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Contemporary Fraction of bis(2-ethylhexyl) Phthalate in Stilton Cheese by Accelerator Mass Spectrometry



Michael A. Nelson, John M. Ondov, Michael C. VanDerveer, Bruce A. Buchholz


Measurements of the 14C abundance in five samples of bis(2-ethylhexyl) phthalate (DEHP) isolated from Stilton cheese were made by Accelerator Mass Spectrometry (AMS) to determine the fraction of carbon originating from contemporary biogenic sources. DEHP is classified as a “priority hazardous substance” by the EU, a probable human carcinogen by the U.S. EPA, and suspected to be a human endocrine disrupter. Measurement of its 14C abundance in a specific food indicates whether its presence is due to contamination from industrially-synthesized DEHP or a naturally inherent component. A method was developed to determine the contemporary carbon fraction of DEHP in a fatty food matrix at concentrations ≤0.14 mg/kg. Five ~90 µg quantities of DEHP were extracted from 12 kg of Stilton cheese and isolated by silica gel, size exclusion, and C18 HPLC chromatography. Masses of samples were determined by both GCMS analyses prior to combustion and manometry afterwards. The purity of DEHP carbon mass in each isolate was determined by multivariate deconvolution of GC-MS fragmentation spectra obtained from measurements of standards and isolates. These ranged from 88.0 ± 1.8% to 92.3 ± 1.1 %. Concurrently processed isolation method blanks contained from 0.15 ± 0.04 µg to 1.52 ± 0.06 µg DEHP per sample and significant quantities of pre- and post-chromatographic extraneous carbon contamination. The mean 14C-corrected contemporary carbon fraction of DEHP in the isolates was 0.235±0.073 (1 σ; and ±0.091 at the 95% confidence level), revealing that the majority of DEHP in Stilton cheese results from anthropogenic sources, but with a significant naturally occurring component.




Nelson, M. , M., J. , VanDerveer, M. and Buchholz, B. (2013), Contemporary Fraction of bis(2-ethylhexyl) Phthalate in Stilton Cheese by Accelerator Mass Spectrometry, Radiocarbon (Accessed May 23, 2024)


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Created May 17, 2013, Updated January 27, 2020