| Polycyclic aromatic hydrocarbons (PAHs) are a kind of persistent contaminants in the environment and food, numbers of which are considered to have genetictoxicity or carcinogenicity.200 kinds of PAHs have been found. Food safety issues caused by PAHs are more common, which have become a serious threat to human health. The American Environmental Protection Agency (EPA) and the European Food Safety Agency (EFSA) have selected to monitor 16 priority PAHs, respectively in 1979 and 2008. Our country has not formulated the standard of the limit to PAHs. GB 2762-2012 "National Food Safety Standards:Limit of pollutants in food"set limit of benzo (a) pyrene (BaP) in grain, smoked meat, smoked fish and vegetable oil.In this study, applying online enrichment-purification technology, novel analysis methods have been developed to detect EPA priority PAHs and European priority PAHs in four types of food, represented by vegetable oils.These methods can be used to provide technical support to establish database of PAHs in the foodstuffs, make limited values in food and handle the food safety accidents.The main contents in this thesis are as follows:1. A rapid method was developed for the simultaneous determination of PAHs in vegetable oil by online enrichment-purification technology coupled with high performance liquid chromatography. The detected analyets contains 16 European priority PAHs and 14 EPA priority PAHs. The effect of sample plate temperature, mobile phase,velocity of flow, injection volume and sample injection time on purification were investigated. The influence of the type of analysis column, transfer time, column temperature and elution conditions on the separation were also studied. The detection was performed on ultraviolet detection and fluorescence detection(UV/FLD), choosing the best detection wavelength. External standard method was used for quantification. Meanwhile, the scope and shortcomings of this study were discussed. The results showed that the calibration curves of the 16 European priority PAHs gained good linearity with all the correlation coefficients(r2) more than 0.99. The limits of detection (LODs)were 0.02 ?g/kg?12.23?g/kg and the limits of quantification (LOQs)were 0.09?g/kg?40.98?g/kg. The recoveries of the sixteen components in the spiked samples of three levels (Low, medium and high level)were in the range of 65.3%? 110.5% with the relative standard deviation(RSDs, n=6) of 0.1%?9.8%.The calibration curves of the 14 EPA priority PAHs had good linearity with all the correlation coefficients(r2) more than 0.99.The limits of detection (LODs)were 0.01?g/kg?6.00?g/kg and the limits of quantification (LOQs)were 0.02?g/kg?20.00?g/kg. The recoveries of the sixteen components in the spiked samples of three levels (Low, medium and high level)were in the range of 72.7%?116.6% with the relative standard deviation(RSDs, n=6) of 0.1%?7.5%. The method with simple pretreatment was accurate, sensitive, reproducible and suitable for the determination of PAHs in vegetable oil. This method also can be used for routine detection.2. Using online enrichment-purification coupled with high performance liquid chromatography (HPLC) system to establish a novel method for the determination of the 15 European priority PAHs in smoked fish and smoked meat products. This study compared the effect of homogenate condition, different extraction solvents and enrichment condition on the extraction of PAHs from the samples. Various factors, which affected the separation, such as sample plate temperature, selection of chromatography column and column temperature were investigated. The detection was performed on ultraviolet detection and fluorescence detection (UV/FLD), optimizing the detection wavelength. External standard method was used for quantification. Applying FAPAS quality control samples to verify the accuracy of the method and discuss the matters needing attention and limitations of this study. The results showed that the calibration curves of the 15 PAHs showed good linearity with all the correlation coefficients(r2) more than 0.999. The limits of detection (LODs) were between 0.03 ug/kg to 8.33 ?g/kg and the limits of quantification (LOQs) were between 0.09 ?g/kg to 25.00?g/kg The recoveries of the 15 components in the three levels of spiked smoked fish samples were in the range of 67.4%?107.2% with the relative standard deviation (RSDs, n=6) from 0.2% to 7.7%. The recoveries of the sixteen components in the three levels of spiked smoked meat samples were in the range of 71.8%?110.5% with the relative standard deviation (RSDs, n=6) from 0.8% to 8.9%. The method simplified the experimental steps and had sensititye, accuracy, and good reproducibility, which can satisfy the requirement of quantitative analysis of PAHs in smoked products.3. A method for the detection of 14 EPA priority PAHs in rice, wheat flour, corn flour and other grains by online enrichment-purification coupled with high performance liquid chromatography (HPLC) was established. This research studied the influence of extraction conditions of PAHs in the grains, including the selection of extraction solvent and enrichment conditions. The chromatography conditions and detection conditions were optimized. The detection was performed on ultraviolet detection and fluorescence detection (UV/FLD). External standard method was used for quantification and discussing the deficiency of this study. The results showed that the calibration curves of the 14 PAHs showed good linearity with all the correlation coefficients (r2) more than 0.999. The limits of detection (LODs) were between 0.01 ?g/kg to 3.00 ?g/kg and the limits of quantification (LOQs) were between 0.02 ?g/kg to 10.00 ?g/kg. The recoveries of the 14 PAHs in the three levels of spiked samples were in the range of 62.8%?117.8% with the relative standard deviation (RSDs, n=6) from 0.5% to 8.7%. This method, which was simple, accurate, sensitive and reproducible, provided a new means for the determination of PAHs in grains. |
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