玫瑰花青素测定中药中微量铁的应用研究

Application of anthocyanin from rose in determination of contents of ferrum

利用玫瑰花中花青素作为显色剂,建立玫瑰花青素-铁(Ⅲ)显色体系,采用紫外-可见分光光度法,测定了不同产地黄芪中铁的含量.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,pH在7.00~8.90玫瑰花青素能与铁(Ⅲ)形成稳定的络合物,最大吸收波长为640.0nm,摩尔吸收系数为2.03×103L·mol-1·cm-1,与玫瑰花青素最大吸收波长相差73.0nm,最佳显色时间为超声15min,放置10min,显色剂用量为16.0mL,测得河北安国、甘肃陇西、山西应县、山西浑源黄芪中铁的含量依次为83.13,81.24,55.55和54.79μg·g-1.Fe(Ⅲ)含量在4~24mg·L-1范围内与吸光度呈良好线性关系,线性相关系数R2=0.999 2,定量检出限为0.861mg·L-1,测定黄芪中微量铁的加样回收率为98.38%~101.5%,该方法可普遍用于植物中铁的含量测定.

A rose anthocyanin-iron(Ⅲ)colour system was established by using anthocyanin in rose as colour reagent.The content of iron in Astragalus membranaceus from different habitats was determined by ultraviolet-visible spectrophotometry.Methanol was used as anthocyanin extraction agent and the buffer solution of borax with pH of 9.18(25℃)was used to adjust the pH value.Rosocyanin can form a stable complex with iron(Ⅲ)in the pH range of 7.00 to 8.90.The maximum absorption wavelength and the molar absorption coefficient of complex is 640.0 nm and 2.03×103 L·mol-1·cm-1,which is 73.0 nm different from the maximum absorption wavelength of rosocyanin.The optimal color rendering time was 15 min of ultrasound and then 10 min of stasis,the dosage of developer is 16.0 mL.The content of iron in Astragalus membranaceus from Anguo(Hebei),Longxi(Gansu),Yingxian(Shanxi)and Hunyuan(Shanxi)is 83.13,81.24,55.55,and 54.79μg·g-1,respectively.There was a well linear relationship between absorbance and Fe(Ⅲ)with the contents in the range of 4 to 24 mg·L-1 and correlation coefficient of R2=0.999 2.A quantitative solution detection limit was 0.861 mg·L-1,and the recovery of trace iron in Astragalus membranaceus is 98.38%to 101.5%.This method can be widely used to determine the contents of Fe in plants.