Supercritical carbon dioxide extraction of Mentha pulegium L. essential oil

The dependence of Mentha pulegium L. (pennyroyal) essential oil composition, obtained by supercritical carbon dioxide (SC-CO₂), with the following parameters: pressure, temperature, extraction time (dynamic), and modifier (methanol) was studied. The results were also compared with those obtained by conventional hydrodistillation method in laboratory conditions. Regarding the percentages of menthone (30.3%) and pulegone (52.0%), the optimum SFE results were obtained at the following experimental conditions: pressure=100 atm, T=35 °C, dynamic time=10 min, and V_modifier=0 μl. The results of hydrodistillation showed that the major components of M. pulegium L. were pulegone (37.8%), menthone (20.3%), and piperitenone (6.8%). The evaluation of the composition of each extract was performed by gas chromatography-mass spectrometry.     

用GC-MS法分析春、秋季薄荷油成分

用毛细管气相色谱－质变法对同一种薄荷春季、秋季茎叶中挥发油的精细成分进行了分析测试,分离出春季薄荷油中20个组分、秋季薄荷油中16个组分,通过计算机库存质谱图和标准谱图册检索鉴定出各个组分对应的化合物,用峰面积归一化方法计算出各组分的相对含量,其中春季薄荷以（cis)－薄荷酮(3.70%）、（2R－cis）－薄荷酮（1.25%）、（1α,2α,5β）－薄荷醇（16.88％）、（1α,2β,5β）－薄荷醇(74.98%)为主,秋季薄荷以(cis)-薄荷酮(3.88%)、(2R-cis)-薄荷酮(1.24%)、（1α,2α,5β）－薄荷醇(15.76%)、（1α,2α,5β）－薄荷醇(69.97%)、α-蒎烯(2.68%)、β－蒎烯(2.07%)和拧檬烯(1.71%)为主。     

Supercritical fluid extraction—Achiral liquid chromatography with circular dichroism detection for the determination of menthone enantiomers in natural peppermint oil samples

A simple and enantioselective method for the determination of menthone enantiomers in peppermint essential oil samples is proposed. The method involves the initial supercritical fluid extraction (SFE) to clean-up and extraction of analytes and their preconcentration on C₁₈ adsorption cartridges followed by achiral liquid chromatographic separation and direct circular dichroism (CD) detection. The calibration curve of the anisotropy factor (g) versus the enantiomeric excess was linear, with a correlation coefficient (R²) of 0.9970. The precision evaluated by UV peak area and CD peak area was suitable both in terms of intra- and inter-day precision (RSD < 5.1% in all cases). The usefulness of the proposed method was demonstrated by analyzing natural and spiked peppermint oil samples. This method has the advantages of being rapid and precise without using an expensive chiral column. It was demonstrated to be suitable for the simultaneous determination of both enantiomers and for assessing the chemical purity of menthone.