Interlaboratory Comparison Olfactometry - 2007 

(Proficency Test, Round Robin) 

Announcement 2007.pdf

Building on the experience of organizing successful interlaboratory comparisons for olfactometry in 2003 and 2005 (EN 13725:2003) and in 2004/2006 (VDA 270) OLFAtec GmbH is again inviting participation in an interlaboratory comparison for olfactometry laboratories on the basis of EN 13725:2003. 

Interlaboratory comparisons are acquiring an ever growing significance as an element of quality assurance, and is a required part of QA/QC for laboratories that are accredited according to quality standard ISO/IEC 17025. 

Since December 2005 OLFAtec GmbH is an accredited inspection body according to DIN EN ISO/IEC 17020:2004 in conjunction with ILAC-G13 as well as ISO/IEC Guide 43-1. The latest audit for this accreditation was successfully accomplished in December 2006, with a strong emphasis by the audit team on the correct application of statistical methods for evaluation of results. The scope of the accreditation refers specifically to the realisation of interlaboratory tests in the field of dynamic olfactometry. As a result this 2007 interlaboratory comparison will be conducted under accreditation for the first time. 
Another novelty is the involvement of a technical and organisational comittee to advise OLFAtec GmbH on the technical design of the interlaboratory test. The committee of external consultants consisted of members of the working group responsible for drafting EN13725, CEN/TC 264 „Air Quality“ WG2 ‘Olfactometry’: Mr Paul Heeres (auditor and consultant) as well as Ton van Harreveld (quality manager and CEO of the Odournet group). Their in depth knowledge was built over the years, from participating in the successful drafting of the EN 13725 standard, and from the organising a succession of interlaboratory tests in the field of dynamic olfactometry, both in the Netherlands and on an international level. 

One of the recommendations of the advisory board was to encourage the participants of the interlaboratory test to appoint an independent observer to monitor the conditioning of the samples and the actual olfactometric measurement procedure, to ensure transparency. Laboratories who wish to take the lead in providing transparency to their clients could consider inviting internal or external auditors or, within Germany, the representatives of the notifying bodies for this task.

The committee members will not have any access to the participants’ identifiable results. 

As in previous interlaboratory comparisons is 2003 and 2005 the olfactometric measurements required will be carried out in the own laboratories of participants. That means, the actual measurements will be done by regular staff at the participants´ laboratories to characterise relevant quality features on the spot. 

The objective of the interlaboratory test 2007 is

to verify the quality parameters of the testing laboratories in determining odour concentrations following EN 13725:2003 (for participants in the RV PLUS variant) and to provide all participants them with a level check for three compounds, as an international comparison. To achieve this the participants will:

• Determine different odour concentrations for three compounds, of which one will be presented in two concentration levels
• to asses the precision r and accuracy A for 1-butanol of your laboratory according to EN 13725:2003 (this is possible only for participants in the RV PLUS option)

The concept of the interlaboratory test 2007 
All measurements are carried out as follows:

• Local measurement at the regular odour laboratory of participants (using their own olfactometer, panel members, the measurement room and other laboratory equipment) 
• Odour samples will be sent by OLFAtec GmbH in suitable disposable pressurised gas cylinders (Minicans). Sample bags will be provided as well. The laboratories will transfer the reference gas samples from the Minicans to the odour sample bags themselves
• The actual measurements will be carried out within a given time frame of 5 working days 

There are 2 options for participants within the scope of the 2007 interlaboratory comparison:

1. RV BASIC
2. RV PLUS

Having chosen the RV BASIC option each laboratory will receive 4 odour samples for analysis (2 different concentrations of 1-Butanol, 1 THT (Tetrahydrotiophene) and 1 S-FREE (a three component natural gas odorant) for the exploration. At least one odour measurement following EN 13725:2003 is to be performed for each particular sample. The objective is to derive the mean value of the odour concentration as exactly as possible from the joint results of laboratories that have been ascertained to operate according to EN 13725. This allows all laboratories to compare their result with the best estimate of the mean. The implementation of RV BASIC is equivalent to the RV Standard option in 2003 and 2005.

Participating laboratories opting for the RV PLUS option will have the opportunity to ascertain that the quality parameters required by EN13725:2003, specifically precision r and accuracy A for 1-Butanol are within the required criteria. 
Only laboratories participating in the RV PLUS option will be able to provide evidence on the laboratory’s ability to satisfy the lab-specific criteria of EN 13725:2003. For this purpose RV PLUS participants will receive another eight 1-Butanol samples at different concentrations, in addition to the RV BASIC gases.

Time Schedule:

• Please confirm your participation by April 30, 2007 at the latest. (Please mind the differentiated price list!)
• The testing for the interlaboratory comparison will be carried out between June 18 and June 22, 2007, (calendar week 25)

OLFAtec GmbH will provide the following services:

• Design, organisation and planning
• Shipment of the odour samples, bag material included, and detailed instructions to process the samples
• Evaluation of the measuring results. Each participant will receive the relation of his own results with regard to the mean value results or reference value (for 1-butanol), a coded table of results of all laboratories, and a certificate of participation.

Data analysis

Based on information provided by participating laboratories in a questionnaire on their level of compliance with the requirements of EN 13725:2003 and relevant quality system accreditations the participating laboratories will be classified into two categories. This classification is to be used only for the evaluation of statistical parameters, in particular the mean result for THT and S-FREE, and it does not have any reflect a rating of the lab’s quality in a general sense. The results of the category 1 laboratories will be taken into account for detection of the relevant mean values for THT and S-FREE. In detail:

RV BASIC
1. The results for 1-Butanol will be evaluated, relative to the reference value of 123 ug/m³.
2. A robust mean value for THT and S-FREE will be ascertained by applying the M-estimator according to HAMPEL (cp. DIN 38402-45) to the values of the laboratories that are in category 1 and can be considered to be EN13725:2003 compliant. The results of each participating laboratory will be evaluated, relative to this robust estimate for the mean value.

RV PLUS
in addition to the RV BASIC results, the laboratories participating in the RV PLUS option will receive their specific value for accuracy A and the precision r , calculated according to EN 13725:2003. The result will be evaluated relative to the criteria set in the standard.

In addition to the sensory data the participants will receive the results of instrumental analysis of the concentration of the distributed reference gases (retain sample), that will be carried out during the test period (calendar week 25). The certificates issued for the Certified Reference Materials of 1-Butanol in nitrogen used for the preparation of the Minicans will be made available to the participants.

Costs:
The participation fees are as follows:

• RV BASIS (registration until 15 March 2007): 1.450,00 EUR
• RV BASIS (registration until 30 April 2007): 1.750,00 EUR
• RV PLUS (registration until 15 March 2007): 3.050,00 EUR
• RV PLUS (registration until 30 April 2007): 3.450,00 EUR

Please note:

• VAT (currently 19%) will be charged to participants within Germany
• VAT (currently 19%) will also be charged to participants inside of the EU who do not provide a valid value added tax ID number
• Additional freight charges will apply to participants located outside the EU

Registration