Forensic characterization of sea turtle oil by ambient ionization mass spectrometry: Caretta caretta, Chelonia mydas, Dermochelys coriacea, Eretmochelys imbricata, Lepidochelys kempii, and Lepidochelys olivacea

Abstract

Historically the oils from sea turtles have had a high commercial demand, and this trade has contributed to an alarming decrease in sea turtle populations worldwide. Determining the species source of seized animal oils is challenging and this has hindered enforcement of the ban on trade in sea turtle oil. In this work we investigate if the chemotypes obtained from ambient ionization mass spectrometry analysis can assist in making species classifications of oil. Oil was either obtained or yielded from tissue from Green sea turtle (Chelonia mydas), Loggerhead sea turtle (Caretta caretta), Kemp's Ridley sea turtle (Lepidochelys kempii), Olive Ridley sea turtle (Lepidochelys olivacea), Hawksbill sea turtle (Eretmochelys imbricata), and Leatherback sea turtle (Dermochelys coriacea). Additionally, common oils from vegetable and animal sources were investigated to determine if any other oil sources could be confused with sea turtle oils. The oil samples were ionized both in the positive and negative mode by Direct Analysis in Real Time (DART) and the masses were measured in a time of flight mass spectrometer (AccuTOF by JEOL). Positive and negative mode mass spectra produced species-specific chemotypes and no other oils analyzed in this study produced chemotypes resembling those of sea turtle oils. We conclude that this approach is accurate and very useful for rapidly characterizing neat sea turtle oils without the need for sample derivatization.