Improvement of olfactometric measurement accuracy and repeatability by optimization of panel selection procedures

The EN 13725:2003, which standardizes the determination of odour concentration by dynamic olfactometry, fixes the limits for panel selection in terms of individual threshold towards a reference gas (n-butanol in nitrogen) and of standard deviation of the responses. Nonetheless, laboratories have som...

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Bibliographic Details
Published in:Water science and technology 2010-01, Vol.61 (5), p.1267-1278
Main Authors: Capelli, L, Sironi, S, Del Rosso, R, Céntola, P, Bonati, S
Format: Article
Language:English
Subjects:
1-Butanol - chemistry
Accuracy
Air Pollutants - analysis
Butanol
Clinical Laboratory Techniques
Environmental Monitoring - methods
Equipment Design
Europe
Evaluation
Gases
Humans
Laboratories
Measurement
Nitrogen - chemistry
Odor
Odour
Olfaction
Olfactometers
Olfactory Perception
Perception
Procedures
Quality Control
Reference Standards
Reproducibility of Results
Smell
Threshold limits
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Summary:The EN 13725:2003, which standardizes the determination of odour concentration by dynamic olfactometry, fixes the limits for panel selection in terms of individual threshold towards a reference gas (n-butanol in nitrogen) and of standard deviation of the responses. Nonetheless, laboratories have some degrees of freedom in developing their own procedures for panel selection and evaluation. Most Italian olfactometric laboratories use a similar procedure for panel selection, based on the repeated analysis of samples of n-butanol at a concentration of 60 ppm. The first part of this study demonstrates that this procedure may originate a sort of "smartening" of the assessors, which means that they become able to guess the right answers in order to maintain their qualification as panel members, independently from their real olfactory perception. For this reason, the panel selection procedure has been revised with the aim of making it less repetitive, therefore preventing the possibility for panel members to be able to guess the best answers in order to comply with the selection criteria. The selection of new panel members and the screening of the active ones according to this revised procedure proved this new procedure to be more selective than the "standard" one. Finally, the results of the tests with n-butanol conducted after the introduction of the revised procedure for panel selection and regular verification showed an effective improvement of the laboratory measurement performances in terms of accuracy and precision.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2010.023