Development of Certified Reference Materials of Phthalates in Soils

Phthalates (PAEs) are a class of organic pollutants that are continuously released and present in the environment and are listed as priority-controlled pollutants. Soil is one of the main final fates of PAEs in the environment, and China has fully launched investigations and controls on soil pollution of PAEs. Analysis is the foundation of environmental monitoring and scientific research, and the certified reference materials in soil are important means to ensure the accuracy and reliability of determination for soil. However, the existing relevant reference materials do not meet the actual needs of pollution monitoring in China. In this study, according to the characteristics of PAEs pollution and quality control requirements of actual samples, four certified reference materials for PAEs analysis in soils have been developed through the nine laboratories’ collaborative analysis. The candidates were mainly collected from agricultural soils, plastic film mulched soil, industrial soil, and plastic recycling station soil. After homogeneity and stability testing, the results show that both homogeneity and stability meet the requirements. During the certification process, in response to the difficulty of controlling the PAEs analysis blank, the pollution source of the blank was identified and confirmed, and strict quality control measures were formulated to ensure that the blank concentration throughout the entire process remained stable within a certain range. Nine laboratories used gas chromatography-mass spectrometry (GC-MS) to collaboratively determine the values of 4 PAEs and evaluated their uncertainty in soils. The certified values of 4 PAEs in soils ranging from 36g/kg to 2.87mg/kg. The authoritative domestic laboratory used isotope dilution mass spectrometry to verify the accuracy of the certification results. This series of reference materials have been approved as a national first-class reference material, numbered from GBW07595 to GBW07598, which meets the requirements of PAEs analysis quality assurance and quality control, and provides technical support for ecological geological survey and evaluation.