Gas-transfer measurements using headspace analysis of propane

A sampling and analysis procedure for the tracer measurement of gas transfer is presented. Dissolved propane was used as a gas-transfer tracer. The propane samples were analyzed by a headspace gas chromatographic technique that was tested as an alternative to the purge-and-trap technique previously used for tracer measurements. Headspace analysis is simple, fast, precise, and does not require the extensive apparatus required by the purge-and-trap technique, so that any gas-chromatography laboratory can perform it. Headspace analysis was found to give excellent results with low uncertainty and a low limit of detection. Gastransfer measurements were performed on flow across a large-scale laboratory weir. A detailed uncertainty analysis was conducted for the transfer measurements. The results are applicable to other tracer measurements of gas transfer, and the headspace technique may be applied, with modifications, for the laboratory analysis of any volatile compound.