ANNEX II
In point 3. ‘Method of analysis to be used by the laboratory and laboratory control requirements’, the following point 3.3.3. is inserted after Table 4:
‘3.3.3.Performance Criteria — Uncertainty Function Approach
However, an uncertainty approach may also be used to assess the suitability of the method of analysis to be used by the laboratory. The laboratory may use a method which will produce results within a maximum standard uncertainty. The maximum standard uncertainty can be calculated using the following formula:
where:
Uf is the maximum standard uncertainty
LOD is the limit of detection of the method
C is the concentration of interest
α is a numeric factor to be used depending on the value of C. The values to be used are given in the table below:
| C (μg/kg) | α |
|---|---|
| ≤ 50 | 0,2 |
| 51-500 | 0,18 |
| 501-1 000 | 0,15 |
| 1 001-10 000 | 0,12 |
| ≥ 10 000 | 0,1 |
and U is the expanded uncertainty, using a coverage factor of 2 which gives a level of confidence of approximately 95 %.
If an analytical method provides results with uncertainty measurements less than the maximum standard uncertainty the method will be equally suitable to one which meets the performance characteristics given above.’
Point 3.4. is replaced by the following:
‘3.4.Estimation of the analytical trueness, recovery calculations and reporting of results
Wherever possible the trueness of analysis shall be estimated by including suitable certified reference materials in the analysis.
The analytical result is to be reported corrected or uncorrected for recovery. The manner of reporting and the level of recovery must be reported.
The analyst should note the “European Commission Report on the relationship between analytical results, the measurement of uncertainty, recovery factors and the provisions in EU food legislation”(1).
The analytical result has to be reported as x +/– U whereby x is the analytical result and U is the measurement uncertainty.
REFERENCES
(1)European Commission Report on the relationship between analytical results, the measurement of uncertainty, recovery factors and the provisions in EU food legislation, 2004
(http://europa.eu.int/comm/food/food/chemicalsafety/contaminants/sampling_en.htm).’