A new procedure for determining DL amino acid ratios in fossils using reverse phase liquid chromatography

Darrell S Kaufman, William F. Manley

Research output: Contribution to journalArticle

225 Citations (Scopus)

Abstract

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 sample and precise stereoisomeric separations. At least nine pairs of DL-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 DL ratios in four fossils spanning a broad range of ages averages 7% (n = 14-28) Asp and Glu DL 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 ± 1 sd analytical errors and ± 1 sd inter-laboratory variation. To determine the hydrolysis procedure that minimizes induced racemization while maximizing amino acid recovery, we hydrolyzed seven powdered molluscan fossils of different ages and genera for 0-48 h at 110°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°C is preferred.

Original languageEnglish (US)
Pages (from-to)987-1000
Number of pages14
JournalQuaternary Science Reviews
Volume17
Issue number11
DOIs
StatePublished - Nov 1998
Externally publishedYes

Fingerprint

reversed-phase liquid chromatography
liquid chromatography
fossils
amino acid
fossil
racemization
amino acids
hydrolysis
sampling
derivatization
geochronology
reproducibility
mollusc
molluscs
isomers
Chromatography
Amino Acids
Liquid
Fossil
plateaus

ASJC Scopus subject areas

  • Earth-Surface Processes

Cite this

A new procedure for determining DL amino acid ratios in fossils using reverse phase liquid chromatography. / Kaufman, Darrell S; Manley, William F.

In: Quaternary Science Reviews, Vol. 17, No. 11, 11.1998, p. 987-1000.

Research output: Contribution to journalArticle

@article{5b2c9082031248a2930587415f2cfc8c,
title = "A new procedure for determining DL amino acid ratios in fossils using reverse phase liquid chromatography",
abstract = "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 sample and precise stereoisomeric separations. At least nine pairs of DL-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 DL ratios in four fossils spanning a broad range of ages averages 7{\%} (n = 14-28) Asp and Glu DL 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 ± 1 sd analytical errors and ± 1 sd inter-laboratory variation. To determine the hydrolysis procedure that minimizes induced racemization while maximizing amino acid recovery, we hydrolyzed seven powdered molluscan fossils of different ages and genera for 0-48 h at 110°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°C is preferred.",
author = "Kaufman, {Darrell S} and Manley, {William F.}",
year = "1998",
month = "11",
doi = "10.1016/S0277-3791(97)00086-3",
language = "English (US)",
volume = "17",
pages = "987--1000",
journal = "Quaternary Science Reviews",
issn = "0277-3791",
publisher = "Elsevier Limited",
number = "11",

}

TY - JOUR

T1 - A new procedure for determining DL amino acid ratios in fossils using reverse phase liquid chromatography

AU - Kaufman, Darrell S

AU - Manley, William F.

PY - 1998/11

Y1 - 1998/11

N2 - 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 sample and precise stereoisomeric separations. At least nine pairs of DL-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 DL ratios in four fossils spanning a broad range of ages averages 7% (n = 14-28) Asp and Glu DL 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 ± 1 sd analytical errors and ± 1 sd inter-laboratory variation. To determine the hydrolysis procedure that minimizes induced racemization while maximizing amino acid recovery, we hydrolyzed seven powdered molluscan fossils of different ages and genera for 0-48 h at 110°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°C is preferred.

AB - 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 sample and precise stereoisomeric separations. At least nine pairs of DL-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 DL ratios in four fossils spanning a broad range of ages averages 7% (n = 14-28) Asp and Glu DL 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 ± 1 sd analytical errors and ± 1 sd inter-laboratory variation. To determine the hydrolysis procedure that minimizes induced racemization while maximizing amino acid recovery, we hydrolyzed seven powdered molluscan fossils of different ages and genera for 0-48 h at 110°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°C is preferred.

UR - http://www.scopus.com/inward/record.url?scp=0031735136&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0031735136&partnerID=8YFLogxK

U2 - 10.1016/S0277-3791(97)00086-3

DO - 10.1016/S0277-3791(97)00086-3

M3 - Article

AN - SCOPUS:0031735136

VL - 17

SP - 987

EP - 1000

JO - Quaternary Science Reviews

JF - Quaternary Science Reviews

SN - 0277-3791

IS - 11

ER -