Thermospray liquid chromatography/mass spectrometry study of diastereomeric isoindole derivatives of amino acids and amino acid amides

• Published in: Journal of pharmaceutical and biomedical analysis Vol. 13; no. 12; pp. 1459 - 1464
• Main Authors: van Leuken, R.G.J., Duchateau, A.L.L., Kwakkenbos, G.T.C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-11-1995; Elsevier Science
• Subjects: Acetylcysteine; Amino acid amides; Amino acids; Amino Acids - analysis; Antibacterial agents; Antibiotics. Antiinfectious agents. Antiparasitic agents; Biological and medical sciences; Chromatography, High Pressure Liquid; Chromatography, Liquid; Enantiomeric excess determination; Fragmentation mechanism; Gas Chromatography-Mass Spectrometry; Hydrolysis; Indicators and Reagents; Indoles - analysis; Isoindole derivatives; Medical sciences; o-Phthalaldehyde; Pharmacology. Drug treatments; Spectrophotometry, Ultraviolet; Stereoisomerism; Temperature; TSP-LC/MS; Fragmentation mechanism; Amino acids; TSP-LC/MS; Enantiomeric excess determination; Isoindole derivatives; Amino acid amides; Aminoacid; Analytical method; Enantiomeric excess; Organic amide; Thermospray; Indole derivatives; Mass spectrometry; Diastereomer; Liquid liquid chromatography; Fragmentation
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/0731-7085(95)01580-9

A thermospray liquid chromatography/mass spectrometry (TSP-LC/MS) method is described for determination of the enantiomeric excess of α-amino acids and α-amino acid amides as their
o-
phthalaldehyde/N-
acetyl-
l-cysteine
(OPA/NAC) derivatives.
The source temperature is an important factor in optimizing the sensitivity of the TSP-LC/MS analysis, whereas the repeller voltage is of minor importance. On-column mass spectra were acquired for the OPA/NAC derivatives of several α-amino acids and α-amino acid amides. For the main fragment ions, mass spectra fragmentation pathways are proposed. The applicability of the method is demonstrated by means of the enantiomeric excess determination of valine in a sample from an enzymatic hydrolysis experiment.
Using single ion monitoring, the detection limit of
d-valine in the presence of excess
l-valine is 10 pmol. The present TSP-LC/MS method is useful for validating the results obtained from LC/UV or LC/fluorescence methods for the enantiomeric excess determination of α-amino acids and α-amino acid amides.