational pesticide (RDCBP), Northwest A&FUniversity, China and in solar greenhouse condition at the village of Xiao-zai (Shaanxi, China)located at fifteen kilometer in the west of Northwest A&F University. The initial depositranged from4.69to2.87mg/Kg and5.70to2.45mg/Kg for all treatments respectively in thetrial of glasshouse and greenhouse. The dissipation of propamidine was found to be first-orderkinetics dissipation, independent of the initial deposit, application dose and the number ofapplication in both environments (glasshouse and greenhouse). The corresponding half-liveranged from5.331to7.875days in glasshouse trial and4.880to6.300days in greenhouse.These propamidine residues dissipated below the limit of detection of0.07mg/Kg28daysafter the last treatment in both cases. The results found were acceptable and confirmed thatthe method is suitable for propamidine residues quantification. The residues data from realsamples carried out in glasshouse and greenhouse tomato had proved that the method could beuseful for the establishment of MRL of propamidine and routine residues analysis.Compared to other method used in pesticide determination, the Ultrasound-AssistedSolvent Extraction Method using Reserve Phase High Pressure Liquid Chromatographydeterminate and validated in this work is easy, quick, efficient and no expansive.