A new procedure for determining DL amino acid ratios in fossils using reverse phase liquid chromatography
A new procedure for determining DL amino acid ratios in fossils using reverse phase liquid chromatography
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DOI：
10.1016/s0277-3791(97)00086-3
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发表时间：
1998-01-01
影响因子：
4
通讯作者：
Manley, WF
中科院分区：
文献类型：
--
作者：
Kaufman, DS;Manley, WF
氨基酸地质年代学主要基于化石中消旋化的程度，如通过D-和L-异构体的比例量来测量。在这里，我们报告了一个新的，全自动反相高效液相色谱法简单，精确的立体异构体分离程序。使用市售试剂和设备在75分钟内以基线分辨率分离至少9对ar-氨基酸。通过优化柱前衍生，我们获得了化合物的检测能力在亚皮摩尔范围内，足够毫克大小的软体动物样品。四个化石的九个Dr比率的分析重现性平均为7%（n = 14-28），跨越广泛的年龄范围。Asp和Glu Dr比值的分离度和重现性最一致，分析变异分别为2%和3%。在三个化石软体动物样品中的比率分析的新方法和先前测量的GC为基础的实验室重叠在17个18例，当考虑到FL SD分析误差和+/-1 SD实验室间的变化。为了确定最大限度地减少诱导外消旋化同时最大限度地提高氨基酸回收率的水解程序，在110 ℃下水解了7种不同年龄和属的粉末状软体动物化石0-48 h。大多数氨基酸的浓度在6-8小时后达到稳定平台。对于年轻的样品，其中更快的外消旋氨基酸为目标（特别是天冬氨酸），6小时的水解时间最大限度地减少诱导外消旋，同时实现几乎完全的氨基酸回收。对于较旧的样品，优选在110 ℃下22小时。(C)1998爱思唯尔科技有限公司版权所有。
Amino acid geochronology is based largely on the extent of racemization in fossils, as measured by the ratio amounts of D- and L-isomers. Here we report a new, fully automated reverse phase HPLC procedure for simple and precise stereoisomeric separations. At least nine pairs of ar-amino acids are separated with baseline resolution in 75 min using commercially available reagents and equipment. By optimizing precolumn derivatization, we attained compound detectability in the sub-picomole range, sufficient for milligram-size molluscan samples. Analytical reproducibility for nine Dr ratios in four fossils spanning a broad range of ages averages 7% (n = 14-28). Asp and Glu Dr ratios are the most consistently well resolved and reproduced, with analytical variations of 2 and 3%, respectively. Ratios in three fossil mollusc samples analyzed by the new method and measured previously by GC-based laboratories overlap in 17 out of 18 cases, when considering the fl sd analytical errors and +/-1 sd inter-laboratory variation. To determine the hydrolysis procedure that minimizes induced racemization while maximizing amino acid recovery, nle hydrolyzed seven powdered molluscan fossils of different ages and genera for 0-48 h at 110 degrees C. Concentrations of most amino acids reached a stable plateau after 6-8 h. For young samples, in which faster-racemizing amino acids are targeted (especially Asp), a hydrolysis time of 6 h minimizes induced racemization while attaining nearly complete amino acid recovery. For older samples, 22 h at 110 degrees C is preferred. (C) 1998 Elsevier Science Ltd. All rights reserved.