Detection Of Harmful Elements And Aristolochic Acid A In Traditional Chinese Medicine By Capillary Electrophoresis-Capacitively Coupled Contactless Conductivity

High performance capillary electrophoresis（HPCE）is a liquid phase separation technology with capillary as the separation channel and high voltage direct current field as the driving force.It has become one of the most widely used green analytical technologies due to its advantages of high separation efficiency,fast analysis speed,small sample size required for analysis,and multiple separation modes in recent years.The capacitively coupled contactless conductivity detector（C⁴D）is a universal detector that can be used to detect charged ions,such as inorganic ions,organic ions,and biochemical substances.With the development of recent years,it has been successfully combined with capillary electrophoresis and high performance liquid chromatography and has received more and more attention.Tt has obvious advantages in the analysis of substances without UV-absorbing groups.The sample without derivation,can be directly detected,and the sensitivity is very high.Based on the advantages of rapid and efficient capillary electrophoresis and C⁴D with simple structure and easy operation,capillary electrophoresis capacitively coupled contactless conductivity detector method（CE-C⁴D）has shown broad application prospects in rapid separation and detection.The quality control of Chinese medicinal materials is the focus and difficulty of the development of Chinese medicinal materials industry.It is of great practical significance to realize the rapid detection of harmful substances in Chinese medicinal materials.In this work,based on the CE-C⁴D detection system built by our laboratory,the heavy metal ions in Chinese herbal medicines and related substances in Chinese herbal medicines are quickly separated and detected.This paper is mainly divided into the following four chapters:Chapter 1:We summarized the principle,characteristics and instrument optimization of capillary electrophoresis and capillary electrophoresis capacitively coupled contactless conductivity detector method.And the application of CE-C⁴D in the analysis of chemical drugs,traditional Chinese medicines and their preparations,and biopharmaceuticals also be summarized.At the same time,the importance of quality control of traditional Chinese medicine is briefly explained.Chapter 2:We established CE-C⁴D method to simultaneously measure 6 metal ions(Mn²⁺,Cd²⁺,Co²⁺,Pb²⁺,Ni²⁺,Cu²⁺)of the background electrolyte（BGE）withβ-alanine（β-Ala）（to maintain stable ionic strength）and lactic acid（Lac）（to provide background conductivity）.Through the systematic investigation and optimization of the concentration and composition of BGE,separation voltage,injection method and other separation conditions,the best separation conditions were obtained:the concentration of BGE is 30 mmol?L^-1β-alanine/lactic acid（p H 3.71）,separation voltage is 16 k V.Under these optimal conditions,all metal ions were successfully separated in less than 6min.These analytes showed a good linear relationship in the range of 5-1500μmol?L^-1,the correlation coefficient（R²）was 0.9910-0.9998,limits of detection（S/N=3）of 2.35-5.44μmol?L^-1,limits of quantification（S/N=10）of7.65-18.53μmol?L^-1.The relative standard deviations of migration time and peak area for six successive injections were 0.48%-0.72%and 3.44-8.77%,respectively.Only Cu²⁺was detected in the actual samples of Alostellum officinalis and Radix Codendrifolia,and the spiked recoveries were 94.0%-98.3%and 97.2%-101.1%,respectively.Other heavy metal ions were not detected.The experimental results showed that the method was fast,sensitive,reproducible and stable,and the operation process was simple,which laid a foundation for the subsequent application of this system in the analysis of heavy metal ions in Chinese medicinal materials.Chapter 3:On the basis of the previous work,the method based on electrochemical enrichment and CE-C⁴D was established for the separation and detection of six heavy metal ions in Chinese medicinal materials with the optimal conditions(separation voltage 16k V,BGE of 30 mmol?L^-1β-alanine/lactic acid,p H3.71).The electrochemical enrichment method was used for six metal ions(Mn²⁺,Cd²⁺,CO²⁺,Pb²⁺,Ni²⁺,Cu²⁺).The enrichment ratio is 2.57-12.95,and the limits of detection drops from 2.35-5.44μmol/L to 0.10-0.36μmol/L.This method provides a new idea and approach for the detection of trace harmful ions in drugs.Chapter 4:We established CE-C⁴D method for determination of aristolochic acid A in Chinese medicinal materials.Aristolochia acid is a kind of characteristic component in Aristolochia medicine,which has anti-tumor and increase the activity of phagocytes,but it has become a centrial issue at home and abroad because of its nephrotoxicity.This experiment will be through the optimization of separation conditions,under the optimal conditions（l0 mmol/L Tris-citric acid buffer solution（p H 8.50）as BGE,separation voltage of 20 k V）,the results showed that aristolochic acid A baseline separation,the experimental results show that aristolochic acid A in0.02～0.33 mg/m L good linear relationship,the correlation coefficient（R²）=0.9989,the relative standard deviation（n=6）was 2.8%.The recoveries were 92.40%-115.87%,which can realize the separation and detection of aristolochic acid and be used for the determination of the content of aristolochic acid in actual medicinal materials,providing a method for the quality control of aristolochic acid and other Chinese medicinal materials.