Determination of the Odour Concentration and Odour Intensity of a Mixture of Odorous Substances by Chemical Concentrations: a Comparison of Methods

摘要

The assessment of the odour concentration of a mixture of odorous substances is a long lasting problem. Dueto the fact that the concentration measurements of chemical substances can be done on a continuous basis,these empirical data are often used to assess the odour concentration of the mixture of these compounds as asubstitute of direct odour measurements. Several concepts with increasing complexity are in use for thispurpose. Four methods – direct use of measured concentrations, the sum of the odour activity value SOAV,the sum of the odour intensities SOI and the equivalent odour concentration EOC - to convert theconcentrations of single substances to the odour concentrations and odour intensities of an odorous mixtureare investigated. The methods are compared with olfactometric measurements of seven substances as wellas their mixtures. The results indicate that the SOI and EOC conversion methods deliver reliable values.These two methods use not only the odour threshold concentration but also the slope of the Weber-Fechnerlaw. Due to the fact that no additional olfactometric measurements are necessary, they fulfil the criteria of anobjective conversion.