Processing of samples by ramped oxidation at the NEIF Radiocarbon Laboratory, SUERC: Recent technical advances

Carbon occurs as organic and inorganic matter in numerous complex forms and mixtures. Thermal separation of sample mixtures (e.g. sediment or soil), coupled with radiocarbon analysis, is a valuable approach for investigating the source, residence time, or age of different carbon components. At the NEIF Radiocarbon Laboratory we have built equipment for thermally separating samples for radiocarbon analysis using ramped oxidation. The original instrumentation has been successfully tested and validated for the purpose of partitioning samples based on their temperature of thermal decomposition, and for reliable radiocarbon measurement of different sample components. However, the original configuration of our instrument has limitations; a single analysis takes 2–3 hours, and an operator must be present to manually isolate samples from the required temperature ranges. To address this, we have upgraded our ramped oxidation equipment to include computer-controlled solenoid valves. These are activated according to a user-defined sampling scheme which enables autonomous collection of thermally partitioned samples. Here, we describe the latest improvements and present thermograms showing compatibility with the previous version of our equipment. This includes measurements of the radiocarbon background of the equipment, and results for known 14 C-content radiocarbon standards. These demonstrate the reliability of the new configuration of our equipment for radiocarbon measurements.