The Application Of Gas Chromatography In Food Analysis

Nowadays more and more attention has been paid to food safety and foodnutrition problem. The harmful substances in food come from the following3kinds ofsources: food raw materials, external pollution, component conversion. Food analysisis one of the main measures to control food safety and to ensure food quality. It isnecessary to develop reliable, effective, and accurate analytical methods for thedetermination of pesticides, veterinary medicines, food additives and other harmfulingredients or food nutrients, in order to guarantee food safty for people.The thesis is divided into six parts:Part I: A review of the application of a variety of sample pre-treatment methodsin gas chromatography analysis and food safety testing.Part II: Matrix solid phase dispersion （MSPD）-gas chromatography (GC)method was proposed to detect three organophosphorus pesticide residues includingmethamidophos, dimethoate, and chlorpyrifos in eggplant powder. The sample isgraphitized with neutral alumina, eluted with ethyl acetate，and quantified by externalstandard method. The results show that there is a good linear relationship (R~2=0.99)in the concentration range of0.02~1.0mg/L；the recoveries are84.2%~98.5%in3standard levels（0.1,0.4,0.8mg/kg）；and the detection limits are0.01,0.01,0.005mg/kg for methamidophos, dimethoate and chlorpyrifos, respectively. The method issimple and rapid, which can satisfy the testing requirements of methamidophos,dimethoate and chlorpyrifos in Eggplant powder.Part III: A gas chromatographic method for determination of cholesterol in squidwas developed. Saponification time, the concentration of the potassium hydroxide, theamount of ethanol and extraction method were investigated to optimize theexperimental conditions. The method is fast, accurate and low cost. Good linearrelationship(R~2=0.9998) in the range of100~1000mg/L was obtained. The detectionlimit is50mg/L. Cholesterol recoveries are greater than96.4%, and the relativestandard deviation was2.03%. A simple and practical analytical method is provided for the determination of cholesterol in squid.Part IV: A method for the determination of butylhydroxyanisole ether (BHA),2,6-di-tert-butylcresol (BHT) in salty peanuts by gas chromatography was developed.Soxhlet extraction method was used to extract oil in the salty peanuts, and then thetarget extracted was extracted with methanol. The detection limit of the method is0.4mg/kg, the recoveries of BHA&BHT are92.5%~102.9%with relative standarddeviation from2.46%to4.52%. BHA and BHT showed good linear relationships (R~2=0.9996) in the range of20~100μ g/mL, The method is suitable for the detection ofBHA and BHT in salty peanuts.Part V: This paper established a gas chromatography-tandem mass spectrometrymethod for the analysis of dimethyl phthalate (DMP), o-diethyl phthalate (DEP),o-phthalate, diisobutyl phthalate (DIBP), phthalic twobutyl (DBP) and ortho-phthalate,di-(2-ethyl) hexyl phthalate (DEHP) in liquor. Sample pre-treatment is simple, fastand practical. Five phthalate plasticizers （PAEs）showed good linear relationships(R~2＞0.99) in the range of0.5~50mg/mL. The recoveries of the method is84.9%to107.8%. The relative standard deviation is1.20%to8.39%, and the detection limit ofthe method is0.005mg/L. It is an effective method for the detection of five PAEs inwhite wine samples.Part VI: This part established the derivative treatment-Gas Chromatographymethod to analyse chloramphenicol content in the freeze-dried sea cucumber.Chloramphenicol showed a good linear relationship(R~2=0.9997) in the range of1.0~20mg/L.The recoveries of the method is83.3%to100.4%. The relative standarddeviation is2.60%to9.30%. The detection limit of the method is0.003mg/L. It canbe used as practical method for the detection of chloramphenicol in freeze-dried seacucumber.