Analysis Of Pesticide Residues In Chrysanthemum By Supercritical CO₂ Combined With Gas Chromatography-mass Spectrometry

Chrysanthemum is a traditional Chinese herbal medicine,which has both clinical medicinal value and daily nutritional value.The growing consumption of chrysanthemum inevitably leads to the increase of chrysanthemum planting and pesticide use.In order to protect people’s health and food safety,it is very important to develop accurate and rapid methods to detect pesticide residues in chrysanthemum for effective monitoring of product quality and ensuring consumer safety.At present,the extraction and detection methods of pesticide residues in Chinese herbal medicine are mostly solvent extraction,gas phase and liquid phase detection.In this study,the methods of supercritical CO₂ extraction and purification of chlorpyrifos,metalaxyl,Kungfu and fenvalerate pesticides in chrysanthemum were explored,and a method for the determination of pesticide residues by gas chromatography-mass spectrometry was established.The details are as follows:1.The optimum conditions of SFE for chlorpyrifos and Metalaxyl in chrysanthemum were as follows:the pressure was 400 bar,the temperature was 50℃,the volume of CO₂ was 40mL,and the modifier was acetonitrile,the extraction rate was 91.15%and 96.88%respectively;the best SFE conditions of Kungfu were as follows:the pressure was 400 bar,the temperature was 30℃,the volume of CO₂ was 30 mL,the modifier was methanol,the extraction rate was 96.71%;the optimum conditions of fenvalerate SFE were:pressure of400 bar,temperature of 70℃,volume of CO₂ 20 mL,modification of SFE The extraction rate was 95.64%.Taking the extraction rate as the reference index,the better extraction conditions of four pesticides in chrysanthemum were determined:the optimum extraction conditions were pressure 400 bar,temperature 50℃,CO₂ Volume 40 mL,modifier acetonitrile.2.Purification conditions:Florisil,Al₂O₃,NH₂,five eluents:ethyl acetate/n-hexane（5:95,V/V）,ethyl acetate/n-hexane（20:80,V/V）,ethyl acetate/n-hexane（30:70,V/V）,ethyl acetate/n-hexane（50:50,V/V）and dichloromethane/n-hexane（80:20,V/V）The elution curves of four pesticides were tested.Finally,Florisil column was selected,and the eluent was ethyl acetate/n-hexane（50:50,V/V）.3.GC-MS method was developed for the simultaneous determination of chlorpyrifos,metalaxyl,Kungfu and fenvalerate in chrysanthemum:GC conditions:chromatographic column:hp-5ms capillary column（35m×0.25 mm×0.25μm）;column temperature program:initial temperature 50℃（holding for 1 min）,20℃/min to 150℃,holding for 5 min,then 10℃/min to 250℃,and the final temperature for 5min;MS（EI）conditions:ion source temperature:200℃;acquisition mode:Sim;solvent delay:3 min;electron impact ionization voltage:70 e V;scanning rate:1.5 scan/s;scanning mass range:40-600 m/z.4.Compare the supercritical fluid extraction and traditional solvent extraction of chrysanthemum samples.The recoveries of supercritical fluid extraction were 77.97%-110.34%and RSD values were 3.79%-13.95%in the range of 0.1,0.5 and 2 mg/kg in supercritical fluid extraction,and the recoveries of traditional solvent extraction were70.91%-103.96%and 5.68%-10.37%respectively.The two extraction methods of pesticide residues can meet the requirements of supercritical extraction.A rapid and accurate method for the determination of four pesticide residues in Chrysanthemum by supercritical CO₂ extraction and gas chromatography-mass spectrometry was established.The sensitivity,accuracy and precision of the experimental method met the requirements of pesticide residue analysis.