| Summary: | In order to establish a rapid, efficient and convenient method for the determination of 19 phthalate esters in vegetable oil, a method for the determination of 19 phthalate acid esters in vegetable oil by freezing method combined with GC-MS/MS was developed. The results showed that: the pretreatment method of freezing for 24 hours at –18 ℃ was changed to freezing for 12 hours at –36 ℃ which could reduce the sample pretreatment time. In addition to the determination of 8 phthalate ester compound in LS/T 6131—2018, this method also determined 11 phthalate ester compounds, including DAP, DMEP, BMPP, DEEP, DPP, DHXP, BBP, DBEP, DPhP, DNOP and DNP. Compared with the external standard method of LS/T 6131—2018, this method added the isotope internal standard method. GC-MS/MS was used to compare differences between the internal standard method and the external standard method in determining the content of phthalate esters in vegetable oil.The results showed that there was a good linear relationship between the chromatographic peak responses values of 19 phthalate esters in vegetable oil on GC-MS/MS and their mass concentrations. The correlation coefficients of the regression curve equations of the external standard method and the internal standard method were greater than 0.990, and the detection limit and quantitative limit were lower than LS/T 6131-2018. The method met the requirements of 19 PAEs analysis. The precision and accuracy of internal standard method are better than that of external standard method, mainly because the internal standard method can avoid the content loss in the extraction process. The experimenter can use the corresponding quantitative method according to the actual situation.
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