Abstract
We have developed a system for analyzing nanomole-sized quantities of silicate-derived N2 by carrier-gas methods, through combination of a metal high-vacuum extraction line fabricated at Lehigh University and a commercially available continuous-flow, gas chromatography interface (the Finnigan Gas Bench II). This work involves heating of samples to 950-1050 °C (depending on the material being analyzed), with Cu metal and Cu oxide reagents, in evacuated and sealed 6 mm (o.d.) quartz tubes. Uncertainties (expressed as 1σ for ≥ 3 replicate analyses of both internal silicate standards and unknowns) are generally less than 5% for N concentrations and on the order of 0.15‰ δ15N for samples with > 5 ppm N. At current blank levels (minimum overall system blank of 3.8 ± 0.2 nmol N2 with a δ15Nair value of - 7.3 ± 0.4‰, mean ± 1σ), uncertainty in δ15N increases to ∼ 0.6‰ for samples with 1-2 ppm N. Practical minimum sample size, taking into account blanks and other factors affecting N2 transfer, is now ∼ 10 nmol, two orders of magnitude smaller than that previously possible in our laboratory using dual-inlet microvolume methods (∼ 1 μmol). These methods, which can be employed in any laboratory able to undertake continuous flow techniques (with a dynamic-vacuum, isotope ratio mass spectrometer), afford increased spatial resolution in some studies and open up many new avenues of investigation previously impeded by the absence of sufficiently N-rich materials.
| Original language | English |
|---|---|
| Pages (from-to) | 1-10 |
| Number of pages | 10 |
| Journal | Chemical Geology |
| Volume | 240 |
| Issue number | 1-2 |
| DOIs | |
| Publication status | Published - May 15 2007 |
| Externally published | Yes |
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Keywords
- Carrier gas
- Mass spectrometry
- Nitrogen isotopes
- Oceanic basalt
ASJC Scopus subject areas
- Geology
- Geochemistry and Petrology
Cite this
Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis of nanomole quantities of silicate nitrogen. / Edward Bebout, Gray; Idleman, Bruce D.; Li, Long; Hilkert, Andreas.
In: Chemical Geology, Vol. 240, No. 1-2, 15.05.2007, p. 1-10.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis of nanomole quantities of silicate nitrogen
AU - Edward Bebout, Gray
AU - Idleman, Bruce D.
AU - Li, Long
AU - Hilkert, Andreas
PY - 2007/5/15
Y1 - 2007/5/15
N2 - We have developed a system for analyzing nanomole-sized quantities of silicate-derived N2 by carrier-gas methods, through combination of a metal high-vacuum extraction line fabricated at Lehigh University and a commercially available continuous-flow, gas chromatography interface (the Finnigan Gas Bench II). This work involves heating of samples to 950-1050 °C (depending on the material being analyzed), with Cu metal and Cu oxide reagents, in evacuated and sealed 6 mm (o.d.) quartz tubes. Uncertainties (expressed as 1σ for ≥ 3 replicate analyses of both internal silicate standards and unknowns) are generally less than 5% for N concentrations and on the order of 0.15‰ δ15N for samples with > 5 ppm N. At current blank levels (minimum overall system blank of 3.8 ± 0.2 nmol N2 with a δ15Nair value of - 7.3 ± 0.4‰, mean ± 1σ), uncertainty in δ15N increases to ∼ 0.6‰ for samples with 1-2 ppm N. Practical minimum sample size, taking into account blanks and other factors affecting N2 transfer, is now ∼ 10 nmol, two orders of magnitude smaller than that previously possible in our laboratory using dual-inlet microvolume methods (∼ 1 μmol). These methods, which can be employed in any laboratory able to undertake continuous flow techniques (with a dynamic-vacuum, isotope ratio mass spectrometer), afford increased spatial resolution in some studies and open up many new avenues of investigation previously impeded by the absence of sufficiently N-rich materials.
AB - We have developed a system for analyzing nanomole-sized quantities of silicate-derived N2 by carrier-gas methods, through combination of a metal high-vacuum extraction line fabricated at Lehigh University and a commercially available continuous-flow, gas chromatography interface (the Finnigan Gas Bench II). This work involves heating of samples to 950-1050 °C (depending on the material being analyzed), with Cu metal and Cu oxide reagents, in evacuated and sealed 6 mm (o.d.) quartz tubes. Uncertainties (expressed as 1σ for ≥ 3 replicate analyses of both internal silicate standards and unknowns) are generally less than 5% for N concentrations and on the order of 0.15‰ δ15N for samples with > 5 ppm N. At current blank levels (minimum overall system blank of 3.8 ± 0.2 nmol N2 with a δ15Nair value of - 7.3 ± 0.4‰, mean ± 1σ), uncertainty in δ15N increases to ∼ 0.6‰ for samples with 1-2 ppm N. Practical minimum sample size, taking into account blanks and other factors affecting N2 transfer, is now ∼ 10 nmol, two orders of magnitude smaller than that previously possible in our laboratory using dual-inlet microvolume methods (∼ 1 μmol). These methods, which can be employed in any laboratory able to undertake continuous flow techniques (with a dynamic-vacuum, isotope ratio mass spectrometer), afford increased spatial resolution in some studies and open up many new avenues of investigation previously impeded by the absence of sufficiently N-rich materials.
KW - Carrier gas
KW - Mass spectrometry
KW - Nitrogen isotopes
KW - Oceanic basalt
UR - http://www.scopus.com/inward/record.url?scp=34147175570&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34147175570&partnerID=8YFLogxK
U2 - 10.1016/j.chemgeo.2007.01.006
DO - 10.1016/j.chemgeo.2007.01.006
M3 - Article
AN - SCOPUS:34147175570
VL - 240
SP - 1
EP - 10
JO - Chemical Geology
JF - Chemical Geology
SN - 0009-2541
IS - 1-2
ER -