Preparation Of Three Reference Materials Of Phthalates Acid Esters In N-Hexane

Phthalate ester plasticizers and plastics are only connected by simple chemical bonds in the combination process,and may be dissolved out when contacting substances with high oil and migrate to the environment and food,threatening food safety and causing harm to national health and environmental pollution.It is of great significance to develop relevant plasticizer standard substances,so as to provide traceability guarantee for the accuracy of relevant detection values in food and environment.According to the requirements of the technical specification of reference substances,three kinds of phthalate ester solution reference substances based on n-hexane were developed by using the existing first class reference substances.The main research results are as follows:(1)In this paper,the standard values of DEHP,DBP and BBP were 509?g/m L,511?g/m L and 496?g/m L respectively.The homogeneity of the three standard substances was tested by gas chromatography.The uncertainty introduced by the uniformity is less than one third of the expected relative standard uncertainty(2%).According to the national standard requirements for reference materials,the uniformity of the prepared reference materials can be determined to meet the requirements.(2)In this paper,the short-term and long-term stability of the three reference substances were tested by gas chromatography.The data of DEHP,BBP and DBP solutions in n-hexane showed no significant fluctuation within 7 days,and the short-term stability was qualified at50?.There was no significant change in the data of reference substances within six and a half months.The characteristic values were stable,and the long-term stability met the requirements of reference substances.(3)The comparison method with first-level reference material was used to determine the value of reference material,the Shapiro-Wilke method was used to test the normal distribution of the data,the Dixon criterion was used to test and eliminate the outliers for the data,and the analysis of variance was used to test the difference between different groups.The test results show that there is no significant difference between different groups of DEHP,BBP and DBP solution reference substances in n-hexane.(4)The uncertainty of reference substance was evaluated,and the relative synthesis standard uncertainty u C of DEHP,DBP and BBP solution in n-hexane was calculated to be1.62%,1.73% and 1.82%,respectively,and the inclusion factor k was taken as 2.The relative extended uncertainties of DEHP,DBP and BBP solutions in n-hexane are 3.24%,3.46% and3.64%,respectively,and 4%,4% and 4%,respectively,after modification.