background image
Note for Guidance for Food Contact Materials
Page 102 of 126
the result of the determination shall be confirmed. The confirmation is qualitative in the
sense that it should demonstrate the correct identity of the measured analyte and the
absence of interferences. For the purposes of quantitation the result as calculated
according to Section 6.5 shall be taken as the true value.


Method performance has been evaluated by carrying out a precision experiment
according to ISO 5725-1990 'Accuracy (Trueness and Precision) of Measurement
Methods and Results', Parts 1-6.

8.1 Validation
(N.B. For the applicant this item may be omitted).
For validation of this method a precision experiment was conducted in [YEAR],
involving [NUMBER] laboratories. Each participant in this experiment obtained
[NUMBER] samples of [ANALYTE]-free [MATRIX] together with sets of [NUMBER]
samples of [MATRIX] fortified with [ANALYTE] at levels of approx. [LEVEL]
[MASS]/kg respectively.
Calibration solutions were prepared with comparable concentrations so that the
calibration samples could be corrected.

8.2 Repeatability
Evaluation of the results of the precision experiment at a concentration of [LEVEL]
[MASS] [ANALYTE]/kg [MATRIX] for the 95% probability level yielded the following
performance characteristics:

Repeatability: r = [LEVEL][MASS][ANALYTE]/kg

(N.B. For the
applicant this
item may be omitted).
There was no influence of the calibration method using [STANDARD] on the numerical
values of r and R.

8.3 [LIMIT]
The [LIMIT] of [ANALYTE] - measured as equal to the mean content of representative
[BLANK] (n _ 20) plus three times the standard deviation of the mean - was found to be
in the range of [RANGE] [MASS] [ANALYTE]/kg [MATRIX].
Thus the method is capable of quantitative determination of [ANALYTE] at a minimum
level of [LEVEL] [MASS]/kg [MATRIX].

Critical [ANALYTE] level
The question whether there is a significant difference for the 95% probability level
between the restriction for [ANALYTE] - i.e. [RESTRICTION] - and [SML or QM],
calculated from the analyte concentration in [MATRIX] determined by this method, can
be decided by means of the critical difference CrD95.