ISSN:
1076-5174
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
A simple procedure for the extraction and derivatization of α-amino acids and α-keto acids from human plasma is described. This stable isotope dilution method permits the quantification of isotopic enrichment and concentrations of several α-keto and α-amino acids simultaneously. The derivatization process results in methylformated, pentafluorobenzylated α-amino acids and pentafluorobenzylated α-keto acids. The derivatives proved to be very stable when stored at 5°C. Under electron capture chemical ionization (ECCI) conditions the derivatized amino acid produces abundant [M - PFB]- or [M - PFB - CH3OH]- anions; the α-keto acid gives abundant [M - PFB]- anions. The method was applied to the analyses of 100 μl plasma samples in studies on protein metabolism. For the determination of concentrations [α-ketoisocaproic acid (α-KIC), Leu, Phe and Tyr] and enrichments ([1-13C]-α-KIC, [1-13C]-Leu, D5-Phe, D2-Tyr, D4-Tyr), resulting from administered tracers, the corresponding [M - PFB]- or [M - PFB - CH3OH]- anions were monitored. Higher labelled analogues were used as internal standards. The overall sensitivity was sufficient to study isotopic enrichments in the range 0.2-10 at.% excess.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jms.1190300908
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