紫甘蓝花青素—铁(Ⅲ)显色体系测定中药中铁的含量

Content Determination of Ferrum in Chinese Herbal Medicine by the Color Rendering System of Fe (Ⅲ) and Anthocyanin in Red Cabbage Extract

优化紫甘蓝花青素—铁(Ⅲ)显色体系,利用该体系首次测定中草药中铁的含量。根据在pH 7. 2~8. 7中紫甘蓝花青素能与铁(Ⅲ)形成稳定的配合物,该配合物最大吸收波长为632. 0 nm,与紫甘蓝花青素的最大吸收波长相差79. 0nm,采用甲醇作为花青素提取剂,以pH 9. 18(25℃)的硼砂pH缓冲剂调节pH值,利用紫外-可见分光光度法,测定了不同产地黄芪和款冬花中铁的含量。该显色体系最佳显色时间为30 min,显色剂用量为10. 0 mL,测得河北安国、甘肃陇西、山西应县、山西浑源黄芪及贵州大龙款冬花中铁的含量依次为83. 7、81. 6、55. 5、54. 9、165. 5μg/g。该方法 Fe(Ⅲ)含量在2~10μg/mL范围内与吸光度呈良好线性关系,线性相关系数R2=0. 999 1,加样回收率为99. 91%~102. 4%,可普遍用于植物中铁的含量测定。

Optimizing the color rendering system of Fe(Ⅲ)and anthocyanin in red cabbage extract was used to determine the contents of ferrum in Chinese herbal medicine for the first time.Anthocyanin which extracted from the red cabbage could form a stable complex with Fe(Ⅲ)in pH 7.2~8.7,the maximum absorption wavelength of the complex was 632.0 nm and there is a difference of 79.0 nm from the maximum absorption wavelength of anthocyanin.Methanol was used as anthocyanin extraction agent,the buffer solution of borax with pH of 9.18(25℃)was used to adjust the pH value and the content of Fe in Chinese herbal medicine was determined using this color rendering system by UV spectrophotometry.The optimal color rendering time was 30 min of stasis,the dosage of developer is 10.0 mL.By measuring,the content of Fe in Astragalus membranaceus which was from Anguo Hebei,Longxi Gansu,Yingxian Shanxi,Hunyuan Shanxi and in Tussilago farfara which is from Dalong Guizhou was 83.7,81.6,55.5,54.9,165.5μg/g,respectively.There was a well linear relationship between absorbance and Fe(Ⅲ)of which contents was in the range of 2~10μg/mL,correlation coefficient R2=0.999 1,the optimum recoveries of 99.91%~102.4%by addition of the standard solution of Fe in Chinese herbal medicine was obtained.This method is used in the determination of Fe in plants commonly.