Scientists from the Faculty of Agricultural Sciences have been involved in developing a trailblazing method for measuring smell from pig farms. [Photo: Lars Kruse, AU Kommunikation]

There is no doubt about it – pig farms do not smell like roses. Much more difficult to determine is how to measure the compounds that are the cause of the malodour. Scientists from the Faculty of Agricultural Sciences, Aarhus University, have found a solution. In collaboration with the Danish Agriculture and Food Council they have developed a method that can measure the compounds as they crop up.

Pig manure contains a wide range of stinky chemical compounds, including phenols, indoles, aldehydes, ketones, amines and volatile sulphur compounds. Until now, researchers have collected air samples in plastic bags, which they then have brought back to the laboratory for analysis by gas chromatography and mass spectrometry. This has, however, only provided a snapshot of the air’s content of odour compounds.

"Many of the compounds in the air from pig houses are very volatile. In addition, they are often only present in very small amounts. These conditions make it very hard to measure them," explains senior scientist Anders Feilberg from the Department of Biosystems Engineering at the Faculty of Agricultural Sciences.

The researchers therefore developed an alternative measurement method that can measure the air continuously. This is done using online proton transfer reaction mass spectrometry (PTR-MS). The technique is used for continuous identification and quantification of volatile compounds.