Rapid, automated analysis of 13C and 18O of CO2 in gas samples by continuous-flow, isotope ratio mass spectrometry.
A rapid automated method for isotopic analysis of 13C and 18O in CO2 has been developed. A variety of gas samples containing CO2 can be swept from serological tubes into a helium carrier flow; impurities are separated on a GC column so that a pure pulse of CO2 in He flows into the mass spectrometer. Isotopic ratio determinations are carried out as the pulse passes through the mass spectrometer, allowing a sample to be measured approximately every 4 min. A double, concentric needle-probe is used to flush the sample from the tube so that 100% sample recovery is achieved, maximizing sensitivity and preventing the possibility of fractionation. The precision of the technique, sigma(m-1), is better than 0.2% (0.0002 atom per cent excess) for 13C and 0.4% (0.83 p.p.m.) for 18O for 10 micromol of CO2 at natural abundance. Samples containing only atmospheric concentrations of CO2 can also be analyzed.
Prosser
S J
SJ
Europa Scientific Ltd, Crewe, Cheshire, UK.
Brookes
S T
ST
Linton
A
A
Preston
T
T
D001944:Breath Tests / Q000295:instrumentation* / Q000379:methods; D002245:Carbon Dioxide / Q000737:chemistry*; D002247:Carbon Isotopes; D006801:Humans; D066298:In Vitro Techniques; D013058:Mass Spectrometry / Q000379:methods; D010103:Oxygen Isotopes; D013997:Time Factors
D002247:Carbon Isotopes; D010103:Oxygen Isotopes; D002245:Carbon Dioxide