Different spectrophotometric methods for simultaneous quantification of lycopene and β-carotene from a binary mixture

Abstract

UV-VIS spectrophotometric analysis is one of the cheapest and most handy methods used for carotenoids quantification in solutions. According to Lambert-Beer's law, carotenoids concentrations in a mixture are computed using mixture absorbances and characteristic absorption coefficients for pure compounds. This work proposes four methods for simultaneous quantification of two carotenoids using mixture spectral data, physical models of pure and mixtures spectra in acetone-hexane mixture, different wavelengths groups for absorbance of each carotenoid, the spectra overlapping property and isosbestic point presence. Two absorbance factors defined to improve the concentrations equations accuracy and different assumptions in terms of wavelengths groups and contribution of each carotenoid at mixture absorbance are considered. These methods are validated using synthetic mixtures for two carotenoids (lycopene and β-carotene) and two tomato residue extracts using equivalence test as statistical tool. IPM–II–WG6 method gives good correlation from statistical point of view, with medium accuracy errors.