Stability enhancement of fixolide by complexation with cyclodextrin

Abstract

The purpose of this study was to explore the effects of cyclodextrin on the stability of fixolide, a widely used fragrance material in personal care and household products. Soluble and solid complexes of fixolide with βCD, methyl-βCD or HP-βCD were prepared. Phase solubility diagrams suggest the formation of soluble complex of fixolide with methyl- and HP-βCD, and was classified as the A[subscript L]- and A[subscript N]-type, respectively. On the other hand, βCD showed B[subscript S]-type solubility curve with the precipitation of insoluble complex at higher βCD concentration. Solid complexes were prepared by means of co-precipitation, kneading, and freeze-drying techniques with three mole ratios of fixolide : CD of 1:1, 1:2 and 1:3. Differential Scanning Calorimeter (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) were used to comfirm the inclusion complex in solid state. The DSC curves for co-precipitation mixture of fixolide with βCD (1:2 mole ratio) did not show the endothermic peak characteristic of free fixolide and FTIR analysis showed a shift of the major peak of carbonyl group in fixolide molecule from 1683 to 1677 cm[superscript -1]. The results suggest that complete complex formation was occurred. This complex was quantified by solvent extraction method and GC analysis. It gave the highest amount of fixolide included in βCD, the value was 96.93 mg/g complex with the acceptable complex yield of 74%. When effects of temperature and light on the stability of fixolide-βCD complex both in solid state and in fabric softener were compared with free fixolide, it appears that βCD could slow down the degradation of fixolide and did not change the reaction order of degradation. Moreover, βCD and methyl-βCD could also increase dissolution of fixolide. The overall results suggest the potential use of CD in the improvement of fixolide properties for quality enhancement of industrial products containing the fixolide fragrance.