The existing standard EN 13725, first published in 2003, requires revision. The 9th meeting of the group that deals with the revision of the EN 13725 just took place in Antwerp, Belgium. The members of the Task Group that is dealing with the calculation of the uncertainty agreed that n-butanol is probably not representative for all environmental odours. In addition, n-butanol does not necessarily describe the sense of smell for a panelist very well. The new Standard EN 13725 will define a new procedure to design and test any new reference odorant. Is this the end of n-butanol as a reference material for olfactometry?
The odour concentration of an odorous gas sample is determined by presenting a panel of selected and screened human subjects with that sample, varying the concentration by diluting with neutral gas, in order to determine the dilution factor at the 50 % detection threshold. At that dilution factor the odour concentration is 1 ouE/m3 by definition.