Indicative evaluation of the measurement methods

For indicative evaluation of the published measurement methods, they were divided into a total of three categories to permit selection of the most suitable methods for further processing. The methods are based on the criteria of EN 482.

Category A: The method satisfies the general criteria of EN 482, and the specific requirements of CEN/TR 17055 and/or the EN 13205 series, where applicable.

Category B: The validation data are incomplete, but the measurement method has the potential to satisfy the general requirements of EN 482,and the specific requirements of CEN/TR 17055 and/or the EN 13205 series, where applicable.

Category C: The method fails to satisfy the requirements of EN 482 and lacks the potential to satisfy them.

Category "C" methods are not normally included in the database. However, should no category "A" or "B" method be available, a category "C" method is included but not evaluated further. Table 1 shows the criteria for indicative evaluation of methods.

Table 1: Criteria for indicative evaluation of the analysis methods

Method characteristic Requirement Implementation
Source of the method Published in a recognized source Required
Structure of the method description ISO 78-2
DIN EN 482 Annex B		 The most important parts must be included
Sampling requirements Statement of the sampling conditions Required
For aerosols, the requirements concerning aerosol sampling systems for the inhalable and respirable fractions must be observed
Transport and storage Description Required
Particularly for critical substances
Sample preparation Description Required
Analytical technique Description Required
Working range of the method Requirement of EN 482:
0.1 to 2 times the OEL

Requirement deviating from EN 482:
0.2 AC to 2 times the TC		 Required
Measurement uncertainty Requirement of EN 482:
0.1 to 2 times the OEL: ≤ 50%
0.1 to 2 times the OEL: ≤ 30%

Requirement deviating from EN 482:
0.2 AC to ≤ AC: ≤ 50 %
AC to 2 times the TC: ≤ 30%		 Required
The systematic measurement uncertainty is often stated only for the analytical steps of the method
Bias Information required Required
The bias is often stated only for the analytical steps of the method
Repeatability At least six independent repetitions at the three different concentrations Required
Selectivity Information required Required
Ambient conditions Where relevant, information on the influence of humidity, temperature or pressure should be available Required
Unambiguity Information required To be considered if required
OEL: occupational exposure limit
AC: acceptable concentration
TC: tolerable concentration

Downranking of methods

Even methods from recognized sources may fail to meet all the requirements of EN 482. For example, the IFA method descriptions are generally very short and do not satisfy the requirement concerning the "structure of the method description"; the Métropol methods very often lack sufficient validation data. The indicative ranking for such methods can be no higher than "B". In such cases, the method list contains special formulations, as shown in Table 2.

Table 2: Criteria for downranking

Criterion Formulation Action
Method description is short, or clauses from ISO 78-2 or EN 482, Annex B are missing Brief method description Downranking to "B"

(Example: IFA method)
No validation data for the method, or data insufficient No validation data published in the method, or published insufficient Downranking to "B"

(Example: Métropol method)
The sampling system stated is not suitable for the required inhalable fraction A sampling head suitable for the inhalable fraction was not used

or

Collection head for the inhalable fraction was not used, but wall deposits were analysed		 Downranking to "B"

(Example: cassette filter holder was used)
Method could not be followed Method could not be followed Downranking to "B"

(Example: laboratory methods for gases such as CO)
Legacy methods with obsolete technology Legacy method, no longer state of the art Downranking to "B"

(Example: photometric method for ammonia)