Reference Method of Measurements of the Content of Phthalates in Polymer Matrices: Analytical and Metrological Approaches

The article considers the problems of environmental pollution by phthalates and the impact of phthalates on human health. The article describes the process of developing a reference method of measurements (RMM VNIIM-243-01-2019) of the mass fraction of esters of ortho-phthalic acid (dimethyl phthalate, diethyl phthalate, di(n-butyl) phthalate, benzylbutyl phthalate, di(2-ethylhexyl) phthalate and di(n-octyl) phthalate) in polymer matrices based on polyvinyl chloride by isotope dilution gas chromatography/mass spectrometry. The stages of the measurement procedure and ways of optimizing them in order to improve the measurement results accuracy are discussed. The sources of uncertainty are studied and the contributions of all components to the total standard uncertainty of the RMM measurement results are minimized. The metrological characteristics of RMM have been established: the measurement range is 10–5000 mg/kg; the standard deviations under conditions of repeatability and intermediate precision are 2 and 3%, respectively; the relative extended uncertainty is 6–8%. The method is intended to establish the metrological characteristics of reference materials of matrices, examine the correctness of the measurement results obtained using other techniques (methods) for measuring similar quantities, and perform measurements for arbitration purposes. The results of key international comparisons CCQM-K133 “Phthalate esters in Polyvinyl Chloride (PVC)” are presented as an objective confirmation of compliance with the RMM.