Abstract
Several analytical techniques have been used in amino acid geochronology to measure the relative abundances of D- and L-enantiomers. During the past two decades, reverse-phase (RP) liquid chromatography has become most common, whereas ion-exchange (IE) liquid chromatography was widely used prior to the mid-1990s. This study is based on intra-lab paired analyses of RP and IE liquid chromatography to mathematically convert A/I (allo-isoleucine:isoleucine) values determined with IE to corresponding D/L values for comparison with new RP results. Pooled results of 340 paired IE and RP analyses show that A/I values can be confidently converted to equivalent D/L values for aspartic acid, glutamic acid, alanine, valine and isoleucine, with 2σ uncertainties of ±24–41% depending on the amino acid. For specific sample types including gastropod, bivalve, eggshell and whole rock, A/I can readily be converted to D/L aspartic acid and D/L glutamic acid with 2σ uncertainties of ±20% and 26%, respectively, using sample-type-specific relations. A/I is also reliably converted to D/L valine and D/L isoleucine with 2σ uncertainties of ±31 and 35%, respectively. Regression equations are provided to convert A/I to an equivalent D/L value for five amino acids, thereby enabling the large literature base of AAR results from IE chromatography to be compared and integrated with AAR results from RP chromatography.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1-6 |
| Number of pages | 6 |
| Journal | Quaternary Geochronology |
| Volume | 37 |
| DOIs | |
| State | Published - Feb 1 2017 |
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Keywords
- Amino acid racemization
- Isoleucine epimerization
- Quaternary geochronology
ASJC Scopus subject areas
- Geology
- Stratigraphy
- Earth and Planetary Sciences (miscellaneous)
Cite this
Converting A/I values (ion exchange) to D/L values (reverse phase) for amino acid geochronology. / Whitacre, Katherine E.; Kaufman, Darrell S; Kosnik, Matthew A.; Hearty, Paul J.
In: Quaternary Geochronology, Vol. 37, 01.02.2017, p. 1-6.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Converting A/I values (ion exchange) to D/L values (reverse phase) for amino acid geochronology
AU - Whitacre, Katherine E.
AU - Kaufman, Darrell S
AU - Kosnik, Matthew A.
AU - Hearty, Paul J.
PY - 2017/2/1
Y1 - 2017/2/1
N2 - Several analytical techniques have been used in amino acid geochronology to measure the relative abundances of D- and L-enantiomers. During the past two decades, reverse-phase (RP) liquid chromatography has become most common, whereas ion-exchange (IE) liquid chromatography was widely used prior to the mid-1990s. This study is based on intra-lab paired analyses of RP and IE liquid chromatography to mathematically convert A/I (allo-isoleucine:isoleucine) values determined with IE to corresponding D/L values for comparison with new RP results. Pooled results of 340 paired IE and RP analyses show that A/I values can be confidently converted to equivalent D/L values for aspartic acid, glutamic acid, alanine, valine and isoleucine, with 2σ uncertainties of ±24–41% depending on the amino acid. For specific sample types including gastropod, bivalve, eggshell and whole rock, A/I can readily be converted to D/L aspartic acid and D/L glutamic acid with 2σ uncertainties of ±20% and 26%, respectively, using sample-type-specific relations. A/I is also reliably converted to D/L valine and D/L isoleucine with 2σ uncertainties of ±31 and 35%, respectively. Regression equations are provided to convert A/I to an equivalent D/L value for five amino acids, thereby enabling the large literature base of AAR results from IE chromatography to be compared and integrated with AAR results from RP chromatography.
AB - Several analytical techniques have been used in amino acid geochronology to measure the relative abundances of D- and L-enantiomers. During the past two decades, reverse-phase (RP) liquid chromatography has become most common, whereas ion-exchange (IE) liquid chromatography was widely used prior to the mid-1990s. This study is based on intra-lab paired analyses of RP and IE liquid chromatography to mathematically convert A/I (allo-isoleucine:isoleucine) values determined with IE to corresponding D/L values for comparison with new RP results. Pooled results of 340 paired IE and RP analyses show that A/I values can be confidently converted to equivalent D/L values for aspartic acid, glutamic acid, alanine, valine and isoleucine, with 2σ uncertainties of ±24–41% depending on the amino acid. For specific sample types including gastropod, bivalve, eggshell and whole rock, A/I can readily be converted to D/L aspartic acid and D/L glutamic acid with 2σ uncertainties of ±20% and 26%, respectively, using sample-type-specific relations. A/I is also reliably converted to D/L valine and D/L isoleucine with 2σ uncertainties of ±31 and 35%, respectively. Regression equations are provided to convert A/I to an equivalent D/L value for five amino acids, thereby enabling the large literature base of AAR results from IE chromatography to be compared and integrated with AAR results from RP chromatography.
KW - Amino acid racemization
KW - Isoleucine epimerization
KW - Quaternary geochronology
UR - http://www.scopus.com/inward/record.url?scp=84992708792&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84992708792&partnerID=8YFLogxK
U2 - 10.1016/j.quageo.2016.10.004
DO - 10.1016/j.quageo.2016.10.004
M3 - Article
AN - SCOPUS:84992708792
VL - 37
SP - 1
EP - 6
JO - Quaternary Geochronology
JF - Quaternary Geochronology
SN - 1871-1014
ER -