Off-line elimination of carbohydrates for amino acid analysis of samples with high carbohydrate content by ion-exchange chromatography.
This paper introduces a new off-line sample preparation that eliminates carbohydrates from amino acid samples containing a high carbohydrate content before analysis by anion-exchange chromatography and integrated pulsed amperometric detection. First, the sample is introduced into a cation-exchange column in the hydrogen form. Carbohydrates are removed completely using 0.02% formic acid as a transfer fluid, while only amino acids are retained. Amino acids are then extracted from the cation-exchange resin by 10 ml of 1 M ammonia. The ammonia collected is evaporated to dryness and the residue redissolved in water containing 20 mg/l NaN3 for injection. All amino acids are recovered following the carbohydrate removal step. The average recovery is 97.2%. The relative standard deviation for seven replicates is less than 5.2%. The usefulness of the method is illustrated with chromatograms of ratafia samples obtained before and after the off-line removal of carbohydrates.
Ding
Yongsheng
Y
Research Center for Eco-Environmental Sciences, Chinese Academy Science, PO Box 2871, Beijing 100085, China.
Yu
Hong
H
Mou
Shifen
S
D000596:Amino Acids / Q000032:analysis*; D000641:Ammonia; D002241:Carbohydrates / Q000302:isolation & purification*; D002411:Cation Exchange Resins; D002852:Chromatography, Ion Exchange / Q000379:methods*; D005561:Formates; D006859:Hydrogen / Q000737:chemistry; D007202:Indicators and Reagents; D015203:Reproducibility of Results; D012972:Sodium Hydroxide
D000596:Amino Acids; D002241:Carbohydrates; D002411:Cation Exchange Resins; D005561:Formates; D007202:Indicators and Reagents; C030544:formic acid; D012972:Sodium Hydroxide; D000641:Ammonia; D006859:Hydrogen