In:
Rapid Communications in Mass Spectrometry, Wiley, Vol. 33, No. 20 ( 2019-10-30), p. 1553-1564
Abstract:
Nitrous oxide (N 2 O) is an atmospheric trace gas regulating Earth's climate, and is a key intermediate of many nitrogen cycling processes in aquatic ecosystems. Laser‐based technology for N 2 O concentration and isotopic/isotopomeric analyses has potential advantages, which include high analytical specificity, low sample size requirement and reduced cost. Methods An autosampler with a purge‐and‐trap module is coupled to a cavity ring‐down spectrometer to achieve automated and high‐throughput measurements of N 2 O concentrations, N 2 O isotope ratios (δ 15 N bulk and δ 18 O values) and position‐specific isotopomer ratios (δ 15 N α and δ 15 N β values). The system provides accuracy and precision similar to those for measurements made by traditional isotope ratio mass spectrometry (IRMS) techniques. Results The sample sizes required were 0.01–1.1 nmol‐N 2 O. Measurements of four N 2 O isotopic/isotopomeric references were cross‐calibrated with those obtained by IRMS. With a sample size of 0.50 nmol‐N 2 O, the measurement precision (1 σ ) for δ 15 N α , δ 15 N β , δ 15 N bulk and δ 18 O values was 0.61, 0.33, 0.41 and 0.43‰, respectively. Correction schemes were developed for sample size‐dependent isotopic/isotopomeric deviations. The instrumental system demonstrated consistent measurements of dissolved N 2 O concentrations, isotope/isotopomer ratios and production rates in seawater. Conclusions The coupling of an autosampler with a purge‐and‐trap module to a cavity ring‐down spectrometer not only significantly reduces sample size requirements, but also offers comprehensive investigation of N 2 O production pathways by the measurement of natural abundance and tracer level isotopes and isotopomers. Furthermore, the system can perform isotopic analyses of dissolved and solid nitrogen‐containing samples using N 2 O as the analytical proxy.
Type of Medium:
Online Resource
ISSN:
0951-4198
,
1097-0231
Language:
English
Publisher:
Wiley
Publication Date:
2019
detail.hit.zdb_id:
2002158-6
detail.hit.zdb_id:
58731-X
SSG:
11
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