邻甲酚酞褪色分光光度法定量测定γ-环糊精含量

Quantitative Determination of γ-Cyclodextrin with o-Cresolphalein Fading Spectrophotometry

以邻甲酚酞(OCP)为探剂,首次建立了基于邻甲酚酞褪色反应的γ-环糊精含量分光光度测定方法。其原理是在碱性条件下,γ-环糊精(γ-CD)包络OCP分子使其发生褪色反应,并且其褪色程度△A与γ-CD浓度在一定范围内呈线性关系,符合朗伯比尔定律。研究了显色条件对γ-CD含量测定的影响。结果表明:当在30℃下显色15 min,加入OCP浓度为0.21 mmol/L,缓冲液pH=9.51时,γ-CD在0~15mmol/L范围内线性关系良好。回归方程为ΔA=0.032 5Cγ-CD(mmol/L),相关系数R2=0.997 5,检出限为0.066 mmol/L,表观摩尔吸光系数ε=3.06×10~3L·mol^(-1)·cm^(-1),灵敏度较高。样品平均实测回收率在99.1~101.5%之间,测定结果 RSD为1.47%(n=10)。该光度测定方法的准确度与HPLC法接近,且具有良好的稳定性与重现性,同时操作简便,测定快速,较HPLC法更易于推广普及。

A new spectrophotometric determination method of γ-Cyclodextrin content based on o-cresolphalein（ OCP） fading reaction was established,using OCP as a probe. Its theory was that under alkaline condition,theγ-cyclodextrin reacted with OCP molecule to form an inclusion complex. The concentration of γ-CD was linear proportional to the degree of fading △A within a certain concentration range,which in accordance with lambert-beer’s law. The influence of chromogenic conditions on determination of γ-CD content was researched,and the results showed that there was a good linear relationship with γ-CD in the concentration from 0 to 15 mmol/L under the condition that the OCP concentration was 0. 21 mmol/L,buffer solution p H = 9. 51,proceeding at 30 ℃ for 15 min. The regression equation was ΔA = 0. 032 5 Cγ-CD（ mmol/L）,correlation coefficient R2= 0. 997 5,apparent molar absorption coefficient ε = 3. 06 × 103 L·mol-1·cm-1,and the detection limit was 0. 066 mmol/L,which had relatively high sensitivity. The average measured recovery rate of samples was 99. 1% 101. 5%,and the determined RSD was 1. 47%（ n = 10）. This spectrophotometric determination method had accuracy close to HPLC method,and good stability and reproducibility,as well as the straightforward operation and the quick determination,which was easier for promotion and popularization compared with HPLC method.