National Fish and Wildlife Forensic Laboratory, 1490 E. Main St., Ashland, OR 97520, USA.
Universidad Mayor, Chile.
Rapid Commun Mass Spectrom. 2020 Dec 15;34(23):e8916. doi: 10.1002/rcm.8916.
The keratin fleece of the endangered vicuña (Vicugna vicugna) commands a high value in international markets, and this trade has caused illegal poaching and a substantial decrease in vicuña populations. Morphological analysis of hairs does not have the resolution to determine the species of origin of camelid natural fibers. In addition, commerce in camelid fleece also includes the legal trade of alpaca (Vicugna pacos) and guanaco (Lama guanicoe) wool.
The keratin fiber spectra of vicuña (n = 19), guanaco (n = 20) and alpaca (n = 20) were collected using X-ray fluorescence (XRF) spectrometry, Horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy and direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS). Analysis with each technique evaluated the data to determine if the three taxa could be separated using either descriptive or multivariate statistics.
XRF analysis showed that the elements detected and their relative concentrations were similar in all three species, whereas HATR-FTIR analysis could identify alpaca fleece but could not differentiate vicuña from guanaco. Ions detected by ambient ionization using DART-TOFMS, in either positive- or negative-ion mode, gave the best results and showed that each taxonomic group is distinctive. Multivariate analysis of the mass spectra created robust models which resolved each species (LOOCV = 99.9%). The analyses of eight validation samples were correctly assigned to the appropriate species and demonstrated the reliability of DART-TOFMS to infer taxonomic source.
The DART-TOFMS spectra of unmodified keratin fibers infer that the chemotype of each species is heavily influenced by fatty acids, cholesterol and its analogs, and that these ions are useful in separating the fleece of vicuña, alpaca and guanaco. We posit that the etiological source of these chemotype differences is consistent with genetic modulations and is less influenced by diet. Accurate taxonomic identification of fleece is important to identify violations and assists in the protection of rare species.
濒危的小羊驼（Vicugna vicugna）的羊毛在国际市场上价值很高，这种贸易导致了非法偷猎和小羊驼数量的大量减少。毛发的形态分析没有分辨率来确定骆驼科天然纤维的起源物种。此外，骆驼科羊毛的商业交易还包括羊驼（Vicugna pacos）和原驼（Lama guanicoe）羊毛的合法贸易。
使用 X 射线荧光（XRF）光谱法、水平衰减全反射傅里叶变换红外（HATR-FTIR）光谱法和实时直接分析飞行时间质谱（DART-TOFMS）收集了 19 只小羊驼、20 只原驼和 20 只羊驼的角蛋白纤维光谱。每种技术的分析都评估了数据，以确定这三个分类群是否可以使用描述性或多元统计数据进行分离。
XRF 分析表明，三种物种检测到的元素及其相对浓度相似，而 HATR-FTIR 分析可以识别羊驼的羊毛，但无法区分小羊驼和原驼。使用 DART-TOFMS 进行环境电离检测到的离子，无论是正离子模式还是负离子模式，都能得到最好的结果，并表明每个分类群都是独特的。对质谱的多元分析创建了强大的模型，可以分辨出每个物种（LOOCV=99.9%）。对 8 个验证样本的分析正确地分配到了适当的物种，证明了 DART-TOFMS 推断分类来源的可靠性。
未经修饰的角蛋白纤维的 DART-TOFMS 光谱表明，每个物种的化学型都受到脂肪酸、胆固醇及其类似物的强烈影响，这些离子可用于分离小羊驼、羊驼和原驼的羊毛。我们推测，这些化学型差异的病因来源与遗传调控一致，受饮食影响较小。对羊毛的准确分类鉴定对于识别违规行为和保护稀有物种很重要。
