Department of Chemistry, Faculty of Engineering , Istanbul University-Cerrahpasa , Avcilar 34320 , Istanbul , Turkey.
Department of Analytical Chemistry, Faculty of Pharmacy , Ataturk University , 25240 , Erzurum , Turkey.
J Agric Food Chem. 2019 Jul 24;67(29):8279-8289. doi: 10.1021/acs.jafc.9b03001. Epub 2019 Jul 15.
This study is focused on examining the tocopherol isomers (α-, γ-, and δ-) fingerprinting by online RP-HPLC analysis with post column detection using CUPRAC (cupric reducing antioxidant capacity) methodology for argan oil authenticity. The proposed online assay was validated with good precision, reproducibility, and linearity. Sixteen argan oil samples (100% pure-certified and other commercial argan oils), possible adulterating vegetable oils (i.e., olive, sunflower, corn, and soya oils), and virgin argan oil blended with olive, sunflower, corn, and soya oils at levels of 5%, 10%, 15%, and 20% were analyzed. Spectrophotometric CUPRAC, DPPH, and ABTS assays were applied. Discrimination of fraudulent argan oils from virgin samples was performed by utilizing orthogonal partial least-squares discriminant analysis (OPLS-DA) regression modeling with good sensitivity and specificity. We suggested [γ-toc/α-toc] value as a new first screening adulteration factor (AF) that could be used to assess fraudulent argan oil samples. The distinct decrement in AF value was observed by the increase of adulteration rate. The AF values for virgin argan oils were ranged from 11.8 (lower limit) to 18.6 (upper limit). The presence of β-sitosterol detected in commercial argan oils (with AF values out of limit values) was evaluated as fraudulent which was in accordance with the proposed assay. Our method enabled the detection of argan oil samples at adulteration levels of >5% in the case of sunflower, olive, and soya oils, >15% in the case of corn oil. This method may be an alternative and specific assay for the authentication and quality detection of commercial argan oils.
本研究专注于通过在线反相高效液相色谱分析（RP-HPLC）并结合铜还原抗氧化能力（CUPRAC）法后柱检测来检测角鲨烯异构体（α-、γ-和 δ-）指纹图谱，以鉴定阿甘油的真伪。所提出的在线分析方法具有良好的精密度、重现性和线性。分析了 16 种阿甘油样品（100%纯认证和其他商业阿甘油）、可能掺假的植物油（如橄榄油、葵花籽油、玉米油和大豆油）以及与橄榄油、葵花籽油、玉米油和大豆油以 5%、10%、15%和 20%的比例混合的初榨阿甘油。应用分光光度法 CUPRAC、DPPH 和 ABTS 测定法。利用正交偏最小二乘法判别分析（OPLS-DA）回归建模对欺诈性阿甘油与初榨样品进行了区分，具有良好的灵敏度和特异性。我们建议[γ-生育酚/α-生育酚]值作为一种新的初筛掺假因子（AF），可用于评估欺诈性阿甘油样品。随着掺假率的增加，观察到 AF 值明显下降。初榨阿甘油的 AF 值范围为 11.8（下限）至 18.6（上限）。商业阿甘油中存在的β-谷甾醇（AF 值超出限值）被评估为欺诈性，这与所提出的检测方法一致。在橄榄油、葵花籽油和大豆油的掺假水平>5%的情况下，在玉米油的掺假水平>15%的情况下，本方法可用于检测阿甘油样品。该方法可能是商业阿甘油认证和质量检测的替代和特定方法。
