In:
Rapid Communications in Mass Spectrometry, Wiley, Vol. 27, No. 14 ( 2013-07-30), p. 1649-1659
Abstract:
High‐temperature, conversion‐reduction (HTC) systems convert hydrogen and oxygen in materials into H 2 and CO for δ 2 H and δ 18 O measurements by isotope ratio mass spectrometry. HTC of nitrogen‐ and sulfur‐bearing materials produces unintended byproduct gases that could affect isotope analyses by: (1) allowing isotope exchange reactions downstream of the HTC reactor, (2) creating isobaric or co‐elution interferences, and (3) causing deterioration of the chromatography. This study characterizes these HTC byproducts. METHODS A HTC system (ThermoFinnigan TC/EA) was directly connected to a gas chromatograph/quadrupole mass spectrometer in scan mode ( m/z 8 to 88) to identify the volatile products generated by HTC at conversion temperatures of 1350 °C and 1450 °C for a range of nitrogen‐ and sulfur‐bearing solids [keratin powder, horse hair, caffeine, ammonium nitrate, potassium nitrate, ammonium sulfate, urea, and three nitrated organic explosives (PETN, RDX, and TNT)]. RESULTS The prominent HTC byproduct gases include carbon dioxide, hydrogen cyanide, methane, acetylene, and water for all nitrogen‐bearing compounds, as well as carbon disulfide, carbonyl sulfide, and hydrogen sulfide for sulfur‐bearing compounds. The 1450 °C reactor temperature reduced the abundance of most byproduct gases, but increased the significant byproduct, hydrogen cyanide. Inclusion of a post‐reactor chemical trap containing Ascarite II and Sicapent, in series, eliminated the majority of byproducts. CONCLUSIONS This study identified numerous gaseous HTC byproducts. The potential adverse effects of these gases on isotope ratio analyses are unknown but may be mitigated by higher HTC reactor temperatures and purifying the products with a purge‐and‐trap system or with chemical traps. Published in 2013. This article is a U.S. Government work and is in the public domain in the USA.
Type of Medium:
Online Resource
ISSN:
0951-4198
,
1097-0231
Language:
English
Publisher:
Wiley
Publication Date:
2013
detail.hit.zdb_id:
2002158-6
detail.hit.zdb_id:
58731-X
SSG:
11
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