- 學位論文
衍生化液相層析螢光法對(+)-Menthol與(-)-Menthol之鏡像分析
Enantiomeric Analysis of (+)-Menthol and (-)-Menthol by Fluorimetric Derivatization and High-Pressure Liquid Chromatography
摘要
本研究利用螢光偵測導向之衍生反應，加上高壓液相層析法(HPLC)，對互為鏡像異構物之(+)-menthol與(-)-menthol，建立一個簡單靈敏之分析方法。本法利用(+)-2-(6-methoxyl-2-naphthyl) propionyl chloride (MNP-COCl)為衍生試劑，以甲苯為反應溶媒，將(+)-menthol與(-)-menthol加以衍生成螢光性之衍生物，以α-naphthyl caprate為內部標準品，利用C-8為固定相及甲醇：水：四氫呋喃(80：18：2, v/v)為移動相進行分離，對所得之衍生物以螢光偵測器(激發波長235nm；放射波長350nm)加以偵測。所建立之分析方法定量範圍為5~50μM，偵測極限為1μM ( S / N = 3；檢品注入體積為10μL)。 本研究對影響(+)-menthol與(-)-menthol衍生反應之重要因素，包括反應溶媒、衍生試劑需要量、鹼性催化劑、反應時間及溫度等，皆詳加探討。 本法並應用於瑞士薄荷(Mentha piperita ‘Swiss’)及巧克力薄荷(Mentha x piperita ’Chocolate’)二種薄荷草中(-)-menthol之分析；本法步驟簡單，利用甲苯萃取薄荷草中(-)-menthol，所得甲苯萃取液逕加衍生，所得(-)-menthol之衍生物，進行HPLC-螢光分析。
並列摘要
Analytical derivatization coupled with high-pressure liquid chromatography (HPLC) was used for the analysis of (+)-menthol and (-)-menthol. The method was based on the derivatization of (+)-menthol and (-)-menthol with a fluorescent derivatizing reagent, (+)-2-(6- methoxyl-2-naphthyl) propionyl chloride (MNP-COCl) in toluene. The resulting derivatives were separated on a C-8 column, using a mixed solvent of methanol : water : tetrahydrofuran (80:18:2, v/v) as the mobile phase. The separated (+)-menthol and (-)-menthol derivatives were monitored with a fluorimetric detector (excitation 235 nm and emission 350nm). α-Naphthyl caprate was used as an internal standard (I.S.), and the peak area ratios of (+)-menthol and (-)-menthol derivatives to I.S. were used for quantitative analysis. The linear range of the method for the determination of (+)-menthol and (-)-menthol was 5~50μM. The detection limit (signal to noise ratio = 3, injected volume 10μL) of (+)-menthol and (-)-menthol was about 1μM. Several parameters affecting the derivatization of (+)-menthol and (-)-menthol were discussed including reaction solvent, amount of derivatizing reagent, base catalyst, reaction temperature and time. Application of the method to the analysis of (-)-menthol in mint plants was studied. After toluene extraction of (-)-menthol from mint plants, the toluene extract was directly derivatized with MNP-COCl for HPLC-fluorescence detection.