In Europe, dynamic olfactometry, is described in detail by the European standard EN 13725. This standard was last released in 2003 and is currently under review for revision. Key elements of this standard are the focus on quality criteria for precision and repeatability. The EN13725 tries to link these values to standard values of n-butanol in nitrogen. It is assumed in this standard that whenever a laboratory complies with the overall sensory quality criteria for n-butanol, the quality level is transferable to other, environmental, odors.
The Standard describes the different test modes such as Triangular Forced Choice, Binary Forced Choice, and Yes/No method for determining the true odour concentration of a sample bag. Many aspects of the testing is defined including:
- Number of panelists (min 4)
- Acceptance criteria of each panelist
- Design of teh olfactometer in presentation air flow (20 lpm), presentation air speed, minimum dilution, maximum dilution, and maximum step size.
- Calculation of individual detection thresholds and overall detection threshold.
- Design of the testing room including temperature and humidity
- materials used in the olfactometer
One of the main objectives of the EN13725 standard is the inter-laboratory testing and panelist screening.
While the EN13725 does cover sampling, it is generally accepted that sampling techniques require much greater attention in the next revision of the standard. The standard does provide guidance on the type of sample bags (nalophan, Tedlar, PTFE, etc) and on the dilution devices required (stack diluting sampler, flux chamber, static hood, etc).