HPLC Determination of Beta Carotene in Tobacco Leaves with Deep Eutectic Solvent Microextraction

HPLC was applied to the determination of beta carotene in tobacco leaves with deep eutectic solvent microextraction. The deep eutectic solvent consisting of menthol and lauric acid (the molar ratio of the two substances was 2:1) was used as extractant. Amount of the deep eutectic solvent was 400 μL and extraction time was 3.0 min. Agilent Zorbax SB-C₁₈ chromatographic column was used as separation column, and the mixture of methanol and isopropanol (70+30) was used as mobile phase. Detection at 448nm was adopted in the determination. Linear relationship between values of peak area and mass concentration of beta carotene was kept in the range of 0.050-9.000 mg·L^-1, with detection limit (3S/N) of 40 μg·L^-1. The proposed method was applied to the analysis of samples of tobacco leaves, giving values of recovery found by standard addition method and RSDs (n=5) of determined total amounts in the ranges of 70.2%-112% and 1.5%-3.7% respectively.