Studys On The Determination Methods Of PCBs In Foods

This thesis mainly studies the determination methods of polychlorinated biphenyls(PCBS) in food. The determination methods of polychlorinated biphenyls (PCBS) content infood at present mainly includes：solid phase extraction-gas chromatography and solid phaseextraction-gas chromatography-mass spectrometry. Experiments are carried out with thetwo methods respectively in this essay, taking fish as their measuring objects,and it stressesthe improvements of pretreatment part.1、The research on gas chromatography uses ultrasonic to extract fish samples. Theresearch results show that: The optimum extraction conditions includes:5.0g of fish samplesis extracted with30mL of n-hexane, with extraction temperature of35℃, ultrasonicpower of90kHz,120mins of ultrasonic time.The recoveries of this method variedfrom76.0%to96.7%, with an average of84.50%. When the concentration of PCBs is below0.08μg/mL, the linear correlation coefficient of standard curve is0.9966(n=4).2、Research on the determination of polychlorinated biphenyls (PCBS) in the fish withGC-MSD uses microwave assisted extraction-solid phase extraction purification method toexplore ultrasonic conditions’ influence on measurement results. The optimum determinationconditions are:10.0g of samples with10ml of V (n-hexane): V (acetone)=1:1mixture asextracting solvent, microwave extraction temperature at100℃, the extraction time of16min.The recovery ratio is88.3%~88.3%, relative standard deviation is between4.36%~7.21%,which can guarantee the qualitative and quantitative detection of4kinds of PCBs residues inthe samples.3、Taking gas chromatography and gas chromatography-mass spectrometry methods ofstable isotope dilution in GB (national standard) to determine the content of polychlorinatedbiphenyls (PCBS) in fish, by comparing and analyzing the determination results of the studiesin this essay on gas chromatography and gas chromatography-mass spectrometrydetermination, it is concluded that the ultrasonic extraction-gas chromatography method, asa feasible method for determination of polychlorinated biphenyls (PCBS) in fish, is easy tohandle. Microwave assisted extraction-solid phase extraction purification-gaschromatography-mass spectrometry method effectively shortens the testing time and theresults are accurate, which establishes a method for determination of polychlorinatedbiphenyls (PCBS) in fish food.