Food Safety and Environmental Stewardship Program

Interest in phthalate detection of foods and other environmental media has grown rapidly in the past decade. However, current analytical and separation techniques are often limited in the breadth of chemistry targeted, most often targeting less than 15 compounds. Challenges to successful methods with this compound group include chromatographic resolution, quantitation across diverse concentration ranges, and sample preparation due to the chemical similarity of these compounds. This project describes the development of a selective ion monitoring gas chromatography mass spectrometry method for quantitation of 29 phthalates and two phthalate replacements along with considerations for quantitation, sample cleanup, and standard storage. Our range of phthalates includes less-studied ones like bis(2-propylheptyl), diundecyl, didecyl, and ditridecyl. Analytical performance included limits of detection ranging from 17–230 ng/mL and robust reproducibility with relative percent differences below 8% for complex matrices. Two calibration ranges were used to accommodate the wide dynamic range of phthalate concentrations observed in real samples. Method application was demonstrated with edible oils (n = 12) and silicone wristbands (n = 18), representing dietary and personal exposure pathways. Sample preparation strategies, including solid phase extraction were evaluated to mitigate matrix interferences. In addition, compound storage stability was assessed over 133 days to inform best practices for standard preparation and handling. The finalized method demonstrates the uniquely large compound ranges for some phthalates and the importance of analyzing a wide variety of these compounds, making it a valuable foundation for comprehensive environmental monitoring of phthalates and their alternatives.