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

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.

长期以来，海龟油拥有极高的商业需求，此类贸易已导致全球海龟种群数量出现令人担忧的下滑。要确定查获的动物油脂的物种来源颇具难度，这也阻碍了海龟油贸易禁令的执法执行。本研究旨在探讨通过环境电离质谱分析获取的化学型（chemotypes）是否能够辅助实现油脂的物种分类。本研究的油脂样本均取自绿海龟（Chelonia mydas）、蠵龟（Caretta caretta）、肯氏丽龟（Lepidochelys kempii）、榄蠵丽龟（Lepidochelys olivacea）、玳瑁（Eretmochelys imbricata）以及棱皮龟（Dermochelys coriacea）的组织。此外，本研究还对常见的植物源及动物源油脂开展了检测，以排查是否存在其他油脂来源会与海龟油产生混淆。本研究采用实时直接分析电离源（Direct Analysis in Real Time, DART）对油脂样本分别实施正、负离子模式电离，并通过飞行时间质谱仪（日本电子JEOL的AccuTOF）完成质量数检测。正、负离子模式下得到的质谱均可生成物种特异性化学型，且本研究中检测的其他油脂均未产生与海龟油相似的化学型。本研究结论表明，该方法无需对样本进行衍生化处理，即可快速精准表征纯海龟油脂，兼具极高的准确性与实用性。