采用低共熔溶剂微萃取-高效液相色谱法测定烟叶中β-胡萝卜素的含量。以薄荷醇和月桂酸组成（两者的物质的量之比为2∶1）的低共熔溶剂为萃取剂，低共熔溶剂的用量为400 μL，萃取时间为3.0 min。以Agilent Zorbax SB-C₁₈色谱柱为分离柱，以甲醇-异丙醇（70+30）混合液为流动相，在检测波长448 nm处进行测定。β-胡萝卜素的质量浓度在0.050~9.000 mg·L^-1内与其对应的峰面积呈线性关系，检出限（3S/N）为40 μg·L^-1。方法用于烟叶样品的分析，加标回收率为70.2%~112%，测定总量的相对标准偏差（n=5）为1.5%~3.7%。

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.