Regularities of adsorption of water-soluble vitamins on the surface of microdispersed sintered detonation nanodiamond

Adsorption of water-soluble vitamins, including riboflavin (В₂), nicotinamide (PP, B₃), pyridoxine (B₆), cyanocobalamine (В₁₂) from water-organic solutions on microdispersed sintered detonation nanodiamond (MSDN), modified in different ways, was studied using high-performance liquid chromatography (HPLC). The effect of composition (from 5% to 80 v/v % of CH₃CN) and рН (рН 2.7/6.0) of mobile phase, as well as temperature of chromatographic column (t_c = 45/65 °C) on vitamins adsorption was studied. Nonlinear dependences of the sorbate retention factors on the acetonitrile content in the mobile phase are found out, indicating the variation of specific and non-specific interactions of vitamins with MSDN surface. Based on the obtained results, the conditions for chromatographic separation of the mixture of water-soluble vitamins in isocratic mode of HPLC on MSDN are optimized.