本文旨在探索出一种新的薄荷脑精致技术。选用纯度93.50%薄荷脑作为研究对象，借助外磁场协同结晶，研究了结晶温度、溶液浓度、溶剂种类、磁场方向、磁场强度、磁化时间等因素对结晶的影响，获得了较佳的电磁诱导结晶分离薄荷醇的工艺条件，产品的纯度经GC-MS分析达到99.10%，磁场强化作用显著，大大缩短结晶时间，一定程度上提高了晶体纯度。采用旋光法、热差分析法、红外光谱法和质谱法对磁性诱导所得晶体进行结构表征，旋光法分析结果表明磁性诱导后的晶体的旋光度提高（幅度分别为1.29%、2.93%、0.74%）；热差分析结果表明磁性诱导后的晶体熔程变短（幅度分别为23.77%、32.32%、30.88%），熔融焓变大（幅度分别为0.89%、1.65%、2.84%）；红外光谱和质谱分析结果表明磁性诱导所得晶体的结构组成没有变化。磁性诱导技术强化了薄荷脑结晶过程，有利于获得高品质的薄荷脑晶体。

This article aims to explore a new refined method for menthol extract (93.5%) with the aid of the external magnetic field. The influence of factors such as crystallization temperature, solution concentration, solvent type and intensity of magnetization on crystallization was also investigated. The crystallization conditions for L-menthol was optimized with the help of electromagnetic inducement, and the purity could reach 99.1% (GC-MS). Magnetic field greatly shortened the crystallization time and improved purity of crystals. Optical analyzer, differential thermal scanners, infrared spectrometer and gas chromatography-mass spectrometer were used to characterize the crystal of high purity. Optical analyzer analysis showed that the optical activity of the crystal was increased by 1.29%, 2.93% and 0.74% after magnetization treatment under different conditions. Differential thermal analysis showed that magnetic induction significantly shorten crystal melting process by 23.77%, 32.32% and 30.88% and improved the melting enthalphy by 0.89%, 1.65% and 2.84%. Infrared spectrometer and gas chromatography-mass spectrometer analysis showed that crystal structure remained unchanged. Magnetic induction could enhance crystallization progress of menthol and make it easier to obtain crystal of high quality.

安徽合芜蚌自主创新重大专项（2011AKKG1121）