Study On The Quality Evaluation Of Colla Corii Asini Based On Low-field Nuclear Magnetic Resonance Technology

Objective: Using low-field nuclear magnetic resonance technology(LF-NMR)for rapid detection of different brands of adulterated colla corii asini(Chinese name E'jiao),and combined with the stoichiometric treatment of data in order to evaluate the quality of donkey-hide gelatin,and establish a scientific,complete and fast quality test method for E'jiao.Methods:(1)Low-field NMR technique combined with principal component analysis was used for rapid detection and analysis of different brands and different batches of donkey-hide gelatin.(2)Using three different brands of E'jiao for adulteration experiments,and rapid detection by LF-NMR technology,combined with principal component analysis(PCA)and step-by-step discriminant analysis(Step-LDA)to process the test data to find feasible analysis method.(3)The research uses low-field NMR technology to explore the detection limit of common adulterants in different brands of adulterated E'jiao.(4)The hydrolysis conditions of E'jiao were optimized,and the ELSD-HPLC method was used to compare and analyze the four main amino acids in different batches of E'jiao,non-adjuvanted E'jiao juice,and oxhide gelatine.Results:(1)Using LF-NMR technology combined with the main component method(PCA)to reflect the difference in quality characteristics of seven different brands of E'jiao,so as to achieve differentiation and identification of different brands of E'jiao.On this basis,using LF-NMR technology to inspect the quality difference of E'jiao in different batches of E'jiao companies in in Dong'e,Fujiao,and Hongjitang.The results show that the quality of E'jiao in different batches has little difference,indicating that the quality of the brand E'jiao products is relatively stable.(2)The combination of LF-NMR and PCA can effectively reflect the differences in quality characteristics of three brands of pure E'jiao and different forms of adulterated E'jiao,so as to realize the identification of adulterated E'jiao and pure E'jiao while different adulteration ratios adulterated E'jiao can also get the basic distinction;Using Step-LDA to build the discriminant model of pure E'jiao and different forms of adulterated E'jiao discrimination is more significant,similar data sets,the distinction between classes is more obvious.Different proportions of adulterated E'jiao were regularly distributed on the score chart with no overlap.The cross-validation results show that Step-LDA discriminant model is better than others,which can not only achieve the purpose of rapid detection of adulterated E'jiao but also characterize the influence of different adulteration ratios on the quality of E'jiao.(3)LF-NMR combined with PCA showed that the detection limit of each adulterant substance in three different brands of Ejiao as follows: Fujiao: oxhide gelatin 9%~13%,procine gelatin 7%~11%,miscellaneous gelatin 5%~9%;Dong'e Ejiao: oxhide gelatin 5% ~9%,procine gelatin 13%~15%,miscellaneous gelatin 5%~7%;Hongjitang Ejiao: oxhide gelatin 7%~11%,procine gelatin 11%~13%,miscellaneous gelatin 5%~9%;The Step-LDA score model was established to determine the detection limits of adulterant in E'jiao.The detection limits are as follows: Fujiao: oxhide gelatin 7%~11%,procine gelatin 9%~13%,miscellaneous gelatin 3%~5%;Dong'e Ejiao: oxhide gelatin 5%~9%,procine gelatin 9%~13%,miscellaneous gelatin 3%~5%;Hongjitang Ejiao: oxhide gelatin 7%~9%,procine gelatin 7%~9%,miscellaneous gelatin 5%~7%.(4)The HPLC-ELSD method was used to analyze and determine the contents of the 4 main underivatized amino acids.The results showed that the contents of L-glycine,L-hydroxyproline,L-alanine and L-proline in the 9 batches of E'jiao were 20.58%~23.82%,9.55%~11.60%,8.05%~9.35% and 11.12%~13.55%.The content of L-glycine in 9 batches of E'jiao juice was 26.25%~28.23%,and L-hydroxyproline was 12.93%~13.31%,L-alanine was 11.38%~11.05%,L-proline was 15.86%~16.21%,L-glycine content in 10 batches of oxhide gelatin ranged from 24.03%~26.31%,L-hydroxyoxime ranged from 11.86%~13.15%,L-alanine from 9.08% to 10.58%,and L-proline from 14.06% to 16.10%.The results showed that the contents of the four main amino acids in the three kinds of gelatin all reached the standard stipulated in the Chinese Pharmacopoeia(Ministry of Public Health of the People's Republic of China,2015),and the content of gelatin juice was the highest,the content of gelatin was the second,the content of gelatin was the lowest,which could be used as intrinsic quality index to distinguish different gums class.Conclusions: Low-field nuclear magnetic technology was used to identify and evaluate the quality of Chinese medicine of E'jiao.This method can ensure rapid and accurate NMR analysis of animal glue samples in order to understand the quality of animal glue samples,so as to quickly and accurately identify inferior glue and provide quality assurance for people's consumption;The HPLC-ELSD method was used for the first time to determined the contents of the four main amino acids in the unadjuvanted E'jiao juice and determined the minimum standard for amino acid content.The E'jiao juice removes the interference of the excipients on the determination of the amino acid content after hydrolysis.The result is more accurate and efficient,and the quality control of E'jiao is performed from the source.