手性HPLC法测定布洛芬立体选择性酯化的转化率和对映体过量

以脂肪酶在正己烷中催化消旋布洛芬与正丁醇的立体选择性酯化反应为例，研究了用手性ＨＰＬＣ法进行分析时产物及底物的峰面积变化与转化率的关系，确定了布洛芬丁酯与未反应布洛芬的峰面积－浓度响应因子的比值，从而可通过一次进样用峰面积直接测定布洛芬的转化率和对映体过量。

Chiral HPLC Determination of Conversion and Enantiomeric Excess of Enzyme Catalyzed Stereoselective Esterification of Racemic Ibuprofen

In the study of enzyme catalyzed kinetic resolution of racemates, it is imperative to assay how the optical yield varies with chemical conversion. In this paper, a method using one-time injection to determine enantiomeric excess and conversion of the stereoselective esterification of racemic ibuprofen with n-butanol catalyzed by lipase was developed with a commercially available HPLC CSP column Regis(S, S) Whelk-01. In the linear range of detector, all peak areas of products and substrates are proportional to their concentrations. Because the total mole concentration remains unchanged (equal to the initial value of ibuprofen) in the reaction process, the conversion could be calculated from the peak areas, provided the ratio of response factors was known. The calibration curves of two ibuprofen enantiomers with racemic ibuprofen as external standard were overlapped, indicating fiR = fiS. By investigating the variation of peak areas of products and substrates against conversion (determined by external standard), the ratio of peak area-concentration response factor of ibuprofen butyl ester to that of unreacted ibuprofen was determined to be 1 through linear regressions, from which the conversion could be directly determined by the self normalization of the peak areas. With a mobile phase of IPA/hexane/HAc/triethylamine (15/85/0.2/0.05, V/V, flow rate 0.4 mL/min), the resolution of ibuprofen enantiomers was sufficient for precise enantiomeric purity determination.