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Hydrogen isotope ratios of individua...

Sessions, Alex Lee.

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Hydrogen isotope ratios of individual organic compounds.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Hydrogen isotope ratios of individual organic compounds./
Author:	Sessions, Alex Lee.
Description:	150 p.
Notes:	Adviser: John M. Hayes.
Contained By:	Dissertation Abstracts International62-08B.
Subject:	Biogeochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3024276
ISBN:	0493360891

Hydrogen isotope ratios of individual organic compounds.
Sessions, Alex Lee.

Hydrogen isotope ratios of individual organic compounds. - 150 p.

Adviser: John M. Hayes.

Thesis (Ph.D.)--Indiana University, 2001.

We have developed a gas chromatography - pyrolysis - isotope-ratio-monitoring mass spectrometry system (irmGCMS) which can measure D/H ratios in individual organic compounds containing <10 nmol H2. Precision and accuracy for peaks with D/H at natural abundance are better than 5&permil;.

ISBN: 0493360891Subjects--Topical Terms:

545717
Biogeochemistry.

Hydrogen isotope ratios of individual organic compounds.
LDR:03798nam 2200325 a 45 001 929354
005 20110427
008 110427s2001 eng d
020 $a 0493360891
035 $a (UnM)AAI3024276
035 $a AAI3024276
040 $a UnM $c UnM
100 1 $a Sessions, Alex Lee. $3 1252838
245 1 0 $a Hydrogen isotope ratios of individual organic compounds.
300 $a 150 p.
500 $a Adviser: John M. Hayes.
500 $a Source: Dissertation Abstracts International, Volume: 62-08, Section: B, page: 3525.
502 $a Thesis (Ph.D.)--Indiana University, 2001.
520 $a We have developed a gas chromatography - pyrolysis - isotope-ratio-monitoring mass spectrometry system (irmGCMS) which can measure D/H ratios in individual organic compounds containing <10 nmol H2. Precision and accuracy for peaks with D/H at natural abundance are better than 5&permil;.
520 $a Correction for <math> <f> <rm>H+<inf>3</inf></rm></f> </math> in irmGCMS must deal with rapidly changing H2 signals. Corrections based on integrated peak height have a firm theoretical basis, but introduce errors for variable peak shapes and background signals. Pointwise correction of <math> <f> <rm>H+<inf>3</inf></rm></f> </math> is robust under all irmGCMS conditions. Accuracy of this correction is limited by time constants in signal-processing pathways, analog-to-digital conversion frequency, and peak widths. The H3 factor can be determined by a variety of equivalent methods, and is stable despite changing concentrations of CH4 and H2O. Equations are presented for estimating δD errors arising from uncertainties in <math> <f> <rm>H+<inf>3</inf></rm></f> </math> correction.
520 $a <italic>n</italic>-Alkyl lipids from higher plants are D-depleted relative to growth water by 113 to 226&permil;, and isoprenoid lipids by 142 to 376&permil;. Isotopic variations within compound classes from individuals are smaller than those between classes and between individuals. Hydrogen isotopic compositions of lipids are controlled by three factors: biosynthetic precursors, exchange accompanying biosynthesis, and hydrogenation.
520 $a Lipids from methanotrophic bacteria are D-depleted relative to water but enriched relative to methane, and are indistinguishable from plant lipids in isotopic composition. 33% of hydrogen in methanotroph lipids is derived from methane, although no C-bound H is transferred directly from methane. NADPH and H2O are possible intermediaries in this transfer. Systematic differences in δD exist between structurally similar lipids.
520 $a Isotopic fractionation in lipids from sulfate-reducing bacteria is equivalent to that in plants, despite fundamental differences in carbon fixation. H 2 probably does not contribute to lipid hydrogen in these organisms. δD of fatty acids varies significantly with chain length.
520 $a Exchange between icosane and D2O on mineral substrates yields exchange half-times of &sim;10ka at 60°C, and &sim;100ka at 7°C. Such experiments may be biased by heterogeneous exchange processes. Exchange on natural sediments containing 2–20% TOC provides no evidence that organic matter inhibits hydrogen exchange. Deuterium incorporation during reactions of cholestene indicates multiple processes leading to hydrogen exchange, and allows quantitative prediction of δD changes in steroids through diagenesis.
590 $a School code: 0093.
650 4 $a Biogeochemistry. $3 545717
690 $a 0425
710 2 0 $a Indiana University. $3 960096
773 0 $t Dissertation Abstracts International $g 62-08B.
790 $a 0093
790 1 0 $a Hayes, John M., $e advisor
791 $a Ph.D.
792 $a 2001
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3024276