Effects of the pH and Concentration on the Stability of Standard Solutions of Proteinogenic Amino Acid Mixtures

• Published in: Analytical Sciences Vol. 33; no. 11; pp. 1241 - 1245
• Main Authors: KATO, Megumi, YAMAZAKI, Taichi, KATO, Hisashi, YAMANAKA, Noriko, TAKATSU, Akiko, IHARA, Toshihide
• Format: Journal Article
• Language: English
• Published: Singapore The Japan Society for Analytical Chemistry 2017; Springer Nature Singapore; Japan Science and Technology Agency
• Subjects: Accelerated tests; Amino acid mixed standard solution; Amino acids; Analytical Chemistry; certified reference material; Chemistry; Degradation; Glutamic acid; pH effects; preparation; Pyroglutamic acid; Stability; Stability analysis; glutamic acid; Amino acid mixed standard solution; certified reference material; stability; preparation
• ISSN: 0910-6340; 1348-2246
• DOI: 10.2116/analsci.33.1241

To prepare metrologically traceable amino acid mixed standard solutions, it is necessary to determine the stability of each amino acid present in the mixed solutions. In the present study, we prepared amino acid mixed solutions using certified reference standards of 17 proteinogenic amino acids, and examined the stability of each of these amino acids in 0.1 N HCl. We found that the concentration of glutamic acid decreased significantly during storage. LC/MS analysis indicated that the instability of glutamic acid was due to the partial degradation of glutamic acid to pyroglutamic acid in 0.1 N HCl. Using accelerated degradation tests, we investigated several solvent compositions to improve the stability of glutamic acid in amino acid mixed solution, and determined that the change of the pH by diluting the mixed solution improved the stability of glutamic acid.