Moving-Wire Device for Carbon Isotopic Analyses of Nanogram Quantities of Nonvolatile Organic Carbon
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- 作者：Alex L. Sessions ; Sean P. Sylva ; and John M. Hayes
- 刊名：Analytical Chemistry
- 出版年：2005
- 出版时间：October 15, 2005
- 年：2005
- 卷：77
- 期：20
- 页码：6519 - 6527
- 全文大小：289K
- 年卷期：v.77,no.20(October 15, 2005)
- ISSN：1520-6882
文摘
We describe a moving-wire analyzer for measuring P>13C indissolved, involatile organic materials. Liquid samples arefirst deposited and dried on a continuously spooling nickelwire. The residual sample is then combusted as the wiremoves through a furnace, and the evolved CO2 is analyzedby continuous-flow isotope ratio mass spectrometry. Atypical analysis requires 1 
L of sample solution andproduces a CO2 peak ~5 s wide. The system can measure"bulk" 
13C values of ~10 nmol of organic carbon withprecision better than 0.2”. For samples containing ~1nmol of C, precision is ~1”. Precision and sensitivityare limited mainly by background noise derived fromcarbon within the wire. Instrument conditions minimizingthat background are discussed in detail. Accuracy is betterthan 0.5” for nearly all dissolved analytes tested, including lipids, proteins, nucleic acids, sugars, halocarbons,and hydrocarbons. The sensitivity demonstrated here for13C measurements represents a ~1000-fold improvementrelative to existing elemental analyzers and should allowthe use of many new preparative techniques for collectingand purifying nonvolatile biochemicals for isotopic analysis.
L of sample solution andproduces a CO2 peak ~5 s wide. The system can measure"bulk" 13C values of ~10 nmol of organic carbon withprecision better than 0.2”. For samples containing ~1nmol of C, precision is ~1”. Precision and sensitivityare limited mainly by background noise derived fromcarbon within the wire. Instrument conditions minimizingthat background are discussed in detail. Accuracy is betterthan 0.5” for nearly all dissolved analytes tested, including lipids, proteins, nucleic acids, sugars, halocarbons,and hydrocarbons. The sensitivity demonstrated here for13C measurements represents a ~1000-fold improvementrelative to existing elemental analyzers and should allowthe use of many new preparative techniques for collectingand purifying nonvolatile biochemicals for isotopic analysis.