Study On Analysis Methods Of Pesticides Residues In Fruits

The achievements of the study were as follows:(1) An analytical method was developed on the simultaneous determination of captan and folpet in fruits by SPE-GC-ECD. The sample was extracted with acetonitrile, cleaned by SPE with silica magnesium sorbent+silica gel, with hexane-dichloromethane-acetonitrile (50+49+1) as eluent. The influencing factors including eluting solvent and its volume, SPE column, pH, volume of water added and stability of the sorbent were discussed. In the concentration range from 0.05mg/L to 2.00mg/L, captan and folpet both had good linearity. Recoveries from spiked samples ranged from 81.5% to 116% and RSDs were not higher than 8.0%.(2) An analytical method was developed on the determination of captan and folpet in apples by SPE-HPLC-UV. The steps for pesticides residues extraction and purification were similar with that in Chapterâ…¡. The mobile phase is a mixture of methanol, acetonitrile and water (0.1mmol/L buffer of acetic acid - ammonium acetate)(50+5+45) at the flow rate of 1.0mL/min. The separation was carried out using an Eclipse XDB-C18 column and UV was set at 210nm. In the concentration range from 10.00mg/L to 200.00mg /L, captan and folpet both had good linearity. Recoveries from spiked samples ranged from 63.9% to 111% and relative standard deviations were not higher than 4.8%. Limits of detection were 0.68mg/kg and 0.50mg/kg for captan and folpet, respectively. The method is precise and accurate for high concentration of captan and folpet, it is suitable for determining of high concentration of captan and folpet in apples. The method of high performance liquid chromatography was compared with gas chromatography through accuracy, precision and sensitivity. It showed that gas chromatography was more accurate, precise and sensitive than high performance liquid chromatography.(3) An analytical method was developed on the determination of kresoxim-methyl, tebuconazole and difenoconazole in apples by SPE-GC-ECD. The sample was extracted with acetonitrile, cleaned by solid phase extraction with NH2, eluted with acetone-hexane (50+50). The influencing factors including eluting solvent and its volume, SPE column and volume of water added were discussed. In the concentration range we determined, kresoxim-methyl, tebuconazole and difenoconazole all had good linearity. Recoveries from spiked samples ranged from 81.6% to 115%; and RSDs were not higher than 10%.The method for simutaneous determination of captan and folpet in fruits, it can determine captan and folpet at the same time, and it was simple, accurate, cheap, so it was suitable for our country. The method for simutaneous determination of kresoxim-methyl, tebuconazole and difenoconazole in apples, it was simple, accurate; and in the case of there were no standard methods for kresoxim-methyl, tebuconazole and difenoconazole in China, it provided reference method for the determination of them in apples.