| The safety of edible oils is closely bound up with public life.Benzo[a]pyrene(BaP)and phthalate esters(PAEs),two common pollutants,studied in this study widely exist in edible oils.In recent years,there are following questions exist in analysis methods of BaP and PAEs in edible oils.It is organic reagent-consuming,labor-intensive and expensive in the process of pretreatment.Furthermore,there are many kinds of PAEs,some of them can not be qualitatively and quantificationally analyzed due to the lack of corresponding standard compounds.And the research data about PAEs pollution situation in edible oils is serious lack.To solve above problems,phase-transfer catalyst(PTC)is added into the system of edible oil-KOH aqueous solution in this study,which not only accelerate the hydrolysis rate,but also reduce the consumption of organic reagents.BaP in the hydrolysate of edible oils was extracted by supramolecular solvent-based microextraction(SUSME),the purification effect of is achieved at the same time of extraction due to the restricted access property of supramolecular solvent.Phthalic acid(PA),the ramification of PAEs,is enriched by liquid phase microextraction(LPME)efficiently.And the total PAEs in edible oils were determined,which assessing the pollution level of PAEs in edible oil accurately.This work mainly studies the technique application of phase transfer catalyst assisted saponification for the determination of BaP and the total PAEs in edible oils.The specific research content is divided into the following two parts:1.A new analytical method for the rapid determination of BaP in edible oils was developed by using PTC assisted saponification before SUSME coupled with HPLC-FLD.Different parameters affecting the saponification and SUSME procedures,such as the concentration of the aqueous KOH solution,the type and volume of protic solvents,the type and amount of PTCs and alkyl alcohols,the volume of THF,and the extraction time were investigated.Under the optimal conditions,the method offered excellent linearity over a range of 0.03~1.0 ng mL-1(r>0.999),recovery rates varied from 94% to 102% with RSDs <5.0%,the detection limit and quantification limit were 0.06 μg kg-1 and 0.19 μg kg-1,respectively.The proposed method was applied for the analysis of 52 edible oils,the contents of BaP ranged from <LOQ to 28.54 μg kg-1.The BaP contents of 23 tested oil samples exceeded the maximum limit of 2 μg kg-1 for BaP set by the Commission Regulation of the European Union,while 3 tested oil samples exceeded the maximum limit of 10 μg kg-1 set by national standard in China.2.The pretreatment method established by the laboratory was applied to determination and assessment of PAEs pollution in edible oils,involving PTC assisted saponification and purification with n-hexane before LPME.And analytes were analyzed by HPLC-DAD.The results showed that the contents of total PAEs in 125 edible oil samples ranged from <LOQ to 366.68 μmol kg-1,the average and median content was 8.45 and 3.56 μmol kg-1,respectively.According to analysis and comparison of the data,it could be found that the type of edible oils have a certain degree of effect,while no significant difference was observed among different packaging materials.This method is advantageous to investigate and monitor PAEs in large quantities of edible oil samples,providing the basis for research of PAEs pollution in domestic and international edible oils. |
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