Indirect Chiral HPLC Determination and Fluorimetric Detection of d-Amino Acids in Milk and Oyster Samples

• Published in: Journal of dairy science Vol. 89; no. 1; pp. 82 - 89
• Main Authors: Rubio-Barroso, S, Santos-Delgado, M. J, Martin-Olivar, C, Polo-Diez, L. M
• Format: Journal Article
• Language: English
• Published: Savoy, IL Elsevier Inc 01.01.2006; Am Dairy Sci Assoc; American Dairy Science Association
• Subjects: Acetylcysteine - chemistry; amino acids; Amino Acids - analysis; analytical methods; Animal productions; Animals; Biological and medical sciences; Centrifugation; Chromatography, High Pressure Liquid - methods; d-amino acid; derivatization reaction; enantiomers; fluorimetric detection; food analysis; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; HPLC; Indicators and Reagents; Methods of analysis, processing and quality control, regulation, standards; Milk - chemistry; o-Phthalaldehyde - chemistry; Ostreidae - chemistry; oysters; sampling; seafoods; Spectrometry, Fluorescence; Stereoisomerism; Terrestrial animal productions; Vertebrates; d-amino acid; derivatization reaction; HPLC; fluorimetric detection; Sample; Dairy product; HPLC chromatography; Derivatization; Analysis method; D-amino acid; Dairy industry; Control method; Detection; Milk
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(06)72071-9

The indirect chiral method, based on the o-phthaldialdehyde reaction using the chiral N-acetyl-l-cysteine reagent, has been optimized to determine d-amino acids in milk and oyster samples. Both the derivatization reaction and the HPLC separation have been improved, and simple sample treatments were proposed. The milk sample preparation involved centrifugation and filtration through polytetrafluoroethylene filters for determination of free d-AA. Two methods, nonenzymatic and enzymatic, were applied to determination of free and total d-AA, respectively, in oyster samples. The d-AA contents were in the range of 0.14 to 4.32mg/L for milk samples and 0.80 to 15.9mg/g for oyster samples, with relative standard deviations lower than 10% (n=4), except for d-Tyr. In general, mean recoveries were greater than 90% with relative standard deviations lower than 9% (n=4) at concentration levels from 0.055 to 0.426mg/L for milk samples and 0.348 to 1.10mg/ g for oyster samples.