Study On The Residual Behaviour Of Tebuconazoln And Propineb In Apple

In order to provide residual behaviour of 65% Tebuconazole·Propineb WG,analysismethods of tebuconazoln and propineb residue and degradation in apple and soil and its finalresidues were studied and the effect of related factors of pesticide residue. The results wereshown as follows:1.An analysis and purification method of tebuconazoln residues was established in appleand soil.Tebuconazoln was extracted with acetone and re-extracted by petroleum addedsodium chloride aqueous solution.The concentrated extracts as petroleum for mobile phasewere detected in NPD.The precision,sensitivity and accuracy of this method could be up tothe standard of pesticide residue determination.2. An analysis method of propineb residues was established in apple and soil.Propinebcould be decomposed in a heated closed reaction chamber under acid condition.The productcarbon disulfide was detected by headspace sampling method,then the residual volume ofpropineb was obtained through conversion.An analysis method of ethylenethiourea residueswas established in apple and soil.Ethylenethiourea was extracted with methanol andpurification purified by petroleum.The concentrated extracts as methanol for mobile phasewere detected with HPLC-UV.The precision,sensitivity and accuracy of this method could beup to the standard of pesticide residue determination.4.Degradation dynamic of 65% Tebuconazole·Propineb WG in apple was studied byfield experiments in Tianjin,Shandong and Shanxi province for two years. The apple wastreated with pesticide of recommended dose of 1.5 times.The result showed that thedegradation procedure was up to the mathematic pattern:C=C0e-kt.This pesticide was degradedeasily.5.With sprayed 65% Tebuconazole·Propineb WG on apple three or four times atrecommended dosage or 1.5 times of it, at the interval of 10d.Before the last application fordetecting,the result of the maximum residue of tebuconazol and propineb were 0.1314mg/kgand 1.9113mg/kg.The MRLs of tebuconazol in apple was 0.2mg/kg according to the pesticideresidue standards of japanese positive list system.The MRLs of propine in apple was 2mg/kgaccording to the pesticide residue standards of Ministry of Agriculture ofChina(GB2763-2005).It is safe that the residue of tebuconazol and propineb used in apple onthe 28th day after applying 1.5 times of the recommendation dosage at 3-4 times at interval of10 days.6.Pesticide residues were influenced by the climate of three province for 2 years(wind,temperature, rainfall, sunshine etc),soil conditions (moisture content, microorganisms andenzymes etc)and pesticide application status(dosage and times).