| Rape was suffered the sclerotinia sclerotiorum during the whole growth period. Carbendazim and triadimefon are usually used to control the sclerotinia sclerotiorum in the rape flowering. In this work, the spraying amount of pesticides were standard dosage, threefold and fivefold higher dosage. The obtained rapeseed was repackaged for processing and storage experiment. The transformation of carbendazim, triadimefon and its metabolite, triadimenol, from rapeseed to oil during homing processing with hot press and cold press was investigated. The pesticide residues in rapeseed, rapeseed oil and oil cake were determined, to get the processing factor. The effect of storage temperature on the removal of carbendazim and triadimenol was investigate. The main study results are presented as follow:1. The QuEChERS method coupled to high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) was used to determination carbendazim, triadimefon and triadimenol in the rapeseed and oil cake. Analytical performance was carried out. The correlation coefficient of carbendazim, triadimefon and triadimenol were 0.9993-0.9996(1-500μg-L-1), the recovery was 79.0%-98.8% (when the spiked concentration were 0.05 mg-kg-1,0.1 mg-kg-1,0.5 mg-kg-1), and the relative standard deviations(RSDs) were 0.79%-5.84%, the limits of quantification (LOQs) were 0.0004 mg-kg-1,0.0021 mg-kg-1 and 0.0004 mg-kg-1, respectively. These results demonstrated that the proposed can satisfy the analysis of carbendazim, triadimefon and triadimenol residues in rapeseed.2. Gel Permeation Chromatography (GPC) was used to purify triadimefon and triadimenol in rapeseed oil. Using the cyclohexane-ethyl acetate (1:1, V/V) as mobile phase, the fractions were collected separately. The best elution time was 16-23 min with triadimefon and triadimenol in rapeseed oil. The pesticides were determined by HPLC-MS/MS. The correlation coefficient of triadimefon and triadimenol were 0.9993-0.9996 (5-500ug-L-1). the recovery was 91.9%-97.9%(when the spiked concentration were 0.01 mg-kg-1,0.2 mg-kg-1,0.5 mg-kg-1), and the RSDs were 0.79%-5.84%, the LOQs were 0.005 mg-kg-1 and 0.001 mg-kg-1, respectively. These results demonstrated that the proposed can satisfy the analysis of triadimefon and triadimenol residues in rapeseed.3. Determination of carbendazim in the rapeseed oil was established. LC-NH2SPE catridge is used for preconcentration of dichloromethane and methanol (95+5) as elution reagent. The correlation coefficient of carbendazim was 0.9996 (1-500μg-L-1), the recovery was 82.5%-98.8%(when the spiked concentration were 0.01 mg-kg-1, 0.2 mg-kg-1,0.5 mg-kg-1), and the RSDs were 0.56%-4.35%, the LOQs was 0.0009 mg-kg-1, respectively. These results demonstrated that the proposed can satisfy the analysis of carbendazim residues in rapeseed.4. Rapeseed samples with fivefold higher dosage were obtained, stored at the temperature of 15-20 ℃ and-25 ℃. The samples were analysed at 0 d,7 d,14 d, 21 d,28 d,35 d,42 d,49 d after storage. The results showed that carbendazim and triadimenol residues were decreased while the storage time increased gradually, and degradation speed of rapeseed at 15-20 ℃ room temperature is higher than that store at -25 ℃. After 49 days, the degradation rate of carbendazim was 19.9%at room temperature and 7.4%at frozen storage; the degradation of triadimenol was 24.6%at room temperature and 8.5%at frozen storage. Carbendazim degradation rate is slower than triadimenol at room temperature.5. The residues of carbendazim, triadimenol in home press processing were studied. The results showed that, after cold pressing and hot pressing of rapeseed, the pesticide residues of carbendazim and triadimenol were lower in rapeseed oil and oil cake than in rapeseed. After hot pressing, the residue of carbendazim in oil cake was significantly higher than that in rapeseed oil; after cold pressing, the residue of carbendazim in rapeseed oil was slightly higher than that in oil cake. The standard dosage samples was not detected triadimenol in oil cake, but it was detected in rapeseed oil and oil cake with threefold and fivefold higher dosage samples, and triadimenol residue in rapeseed oil is higher than that in oil cake. The average processing factors of carbendazim was about 0.15 for hot pressing and was 0.49 for cold pressing, which indicated that roasting process can also decrease the carbendazim residues obviously by hot press. The average processing factors of triadimenol was about 0.95 for hot pressing and was 0.88 for cold pressing, which showed that the removal efficiency was not satisfactory during process. |
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