Dynamic olfactometry [UNI-EN13725:2004]
Determination odorous intensity of the samples
The samples are analyzed with the dynamic Olfactometry method for the index calculation SOER (Specific Odor Emission Rate) and OER (Odor Emission Rate). The determination of odorigeno load of the samples can be carried out with the integration Analyzer Sensory Pen3 when there are toxicological doubt samples. The determination of olfactometric units are performed with the aid of 6 rhino-analysts and dynamic olfactometer installed at a primary laboratory Dynamic Olfactometry.
What’s the dynamic olfactometry method?
The dynamic olfactometry according to the method of “forced choice”, is a method of measuring the concentration of odor of a sample and is based on its detection through the use of a panel of rhino-trained analysts. The instrument used is the dynamic olfactometer “OLFAKTOMAT- n6”. This tool allows the conduct of dynamic olfactometry sessions with a panel composed of six persons who can both smell and express their assessments in full compliance with European regulations UNI EN13725. The trend of the measurement is controlled by a PC, to which each station of smell is connected via handheld computer.
The criterion of the forced choice
The determination according to the criterion of “forced choice” means that each station of smell is equipped with two “ports.” From one of the two exits odorous air while the other reference only odorless air. The olfactometer from time to time, change the port from which it is forced out of the diluted mixture of smell. For each administration of smell each rinoanalista indicates, through a handheld device, from which of the two doors come feels the smell. The choice of rinoanalista is accompanied by a judgment: safe, unsafe or “at random.”
From the point of view of the result is considered valid the response of the rhino-analyst when the door from which the smell is properly recognized with certainty. The measurement starts with a dilution level such that no component of the panel is able to perceive the odor with certainty. In the subsequent administration of the odor dilution it is proportionally decreased until all rinoanalisti come to perceive the odor presence with certainty.
How the smell is defined?
A gaseous sample has a concentration of 1 OUE / m3 when it is at the threshold of perception, ie when 50% of the population, sniffing that sample, perceives an odor, while the remaining 50% do not perceive any. In practice, by applying the above definition, the charge of the smell of a generic sample is given by the number of dilutions that the latter must undergo in order to can no longer be perceived by the panelists.