Analytical Profiling and Adulteration Detection in Nigerian Palm Kernel Oil Using Nuclear Magnetic Resonance Spectroscopy and Chemometric Methods

Palm kernel oil is a commercially valuable product of Nigeria's oil palm industry, but adulteration with lower-cost oils including soybean, sunflower, and refined vegetable oils is reportedly widespread and undermines export credibility and consumer safety. This study develops an analytical profiling and adulteration detection methodology for palm kernel oil using proton and carbon-13 nuclear magnetic resonance spectroscopy combined with chemometric methods. A total of 60 palm kernel oil samples were collected from mills in Cross River, Imo, and Akwa Ibom States, South South and South East Nigeria. NMR spectra were acquired on a 400 MHz spectrometer following dissolution in deuterated chloroform. Relevant chemical shift regions corresponding to triacylglycerol profiles, fatty acid composition, and minor components were assigned. A principal component analysis and partial least squares discriminant analysis model was built to discriminate authentic palm kernel oil from adulterated samples. Adulteration levels of 5, 10, 20, and 30 percent with three adulterant oils were tested in prepared mixtures. The NMR fingerprint method achieved correct classification of authentic versus adulterated samples with 96 percent accuracy. Partial least squares regression models for quantitative adulteration prediction showed root mean square errors of prediction of 1.8 percent adulteration level. The method was validated against gas chromatography-based fatty acid profiling as a reference. The study establishes a rapid, non-destructive authentication platform for Nigerian palm kernel oil, with direct relevance to export quality certification and NAFDAC enforcement. Keywords: palm kernel oil, NMR spectroscopy, adulteration detection, chemometrics, authentication