Development of a sensitive method for the quantitative analysis of 34 organophosphate esters in seabird eggs, liver, and fish liver tissue

Mandana Barghi ¹ Eric Fries ¹ Rahmi Chowdhury ¹ Jennifer Provencher ² Mark Mallory ³ Bonnie M Hamilton ^4,5 Roxana Suehring ^6*

• ¹ Toronto Metropolitan University, Toronto, Ontario, Canada
• ² Environment and Climate Change Canada, Ottawa, Canada
• ³ Acadia University, Wolfville, Nova Scotia, Canada
• ⁴ Environment and Climate Change Canada, Egbert, Canada
• ⁵ University of Toronto, Toronto, Ontario, Canada
• ⁶ Ryerson University, Toronto, Canada

Organophosphate esters (OPEs) are a diverse group of synthetic organic chemicals used in a variety of plastics as plasticizers and flame retardants, among other application OPEs were initially considered to pose minimal environmental risk. However, there has been increasing evidence that OPEs are present in high concentrations in remote areas such as the Canadian Arctic, including in organisms such as seabirds through long-range transport in air, water, and associated to plastic particles. Moreover, many Arctic seabirds with high loads of ingested plastics also have elevated concentrations of OPEs, suggesting that plastics containing OPEs might act as sources of OPEs in biota. Further research into OPE mixtures to which biota are exposed is warranted. Existing methods for OPE analysis in biota typically cover fewer than 20 OPEs and few tissue types. Here we present a method for the analysis of 34 OPEs in seabird eggs and liver tissue, and fish liver tissue using ultrasound assistant extraction, solid-phase extraction as clean-up and high-performance liquid chromatography coupled with atmospheric pressure chemical ionization high-resolution mass-spectrometry. The validated method showed good linearity (R2 > 0.99), average recoveries for native and isotope-labelled analytes between 70% and 120%, and inter-day precision of between 1.87% and 21.7% (median = 7.49%). The variety of OPEs included in this new method enables the investigation of OPEs with a broad range of physical-chemical properties and applications in biota samples. The detection of highly non-polar OPEs in Arctic biota tissue highlights the need for further investigation of the bioaccumulation potential of these substances. Moreover, the high detected concentrations of up to 147 ng g-1 ww of the OPE metabolite Bis(1,3-dichloro-2-propyl) phosphate (BDCP) in livers of Arctic seabirds show that these animals were exposed to chlorinated OPEs even if they were not detectable in the tissue.