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Shimadzu Review 81[3・4] (2024)
Abstract
A complementary HPLC method for the determination of 37 proteinogenic D/L-amino acids, excluding proline, was previously reported. This method involves analyzing each sample twice while automatically switching between two separation methods for the o-phthalaldehyde (OPA)-derivatized fluorescent diastereomers of D/L-amino acids formed by independently using two chiral thiols, N-acetyl-l-cysteine (NAC) and N-isobutyryl-l-cysteine (NIBC). In this study, separation of OPA/NIBC-derivatized diastereomers with higher hydrophobicity under a single analytical method was investigated. Increasing the methanol ratio in the mobile phase and setting the column temperature to 20 ℃ enabled the simultaneous separation of the 37 diastereomers of D/L-amino acids within 66 minutes. The peak area repeatability for each diastereomer was 1.6% RSD or less because of automating the OPA/NIBC derivatization of D/L-amino acids. The calibration curve linearity was 0.999 or greater for each diastereomer. Applying this method to liquor samples revealed that the overall ratio of d-amino acid to D/L-amino acid was 6% or less, but determination was possible. Principal component analysis of the five liquor samples showed that these samples were classified by type of liquor. The established method has the potential to be applied to liquor profiling.
Solutions Center of Excellence, Analytical & Measuring Instruments Division, Shimadzu Corporation, Kyoto, Japan
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