Residual Degradation Dynamics And Residue Of Phoxim In Yali Pear Fruit

Nowadays pesticide is widely used in fruit production. It has polluted our living environment and also the fruit itself at the same time, which endangered the edible safety of the consumers. With the development of people's living level, the voice for "non-public hazards fruit" has become louder and louder, and "Green fruit" became more and more popular. The extra remaining pesticide in fruit limited our export badly and restricted our earning foreign exchange. Therefore, using pesticide reasonably and safely has been the key link in fruit production. The supervision and analysis of pesticide residue in fruit plays an important role in the instruction of the reasonably and safely used pesticide.Yali pear fruit is the main breed of our traditional ones. They are also the important fruits for export in our country. In the production, paying attention to the prevention and cure of sicknesses and insects and using pesticide reasonably and safely play an important role in improving the quality of fruit. Busck is the main insects of pear trees. They spread widely in pear production areas in our country, which affected the quantity and quality of Yali pear fruit. People use phoxim to prevent and treat sicknesses and insects. Therefore, doing the instruction, supervision and management work of using pesticide is meaningful for the production of "non-public hazards fruit".There was few report on the study of residual analysis of phoxim in Yali pear fruit. Hence, phoxim as the study object, were sprayed in order to proceed the study of residual degradation dynamics and final residue. Residue was detected by GC.The main results were as follows:1 Studies on residual degradation dynamics of phoxim in Yali pear fruit were according to spraying once, sampling time after time. The results showed that: Degradation curve equations of phoxim in totle fruit in different term were: C=0.2452e^-0.3407t,00.2417e^-0.3606, C=0.2191e^-0.3526trespectively, and the correlation coefficients were 0. 9563, 0.9585, 0.9565 respectively, and the half lives were: 2.03,1.92,1.91d. Residual degradation dynamics of phoxim in different term in Yali pear fruit were all accorded with C=Coe-kt, and all had high relativity, and in normal conditions, degradations were very fast.2 The final residue of phoxim in the pericarp was 0.228mg/kg, and which in the pulp and in the core were, 0.0164mk/kg and 0.0111mg/kg after sprayed 1 time and that were 0.0347mg/kg, 0.0313mg/kg, 0.0173mg/kg in the the pericarp, in the pulp and in the core after sprayed 3 times. The final residue in different part of Yali pear fruit was influenced bydifferent spraying times of phoxim. But whatever once or three times a year, the final residue in Yali pear fruit was not higher than MRL.3 The final residue of phoxim in the pericarp was obviously higher than that was in the whole fruit, in the pulp and in the core. That was to say: the final residue of phoxim was focused in the pericarp, only a little in the pulp and in the core.4 The final residue of phoxim in the no bagged Yali pear was from 0.0119mg/kg⁰.0347mg/kg. The residue of the bagged was lower than the LOD. The result showed that it can reduce the final residue of phoxim in Yali pear fruit by bagging when fruit growth.