Analysis and Occurrence of Organophosphate Esters in Meats and Fish Consumed in the United States

Organophosphate esters (OPEs) are chemicals extensively used as plasticizers and flame retardants in commercial and consumer products. In this study, we developed and validated a method for the analysis of 13 common OPEs in meat (chicken, pork, and beef) and fish (catfish and salmon) to study their occurrence in those foods in the United States. The method was based on QuEChERS extraction with acetonitrile and automated robotic cleanup of the extracts, followed by low pressure gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis for 8 of the OPEs and ultrahigh-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis for 13 OPEs, including 8 overlapping OPEs. The developed method was validated in the muscle tissues at four spiking levels (5, 10, 20, and 40 ng/g). The background levels in the laboratory environment and materials presented a challenge for accurate quantification at low ng/g levels. UHPLC-Q-Orbitrap MS analysis was utilized to pinpoint the source of their contamination. OPEs were found in the water used in the liquid chromatography (LC) mobile phase, and flow injection analysis with organic mobile phase was suggested as an alternative to avoid OPEs contamination in LC-MS/MS analysis. The validated method was applied to the analysis of 68 real-world meat and fish samples from the U.S. markets by three instrumental methods. Tris(2-chloro-isopropyl) phosphate (TCPP), tri-n-butyl phosphate (TnBP), and triphenyl phosphate (TPP) were found in meat, and TCPP and TPP were measured in fish samples. The sum of median OPE concentrations (averaged for the three instrumental methods) measured in the meat and fish samples were 6.2 and 8.7 ng/g wet weight, respectively. No regulations on the maximum residue levels of OPEs permitted in food were found for the U.S. or other countries.