Ayyildiz, Hamide Filiz2020-03-262020-03-2620151615-93061615-9314https://dx.doi.org/10.1002/jssc.201401377https://hdl.handle.net/20.500.12395/32133A new humic acid stationary phase was prepared by immobilizing humic acid onto aminopropyl silica via an amide linkage formation and used, for the first time, for the separation and quantification of the tocopherol compounds in cold-pressed oil samples under normalphase high-performance liquid chromatography conditions. Parameters affecting the chromatographic separation such as mobile phase composition and flow rate were optimized. By evaluating the calculations of capacity factor, asymmetry factor, resolution, selectivity factor, and theoretical plate number, the best separation was obtained with isocratic elution of n-hexane and isopropyl alcohol (99:1% v/v) at a flow rate of 1.0 mL/min. The effluent was monitored by a fluorescence detector set at excitation and emission wavelengths 295 and 330 nm, respectively. All compounds were separated in 20 min. The method was validated according to international guidelines and found to be linear in a wide concentration range, also the mean recovery of the compounds ranged from 97.9 to 99.2%, with a CV less than 2.7% in all cases. The results showed that the developed stationary phase is suitable for the separation and quantification of the tocopherol compounds in real oil samples.en10.1002/jssc.201401377info:eu-repo/semantics/closedAccessHumic acidImmobilizationNormal-phase high-performance liquid chromatographyStationary phaseTocopherolArticle38581382025557082Q2WOS:000350201900014Q2