PMID- 4073503
OWN - NLM
STAT- MEDLINE
DCOM- 19860108
LR  - 20190628
IS  - 0003-2697 (Print)
IS  - 0003-2697 (Linking)
VI  - 149
IP  - 2
DP  - 1985 Sep
TI  - Analysis of problems encountered in the determination of amino acid enantiomeric 
      ratios by gas chromatography.
PG  - 484-91
AB  - A previously described procedure for determining the enantiomeric ratios of amino 
      acids has produced inconsistent results when determining relatively low (less 
      than or equal to 0.110) D/L ratios. The method involves synthesis of 
      diastereomeric N-trifluoroacetyl-L-prolyl-D/L-amino acid ester dipeptides which 
      are resolved by gas chromatography (GC). We have found that triethylamine, which 
      is added to maintain a basic pH during the coupling reaction, racemizes the 
      chiral reagent N-trifluoroacetyl-L-prolyl chloride (TPC). Coupling of partially 
      racemized TPC to D/L-amino acid esters results in the formation of four 
      dipeptides (two pairs of enantiomers) instead of the expected two diastereomeric 
      dipeptides. The enantiomeric dipeptides coelute on an achiral GC column, 
      resulting in erroneous D/L ratios. More accurate D/L ratios are obtained by 
      preparing the volatile N-trifluoroacetyl-D/L-amino acid isopropyl ester 
      derivative which can be separated into its enantiomers on a chiral GC column such 
      as the Chirasil-Val III (registered trademark of Applied Science Laboratories).
FAU - Payan, I L
AU  - Payan IL
FAU - Cadilla-Perezrios, R
AU  - Cadilla-Perezrios R
FAU - Fisher, G H
AU  - Fisher GH
FAU - Man, E H
AU  - Man EH
LA  - eng
GR  - AG04545/AG/NIA NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Anal Biochem
JT  - Analytical biochemistry
JID - 0370535
RN  - 0 (Amino Acids)
RN  - 0 (Ethylamines)
RN  - 36724-68-2 (N-trifluoroacetylprolyl chloride)
RN  - 9DLQ4CIU6V (Proline)
RN  - VOU728O6AY (triethylamine)
SB  - IM
MH  - Amino Acids/*analysis
MH  - Brain Chemistry
MH  - Chromatography, Gas
MH  - Ethylamines
MH  - Humans
MH  - Proline/analogs & derivatives
MH  - Stereoisomerism
EDAT- 1985/09/01 00:00
MHDA- 1985/09/01 00:01
CRDT- 1985/09/01 00:00
PHST- 1985/09/01 00:00 [pubmed]
PHST- 1985/09/01 00:01 [medline]
PHST- 1985/09/01 00:00 [entrez]
AID - 0003-2697(85)90603-7 [pii]
AID - 10.1016/0003-2697(85)90603-7 [doi]
PST - ppublish
SO  - Anal Biochem. 1985 Sep;149(2):484-91. doi: 10.1016/0003-2697(85)90603-7.