Study of interaction between cationic surfactant (CTAB) and ascorbic acid/ascorbic acids derivatives by tensiometric and spectroscopic methods

Abstract

The interactions between the cationic surfactant-cetyltrimethylammonium bromide (CTAB) and ascorbic acid and its derivatives in an aqueous media were investigated by using tensiometric and spectroscopic methods. On the basis of the surface tension isotherms, the values of the critical micelle concentration were determined also the adsorption parameters (the Gibbs free energy of adsorption, the surface excess at the saturated interface, the minimum molecular area in the adsorption layer at the saturated interface) were calculated using the Szyszkowski equation. The charged pseudophase model was adopted for define the Gibbs free energy of micellization. The infrared analysis (FTIR) contributed to the estimation of the possibility of the existence of interactions prevailing in the analyzed systems. The effect of CTAB-ascorbic acid/ascorbic acid derivatives interactions on their antioxidant activity was analyzed. Sets of ascorbic acid, 3-O-ethyl ascorbic acid and ascorbyl glucoside solutions differing in CTAB concentration were prepared. For the total antioxidant capacity determination, the Ferric Reducing Antioxidant Power (FRAP) assay and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) assay were used. The results obtained for CTAB - ascorbic acid/ascorbic acid derivatives systems were compared with the ones obtained for pure antioxidants.