Aprotic solvents effect on the UV-visible absorption spectra of bixin.
We describe here the effects of aprotic solvents on the spectroscopic characteristics of bixin. Bixin was dissolved in dimethyl sulfoxide, acetone, dichloromethane, ethyl acetate, chloroform, dimethyl carbonate, cyclohexane and hexane, separately, and its spectra in the resulting solutions were determined by UV-visible spectrophotometry at normal pressure and room temperature. We analyzed the effect of aprotic solvents on λmax according to Onsager cavity model and Hansen theory, and determined the approximate absorption coefficient with the Beer-Lambert law. We found that the UV-visible absorption spectra of bixin were found to be solvent dependent. The S0→S2 transition energy of bixin in solution was dependent principally on the refractive index of the solvents and the bixin-solvent dispersion interaction. There was a small influence of the solvents dielectric constant, permanent dipole interaction and hydrogen bonding occurred between bixin and solvents. The absorbance of bixin in various solvents, with the exception of hexane, increased linearly with concentration.
Université de Toulouse, INP-ENSIACET, LCA (Laboratoire de Chimie Agro-industrielle), 4 Allée Emile Monso, CS 44362, 31030 Toulouse Cedex 4, France; Departement of Chemistry, Mathematic and Natural Science, Tanjungpura University, Jl. Ahmad Yani, Pontianak 78124, West Kalimantan, Indonesia.
Winda
W
Rahmalia
Université de Toulouse, INP-ENSIACET, LCA (Laboratoire de Chimie Agro-industrielle), 4 Allée Emile Monso, CS 44362, 31030 Toulouse Cedex 4, France.
Jean-François
JF
Fabre
Departement of Chemistry, Mathematic and Natural Science, Tanjungpura University, Jl. Ahmad Yani, Pontianak 78124, West Kalimantan, Indonesia.
Thamrin
T
Usman
Université de Toulouse, INP-ENSIACET, LCA (Laboratoire de Chimie Agro-industrielle), 4 Allée Emile Monso, CS 44362, 31030 Toulouse Cedex 4, France; INRA, UMR 1010 CAI, F-31030 Toulouse, France. Electronic address: zephirin.mouloungui@ensiacet.fr.
Zéphirin
Z
Mouloungui
D031212:Bixaceae / Q000737:chemistry*; D002338:Carotenoids / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D012031:Refractometry; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
D004396:Coloring Agents; D012997:Solvents; D002338:Carotenoids; C004588:bixin
Absorption coefficient; Bixin; Dispersion; Refractive index