Near infrared spectroscopy (NIRS) reflectance technology for determination of tocopherols in animal feeds

The Vitamin E (α-, (β + γ)- and δ-tocopherol) contents present in feeds of different textures used in animal feed were analysed using near infrared spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe. The range of Vitamin E was 0.06 and 1.87 mg/100 g. The regression method employed was modified partial least squares (MPLS). The equations developed using the fiber-optic probe for 44 samples to determine the content of Vitamin E in feeds, in prediction, had multiple correlation coefficients (RSQ) and corrected standard errors (SEP (C)): 0.792, 0.223 mg/100 g for α-tocopherol, of 0.766 and 0.022 mg/100 g for (β + γ)-tocopherol, and of 0.789 and 0.112 mg/100 g for δ-tocopherol. The predicted values of Vitamin E in feeds using NIRS technology applying the fibre-optic probe directly on the sample with neither previous treatment nor manipulation are comparable to the values obtained using the chemical method that includes alkaline hydrolysis and extraction with hexane of the vitamin from the unsaponifiable fraction before chromatographic determination.