丙溴磷在棉花上的残留分析研究.doc

本科毕业设计（论文）题目_指导教师_辅导教师_学生姓名_学生学号_院（部）专业班二七年六月八日丙溴磷在棉花上的残留分析研究化工学化学工程与工艺2003级2中文摘要I丙溴磷在棉花上的残留分析研究摘要本文对丙溴磷在棉叶上的降解动态、棉籽和棉叶上的最终残留量进行了研究。另外，还对气质联用法获得的丙溴磷质谱图进行了解析。对棉花上丙溴磷的残留动态和最终残留量分析测定采用的方法是以丙酮为提取溶剂，石油醚-氯化钠水溶液液液分配，乙腈-石油醚反萃取，硅胶吸附净化；用配备电子捕获检测器（63Ni-ECD）的气相色谱仪检测。本检测方法最小检出量为1×10-11g，最低检出浓度为0.02mgkg-1。丙溴磷工作曲线方程为Y=-234213421759X，相关系数r=0.9949。本文方法的添加浓度为0.02mgkg-1、0.2mgkg-1和2mgkg-13个水平。棉籽平均回收率为86%104%，相对标准偏差为5.33%15.86%；棉叶的回收率平均87%104%，相对标准偏差为7.20%14.28%。该数据符合农药残留试验准则的要求。残留动态试验结果表明，在棉花上喷施500gL-1丙溴磷乳油，剂量1875ghm-2，有效成分，其在棉叶上的原始沉积量很高，济南试验点为110mgkg-1，长沙为83mgkg-1，但其降解很快。丙溴磷在棉叶上的降解动态方程济南为：Ct=107e-0.9891t，r=-0.9733，半衰期t1/2为0.7d；长沙为：Ct=54e-0.4805t，r=-0.9660，半衰期t1/2为1.4d。以降解速率评价，丙溴磷属于易降解农药。济南和长沙两地试验点棉籽的残留量最大值为0.13mgkg-1，可以看出，棉籽的残留量远低于推荐的最大残留限量2mgkg-1；济南棉叶的丙溴磷残留量最大值为0.32mgkg-1，长沙的为19mgkg-1。根据残留试验数据和国际食品法典的有关规定，建议在棉花上使用500gL-1丙溴磷乳油防治棉铃虫，施药剂量不要高于有效成分937.5ghm-2，最多施药3次，最后一次施药距采收间隔期不少于21d。综合考虑各种限制因素，棉籽上的丙溴磷最大残留限量（MRL）暂定2mgkg-1较适宜。关键词：GC-ECD；丙溴磷；棉籽；棉叶；农药残留分析ABSTRACTISTUDYONDETERMINATIONOFPROFENOFOSRESIDUEINCOTTONABSTRACTDeterminationofprofenofosresidueincottonwasstudied.Inaddition,itwasalsoparsedthemassspectrogramofprofenofosbyGC-MS.Theanalysissamplewasextractedbyacetone,liquid-liquiddistributionwithpetroleumetherandacetonitrileinoneseparator,thendistributionwithpetroleumetherandwatersolutionofsodiumchlorideinanotherseparator,andcleanedupwithsilicagelcolumn.TheresidualdynamicsandfinalresiduallevelofprofenofosincottonseedsandcottonleavesweredeterminedwithGC-ECD.Themethodforlimitofdetectionwas1×10-11g,andthelimitofquantificationwas0.02mgkg-1.TheworkingcurveofprofenofoswasY=-234213421759X,r=0.9949.Whilefortificationlevelwas0.02mgkg-1,0.2mgkg-1,2mgkg-1,theresultshowedthatthemeanrecoverieswere86%104%andtheRSDwas5.33%15.86%incottonseeds,andthesewere87%104%andtheRSDwas7.20%14.28%incottonleaves,respectively.ThesewereaccordingwithGuidelineonpesticideresiduetrialsinChina.Whenhighdosage（1875ghm-2,a.i.）ofprofenofosemulsionwasappliedinthecottonleavesoncetime,theinitialresidueofprofenofosinitwas110mgkg-1inJinanand83mgkg-1inChangsha.ThedegradationequationofprofenofosincottonleaveswasCt=107e-0.9891t，r=-0.9733inJinan,andCt=54e-0.4805t，r=-0.9660inChangsha,andthehalf-livesofprofenofoswere0.7dand1.4d,respectively.Theresultsshowedthatprofenofosiseasytodegradeincotton.Themaximumvalueofresidueincottonseedswas0.13mgkg-1inJinanandChangsha,whichwasfarlowerthantherecommendedMRL2mgkg-1；theABSTRACTIImaximumvalueofresidueincottonleaveswas0.32mgkg-1inJinanand19mgkg-1inChangsha,respectively.AccordingtothedataofprofenofosresidueandregulationofCODEX,itsuggestedthatthedosageof500gL-1profenofosECshouldbenomorethan937.5ghm-2forapplying3times,andtheintervalfromapplyingtoharvestingwasnolessthan21days.Consideringallkindsoffactors,itisreasonablethattheMRLofprofenofosincottonseedsis2mgkg-1.KEYWORDS:GC-ECD；profenofos；cottonseeds；cottonleaves；pesticideresidueanalysis