Introducing a ramped pyrolysis/oxidation‐ 14 CO 2 analysis system operated with mobile molecular sieve traps

Abstract A novel instrument for the thermal degradation of sedimentary organic matter was set up at the Alfred Wegener Institute (AWI) in Bremerhaven, Germany, with the aim of enabling Ramped Pyrolysis/Oxidation‐ 14 C analysis as direct CO 2 gas measurement. This is achieved by using self‐constructed multiposition molecular sieve (zeolite) trap systems, which are mobile and compatible with AWI's accelerator mass spectrometer as well as other CO 2 ‐producing devices. Here we provide a detailed description of the instrument setup, standard operating procedures, data reproducibility, and blank carbon contribution. The total blank of a standard run with a mass of 3.1 ± 0.2 μ gC and an F 14 C = 0.46 ± 0.03 is comparable to values published for other systems. We use a Bayesian statistical model in combination with the isotope dilution method to calculate the procedural blank and an isotopic mass balance for blank correction. This method is applied to correct F 14 C values measured for seven fractions of a natural, radiocarbon‐free standard material. The resulting corrected F 14 C values are indistinguishable from blank gas measurements. Using a range of different standard materials, the thermogram and 14 C measurement reproducibility are demonstrated. The method presented here constitutes a flexible and time‐saving alternative to cryogenic CO 2 trapping, facilitates high sample throughput and enables thermal degradation measurements of various sample types, including samples with ultra‐low organic carbon content.