title: Increasing the sensitivity of delta13C and delta15N abundance measurements by a high sensitivity elemental analyzer connected to an isotope ratio mass spectrometer.
abstract: A common elemental analyzer system connected to a temperature-controlled gas chromatography (GC) column and coupled to an isotope ratio mass spectrometer was improved to decrease the determination limit for a simultaneous stable isotope ratio measurement of nitrogen and carbon dioxide. The additional use of a special ashtray system to collect the combustion residuals permitted more time-efficient work. These modifications to the elemental analyzer allowed precise measurements to be made down to 1.5 microg nitrogen and 10 microg carbon for stable isotope analysis. Low system background values and an acceptable signal-to-noise ratio have made an additional blank correction for these low sample measurements unnecessary. We provide a precision of this stable isotope analysis for lowest amounts of 1.2-2 microg nitrogen with a standard deviation of +/-0.496 per thousand (n = 27) and for 8.2-15 microg carbon with a standard deviation of +/-0.257 per thousand (n = 31) across different sample runs under stipulated conditions. This application can be established in an automatic mode without cryofocusing procedures.
authors.affiliation: Leibniz-Institute for Marine Sciences at Kiel University, Düsternbrooker Weg 20, 24105 Kiel, Germany. thansen@ifm-geomar.de
authors.forename: T
authors.initials: T
authors.lastname: Hansen
authors.forename: U
authors.initials: U
authors.lastname: Sommer
mesh_terms: D002247:Carbon Isotopes / Q000032:analysis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006358:Hot Temperature; D013058:Mass Spectrometry / Q000295:instrumentation* / Q000379:methods; D009587:Nitrogen Isotopes / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000295:instrumentation* / Q000379:methods
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes