Determination Of Amino Acids And Carbohydrates In Wine By Valve-switching Ion Chromatography Coupled Pulsed Amperometric Detector

As a kind of alcoholic drinks, wine has high nutritional value, the main contents including amino acids, carbohydrates, phenols, organic acids and various ions etc., especially for amino acids and carbohydrates, which are two important nutriments that playing significant role in absorbing nutrients and enhancing metabolism in human body. The components of essential amino acids in wine are very close to human body and are easy to be absorbed, can also form protein, increasing appetite, preventing alzheimer's disease and so on; and carbohydrates provide rich sweet taste experience, offering constitutive substance and energy for the metabolism of human body. From planting to production, the whole process, the changes of componentsof carbohydratesand amino acids have impact most on the quality of wine. Therefore, the quantitative analysis of amino acids and carbohydrates in the wine production process means a lot.The methods of detection of amino acids are mainly concludederivative spectrophotometric detection after cation exchange columncation and liquid chromatography column derivative spectrophotometric detection, the methodsof carbohydrates mainly contains liquid chromatography equipped with a differential detector, the derivativedeviation is large and process is complex, the precise quantification of low concentration matrix content is extremely unfavorable. In recent years, as important analytical method of amino acids and carbohydrates, ion exchange chromatography coupled with pulsed amperometric detector is gradually attractived, the application of valve switching technologyprovide effective measures for interference between amino acids and carbohydrates. The valve switching technology can switch between columns, trapping the target component, eliminate matrix interference, has good sensitivity, achieved good results in practical applications.This paper established an analytical method of determination of amino acids and carbohydrates by valve-switching anion exchange chromatography rapidly and simultaneously, the main research content are as follows:(1) A reverse solid phase extraction method was explored to remove pigment in wine, and successfully eluted target compounds of tryptophan.One SPE column(IC-RP) was chose for pigment removal in wine, and using 10% ethanol to elute the tryptophan which was trapped by SPE, the recovery of tryptophan reached 84% and the samples were lived up to the condition of detection of ion chromatography,reduced the impact of pigment in amino acid column PA10 and carbo pac PA10; meanwhile, the material, eleuent and dosage of extract liquor was optimised and getting a high effectively efficiency.(2) A valve-switching technology was set up to remove alcohol and detect amino acids and carbohydrates in wine simultaneously.One cation exchange column(CRC) was adopt to seperate amino acids and carbohydrates which were eluted sequentially according to the retention time of different materials, adjust the flow rate and concentration of eluent, the carbohydrates and amino acids realised effective separation on cation exchange column. Meanwhile, amino acids and carbohydrates were cut and detect on two different column respectively according to the principle of 10 port valve, avoided the coeluent on the same column and improved the efficiency of detection. One added valve was aimed to remove alcohol which has high signal disturbing the detection of carbohydrates. So, one injection valve, one 10 port valve and one 6 port valve were combined to reliease the removal of alcohol and detection of amino acids and carbohydrates simultaneously.(3) The valve-switching IC method was evaluated comprehensively. And it was successfully used for the alcohol removal and determination of carbohydrates and amino acids in six kinds of wine which come from different local.The mean correlation coefficient of calibration reached 0.99 on the range from 0.05 mg/L to 10 mg/L, and RSD for eight replicates of 0.50 mg/L standards mixture was 0.8-4.9%; The limits of detection of each substance ranged from 0.01 mg/L to 0.05mg/L. The accuracy of the method was confirmed by the average spiked recoveries ranged from 89.06-110.03%. The presented method was performed for the measurement of carbohydrates in wine. And the result was satisfactory.Linearity was achieved on the range from 0.05 mg/L to 10 mg/L with coefficients of determination( R2) greater than 0.99, which showed a good linear relationship. And RSD of each substance ranged from 0.8% to 4.9%. The limits of detection of each substance ranged from 0.01 mg/L to 0.05 mg/L. The average spiked recoveries ranged from 97.25-117.34%. The result was satisfactory.