*4.3. Determination of Antioxidant Activity of the Formulations*

Antioxidant activity of the formulations was determined on a model of linetol peroxidation containing a complex mixture of ethyl esters of polyunsaturated fatty acids (oleic, linoleic, and linolenic) of linseed oil at 37 ◦C [30]. Stock solutions of Ech, Asc, and Toc were prepared at a concentration of 10 mg/mL in ethanol. Two-component and three-component antioxidant compositions were obtained by mixing the volumes of stock solutions in the indicated proportions. First, 10 μL of each solution and 300 μL of linetol were placed in a glass vial. The reaction vessels were placed in an incubator (37 ◦C). The concentration of antioxidant in linetol in all cases was 0.05 mg/mL, or 0.005%. The mass of the reaction mixtures pre-cooled to room temperature was measured twice a day (accuracy 0.0005 g). When the mass of increased by 10 mg, the reaction was stopped. All of the experiments were repeated three times. The period of linetol oxidation inhibition (Δτ) was calculated as the difference between times necessary for the weight of linetol to increase by 10 mg in experiments with and without the addition of antioxidants using the formula Δτ = τ − τ0, where τ is the time of linetol oxidation initiation in the presence of an antioxidant (h); and τ<sup>0</sup> is the time of linetol oxidation initiation without the addition of an antioxidant (h).
