7 Expression of results
7.1 Determination of ester content
The ester C content, expressed as a mass percentage, is calculated using the following equation:
where
ΣA is the total peak area from the methyl ester in C6:0 to that in C24:1;
AEI is the peak area corresponding to nonadecanoic acid methyl ester;
WEI is the weight, in milligrams, of the nonadecanoic acid methyl ester being used as internal standard;
W is the weight, in milligrams, of the sample.
NOTE 1 In the case of vegetable oils, the result of the calculation based on relative areas is considered to represent a percentage by mass.
NOTE 2 If the average of two determinations is higher than 100 % then discard the results and verify the experimental conditions as well as the purity of the internal standard by using this method to determine the ester content of a commercial or prepared mixture, and the water content of the internal standard by Karl Fischer determination.
7.2 Determination of linolenic acid methyl ester
The linolenic acid methyl ester content L, expressed as a mass percentage, is calculated using the following equation:
where
AL is the peak area corresponding to linolenic acid methyl ester;
AEI is the peak area corresponding to nonadecanoic acid methyl ester;
WEI is the weight, in milligrams, of the nonadecanoic acid methyl ester being used as internal standard;
W is the weight, in milligrams, of the sample.
7.3 Expression of results
Ester content and linolenic acid methyl ester content are expressed in percentage (m/m), to the nearest 0.1 %.
8 Precision
8.1 Interlaboratory test
An interlaboratory test organized in 2009 at European level with the participation of 18 laboratories, each having carried out two determinations on each sample, gave the statistical results indicated in Annex B.
8.2 Repeatability
The absolute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short time interval, shall not be greater more than once out of 20 determinations than the values given in Table 1:
8.3 Reproducibility
The absolute difference between two single test results, obtained using the same method on identical test material in different laboratories by different operators using different equipment, shall not be greater more than once out of 20 determinations than the values given in Table 2:
9 Test report
The test report shall specify:
- all information necessary for the complete identification of the sample;
- the sampling method used if known;
- the test method used, with reference to this European Standard;
- all operating details not specified in this European Standard, or regarded as optional, together with details of any incidents which may have influenced the test result(s);
- the test result(s) obtained, or if the repeatability has been checked, the final quoted result obtained.