EFFECT OF IONIC STRENGTH AND ACTIVE ACIDITY OF THE MEDIUM ON THE STABILITY OF VITAMIN E NANOEMULSIONS (ALPHA-TOCOPHEROL ACETATE)

Abstract

In this work, the influence of the ionic strength and active acidity of the medium on the stability of vitamin E (alpha-tocopherol acetate) nanoemulsions was studied. Vitamin E nanoemul- sions were obtained by mixing an aqueous solubilizer solution with vitamin E. Nonionic surfactants Tween 80 and Kolliphor HS 15 were used as solubilizers. The obtained samples were studied by dynamic light scattering on a Photocor-Complex device. It has been established that samples of vitamin E nanoemulsions have a monomodal size distribution. The hydrodynamic radius of vitamin E micelles obtained with Kolliphor HS 15 is 12 ± 4 nm, and with Tween 80 it is 160 ± 21 nm. The study of the influence of ionic strength on the stability of vitamin E nanoemulsions showed that in the range of ionic strength from 0.1 to 3.0 mol/dm3, there are no significant changes in the hydrodynamic radius of vitamin E micelles, and with an increase in ionic strength up to 5.0 mol/dm3 “jumping” change in the hydrodynamic radius of vitamin E micelles when using both nonionic surfactants. It has been shown that at pH > 9, the hydrodynamic radius of micelles of vitamin E nanoemulsion obtained using Kolliphor HS 15 increases from 12 to 255 nm, which is associated with alkaline hydrolysis of ether groups of Kolliphor HS 15. Nanoemulsions of vitamin E solubilized in Tween 80 micelles are stable over the entire pH range from 1.65 to 12.43.