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首页> 外文期刊>Chirality: The pharmacological, biological, and chemical consequences of molecular asymmetry >Evaluation of enantioselective gas chromatography for the determination of minute deviations from racemic composition of alpha-amino acids with emphasis on tyrosine: Accuracy and precision of the method
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Evaluation of enantioselective gas chromatography for the determination of minute deviations from racemic composition of alpha-amino acids with emphasis on tyrosine: Accuracy and precision of the method

机译：评价对映选择性气相色谱法，以测定酪氨酸为重点的α-氨基酸外消旋组成的微小偏差：方法的准确性和精密度

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摘要

Whereas the determination of high enantiomeric fractions (EF) of chiral compounds is very well established, the accurate determination of small deviations from racemic compositions has not yet received much attention despite its relevance to studies dealing with the origin of homochirality, where only small initial enantiomeric bias is expected. Racemic samples of representative alpha-amino acids were derivatized as N-(O,S)-trifluoroacetyl/ethylesters and analyzed by enantioselective gas chromatography (GC) on fused silica capillaries coated with the chiral stationary phases (CSPs) ChiraSil-D-Val, Chirasil-L-Val, and Lipodex E with GC/FID and GC/MS detection. The validation (accuracy and precision) of the determination of the enantiomeric fraction EF of the D-enantiomer in racemic or near-racemic compositions for 10 DL-alpha-amino acids obtained from commercial sources has been carried out. Emphasis is given to DL-tyrosine, the enantiomers of which have recently been claimed to show different crystallization properties. Values of EF obtained from GC measurements using CSPs were compared with those from CE using chiral mobile phase additives. While the precision of the GC method is generally better than 0.08% for all DL-alpha-amino acids studied, accuracy (trueness) of determination of amino acids with polar side chains is poorer than expected from the precision as a result of systematic errors. The accuracy determined relied on measurements on two oppositely configurated CSPs.
机译：尽管对手性化合物的高对映体分数（EF）的测定已得到很好的确定，但尽管它与处理同质手性起源的研究相关，而对消旋组成的小偏差的准确测定仍未引起足够的重视，在该研究中，手性仅是小的对映体偏见是预期的。将代表性的α-氨基酸的外消旋体样品衍生为N-（O，S）-三氟乙酰基/乙基酯，并通过对映选择性气相色谱（GC）在涂覆有手性固定相（CSP）ChiraSil-D-Val的熔融石英毛细管上进行分析具有GC / FID和GC / MS检测功能的Chirasil-L-Val和LipodexE。已对从商业来源获得的10种DL-α-氨基酸的外消旋或近外消旋组合物中D-对映体的对映体级分EF的测定进行了验证（准确性和精确度）。重点是DL-酪氨酸，最近已宣称其对映异构体显示出不同的结晶特性。将使用CSP进行GC测量获得的EF值与使用手性流动相添加剂获得的CE的EF值进行比较。尽管对于所有研究的DL-α-氨基酸，GC方法的精度通常都优于0.08％，但由于系统误差，测定带有极性侧链的氨基酸的准确性（真实性）比从精度中预期的要差。确定的精度取决于对两个相反配置的CSP的测量。

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