Detection threshold is essentially the minimum amount of odorant that can be perceived (smelled). This minimum amount represents the odour concentration and is a measurement of 1 OU (1 odour unit) or 1 OU/m3 or 1 OUE/m3. This is determined by a selected panel and usually represents 50% of the population.
According to the EN13725 standard, detection threshold represents for a sample: the dilution factor at which the sample has a probability of 0.5 of being detected under the condition s of the test. According to E679-04, detection threshold represents: the lowest concentration of a substance in a medium relating to the lowest physical intensity at which a stimulus is detected.
An odour is presented to a panel in order to judge at which dilution the sample can initially being detected (smelled). The odours are presented in a decreasing diluted series of samples (neutral gas and odourant) until the dilution at which detection occurs.