title: Automated system for simultaneous analysis of delta(13)C, delta(18)O and CO(2) concentrations in small air samples.
abstract: In this paper we present an automated system for simultaneous measurement of CO(2) concentration, delta(13)C and delta(18)O from small (<1 mL) air samples in a short period of time (approximately 1 hour). This system combines continuous-flow isotope ratio mass spectrometry (CF-IRMS) and gas chromatography (GC) with an inlet system similar to conventional dual-inlet methods permitting several measurement cycles of standard and sample air. Analogous to the dual-inlet method, the precision of this system increases with the number of replicate cycles measured. The standard error of the mean for a measurement with this system is 0.7 ppm for the CO(2) concentration and 0.05 per thousand for the delta(13)C and delta(18)O with four replicate cycles and 0.4 ppm and 0.03 per thousand respectively with nine replicate cycles. The mean offset of our measurements from NOAA/CMDL analyzed air samples was 0.08 ppm for the CO(2) concentration, 0.01 per thousand for delta(13)C and 0.00 per thousand for delta(18)O. A specific list of the parts and operation of the system is detailed as well as some of the applications for micrometeorological and ecophysiological applications.
authors.affiliation: Carnegie Institution of Washington, Department of Plant Biology, 260 Panama Street, Stanford, CA 94305, USA. mribas@biosphere.stanford.edu
authors.forename: Miquel
authors.initials: M
authors.lastname: Ribas-Carbo
authors.forename: Chris
authors.initials: C
authors.lastname: Still
authors.forename: Joe
authors.initials: J
authors.lastname: Berry
mesh_terms: D000388:Air / Q000032:analysis*; D000465:Algorithms; D002245:Carbon Dioxide / Q000032:analysis*; D002247:Carbon Isotopes; D002849:Chromatography, Gas; D002940:Circadian Rhythm; D013058:Mass Spectrometry; D010103:Oxygen Isotopes; D010788:Photosynthesis
chemical_list: D002247:Carbon Isotopes; D010103:Oxygen Isotopes; D002245:Carbon Dioxide