title: Optimization of automated gas sample collection and isotope ratio mass spectrometric analysis of delta(13)C of CO(2) in air.
abstract: The application of (13)C/(12)C in ecosystem-scale tracer models for CO(2) in air requires accurate measurements of the mixing ratios and stable isotope ratios of CO(2). To increase measurement reliability and data intercomparability, as well as to shorten analysis times, we have improved an existing field sampling setup with portable air sampling units and developed a laboratory setup for the analysis of the delta(13)C of CO(2) in air by isotope ratio mass spectrometry (IRMS). The changes consist of (a) optimization of sample and standard gas flow paths, (b) additional software configuration, and (c) automation of liquid nitrogen refilling for the cryogenic trap. We achieved a precision better than 0.1 per thousand and an accuracy of 0.11 +/- 0.04 per thousand for the measurement of delta(13)C of CO(2) in air and unattended operation of measurement sequences up to 12 h.
authors.affiliation: Institute of Plant Sciences, ETH Zurich, Universitaetstrasse 2, CH-8092 Zurich, Switzerland. matthias.zeeman@ipw.agrl.ethz.ch
authors.forename: Matthias J
authors.initials: MJ
authors.lastname: Zeeman
authors.forename: Roland A
authors.initials: RA
authors.lastname: Werner
authors.forename: Werner
authors.initials: W
authors.lastname: Eugster
authors.forename: Rolf T W
authors.initials: RT
authors.lastname: Siegwolf
authors.forename: Günther
authors.initials: G
authors.lastname: Wehrle
authors.forename: Joachim
authors.initials: J
authors.lastname: Mohn
authors.forename: Nina
authors.initials: N
authors.lastname: Buchmann
mesh_terms: D000388:Air / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis* / Q000737:chemistry; D002247:Carbon Isotopes / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012107:Research Design; D012680:Sensitivity and Specificity
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide