A method for time-resolved calorespirometry of terrestrial samples

A new vessel for simultaneous isothermal calorimetry and respirometry (calorespirometry) on terrestrial (non-aqueous) samples has been developed. All types of small (<1 g) biological samples (insects, soil, leaves, fungi, etc.) can be studied. The respirometric measurements are made by opening and closing a valve to a vial inside the sample ampoule containing a carbon dioxide absorbent. Typically a 7 h measurement results in seven measurements of heat production rate, oxygen consumption and carbon dioxide production, which can be used to evaluate how the metabolic activity in a sample changes over time. Results from three experiments on leaves, a cut vegetable, and mold are given. As uncertainties--especially in the carbon dioxide production--tend to be quite high, improvements to the technique are also discussed.