An open-source, automated, gas sampling peripheral for laboratory incubation experiments
Spectroscopic instruments are becoming increasingly popular for measuring the isotopic composition and fluxes of a wide variety of gases in both field and laboratory experiments. The popularity of these instruments has created a need for automated multiplexers compatible with the equipment. While there are several such peripherals commercially available, they are currently limited to only a small number of samples (<= 16), which is insufficient for some studies. To support researchers in constructing custom, larger-scale systems, we present our design for a scalable gas sampling peripheral that can be programmed to autonomously sample up to 56 vessels – the “multiplexer”. While originally designed to be used with a Picarro cavity ring-down spectroscopy system, the multiplexer design and data processing approach implemented can be easily adapted to serve as a gas sampling/delivery platform for a wide variety of instruments including other cavity ring-down systems and infra-red gas analyzers. We demonstrate the basic capabilities of the multiplexer by using it to autonomously sample head-space CO2 from 14 laboratory-incubated soils amended with 13C-enriched pyrogenic organic matter for analysis in a Picarro G2201-i cavity ring-down spectroscopy system. This dataset includes the raw data and log files generated during the demonstration run of the instrument constructed and the data processing script necessary to analyze the data. Raw data includes outputs from a Picarro G2131i cavity ringdown spectrometer and includes all data needed to calculate respiration rates and carbon mineralization using the included processing script.