Relative solubility, stability, and absorptivity of lutein and .beta.-carotene in organic solvents

The relative solubility, stability, and absorptivity of lutein and beta-carotene were determined in 18 organic solvents. The solubility of both carotenoids was greatest in tetrahydrofuran, while hexane exhibited the least solubility for lutein; methanol and acetonitrile exhibited the least solubility for beta-carotene. Stability was monitored for 10 days at room temperature by measuring absorbance changes at the wavelength maximum. In the majority of the solvents, initial absorbance decreased by less than 10% during the 10-day period. Degradation was greatest for both carotenoids in cyclohexanone. The relative absorptivities were determined by calculating the carotenoid concentration in a reference solvent using a reference absorptivity, and then Beer's Law was applied to the measured absorbance of the same carotenoid concentration in other organic solvents. Absorbance maxima and relative absorptivities were in good agreement with available literature values