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An evaluation of alumina reaction tube conditioning for high-precision (2) H/(1) H isotope measurements via gas chromatography/thermal conversion/isotope ratio mass spectrometry.
MedLine Citation:
PMID:  23059873     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
RATIONALE: The condition of the pyrolysis reactor is very important for obtaining stable, precise hydrogen isotopic ratios using gas chromatography/thermal conversion/isotope ratio mass spectrometry (GC/TC/IRMS). However, few studies of the conditioning process have been conducted, and little is known about the best methods for high-precision hydrogen isotope analysis.
METHODS: We investigated δ(2) H variations and observed the changes in carbon coating using six different conditioning methods for the pyrolysis alumina tube: (i) no treatment; (ii) conditioning with 4 μL hexane; (iii) conditioning with 2 μL hexane; (iv) conditioning with 2 μL hexane followed by backflushing overnight; (v) conditioning with 10 s of backflushing with methane; (vi) conditioning with 3 s of backflushing with methane.
RESULTS: Conditioning the alumina tube can improve the pyrolysis efficiency of organic compounds because a moderate amount of carbon acts as a catalyst in high-temperature regions of the alumina tube. Carbon actually flows in the tube and is difficult to confine to the high-temperature region. Insufficient amounts of carbon in the high-temperature regions lead to incomplete pyrolysis of organic compounds and lower δ(2) H values due to kinetic fractionation of hydrogen isotopes. In contrast, excess hexane or methane can lead to higher δ(2) H values, probably due to enrichment of deuterium in the hydrocarbon residue.
CONCLUSIONS: The δ(2) H values obtained by Method 6 are closest to the TC/EA δ(2) H values and are more precise than those obtained by other methods, perhaps because this method introduces a moderate, consistent amount of carbon with each sample injection. Copyright © 2012 John Wiley & Sons, Ltd.
Authors:
Yunning Cao; Weiguo Liu; Peter E Sauer; Zheng Wang; Zheng-Hua Li
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Rapid communications in mass spectrometry : RCM     Volume:  26     ISSN:  1097-0231     ISO Abbreviation:  Rapid Commun. Mass Spectrom.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-10-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8802365     Medline TA:  Rapid Commun Mass Spectrom     Country:  England    
Other Details:
Languages:  eng     Pagination:  2577-83     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 John Wiley & Sons, Ltd.
Affiliation:
State Key Lab of Loess and Quaternary Geology, IEE, CAS, Xi'an, 710075, China.
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