| The multiresidue analysis of pesticides in herb was studied in this paper,the pesticides studied were detected by GC-ECD/FPD,and the factors were appraised by orthogonal design,the optimized analysis method was obtained and the applicability of method was also studied in other herbs.The main conclusions as following:1.Study on the 20 pesticides multiresidue analysis in herb1.1 The optimization of clean-upThe efficiency of clean-up and the recovery of 20 pesticides was as guideline,the factors were appraised by orthogonal design,such as the kinds of stuffing,the dosage of stuffing and the eluting solvent,the result of delta analysis and recoveries of polar considered,the best efficiency is achieved by collection with silica gel(7.5g) and elution with petroleum ester/acetone(4/6,v/v).The clean-up method was validated by the recovery of three levels(high,middle,low),the recovery ranged from 81.71%～111.65%,the RSDs were lower than 20%.The clean-up method was accorded with the regulation of pesticide residue.1.2 The volume of eluting solventOn the basis of optimized clean-up method,the effect of the volume of eluting solvent to the recovery was investigated.The results showed the volume of eluting solvent was 20 mL.1.3 The optimization of extractionThe factors,such as the solvent,the volume of solvent,the extraction time and the time of extract,were studied by orthogonal design.The data were analyzed by range analysis. The results showed the optimized extract method was following:the extract solvent was acetone / dichloromethane(2:1,v/v),the volume of extract solvent was 40 mL,the extraction time was twice,and the time of extract was 15 min(8min,7min).The optimized method was tested by the recovery of three levels,the range of recoveries was 70.59～115.14%,RSDs was lower than 15%,the optimized extract method meets the analysis of pesticide residue.1.4 The optimized method of disposal of herbBy the orthogonal design and the eluting curve,the optimized method of disposal of 20 pesticides multiresidue in herb was come into being.Five gram of such powder was weighed into beaker and 40mL acetone/dichloromethane(2/1,v/v) was added.It was proceeded ultrasonic extraction for 15 min(8min and 7 min,respectively).Then the extract was filtered and concentrated to 1 mL with a vacuum rotary evaporator equipped with a water bath at 35℃,and the concentrated extract was transfen-ed to a silica gel(7.5g ) column(25cm×1.5cm id) that was prewashed with petroleum ester.The column was eluted by a mixture(40 + 60,v/v) of petroleum ester / acetate(20 mL).The combined eluate was concentrated to near dryness under reduced pressure below 40℃.The residue was reconstituted in 5ml of petroleum ester for final analysis.1.5 The applicability of methodOn the basis of disposal method,five kinds of herb,those was Isatis indigotica Fort, Pltycodon grandiflorum,Cotex mouta,Chrysanthaemum morifolium.and Poria cocos, were choose to appraise the applicability of the optimized method.The results showed that the recoveries were72.51%～113.47%(60.25%for dimethoate) in Poria cocos,Isatis indigotica Fort,Pltycodon grandiflorum,Cotex mouta and respectively,the RSDs were lower than 20%.The results indicated that the optimized method was applicative. Unluckily,the optimized method didn't resolve the recovery in Chrysanthaemum morifolium.1.6 The detect of real sampleA series of commercially available samples of Isatis indigotica Fort,Pltycodon grandiflorum,Cotex mouta and Poria cocos were analyzed,herbal were found to contain pesticide residues,the range of pesticides residue was 0.7～342.4μg/kg,but the level of pesticide residue was lower than the criterion,which explained that the method may used to detect the level of pesticides residue in herb sell in market.1.7 Study on the method of MSPDOn the basis of study above,the analysis method of MSPD was studied.The method was following:the weight of sample was 0.5g,2.0g silica gel was added,then the sample and silica gel were rub adequately,the mixture were eluted by a mixture(40 + 60,v/v) of petroleum ester / acetate(4:6,v/v,15 mL) in glass column.The results showed that recoveries of MSPD method at spiked high concentrations were superior to that at spiked low levels,and under low fortified levels,the recoveries of nearly half of pesticides weren't accorded with demands of pesticide residue analysis.Compared with the method that was developed in the paper,the reproduction of MSPD method was bad,though RSDs of almost all pesticides were lower to 20%(dimethoate was 21.42%).2.Study on pesticide multresidue of 14 organophosphorus pesticides in herbThe optimized method of 20 pesticides multiresidue in herbs that was studied with orthogonal design was to research 14 organophosphorus pesticides residue analysis in Raidix paeoniae Alba by fortifying different concentrations,the mean recoveries of 14 organophosphorus pesticides were 75.68%(diazinon)～93.31%(phorate),except ditalimfos was 70.18%and isofenphos-methy was 72.46%.RSDs were all lower to 16%.
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