DIN EN 14104 pdf free download
DIN EN 14104 pdf free download. Fatty acid methyl esters (FAME).
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments).
EN ISO 661, Animal and vegetable fats and oils – Preparation of test sample (ISO 661:1989).
EN ISO 3696, Water for analytical laboratory use – Specification and test methods (ISO 3696:1987).
3 Terms and definitions
For the purposes of this European Standard, the following term and definition apply.
3.1
acid value
number of milligrams of potassium hydroxide required to neutralise the free fatty acids present in 1 g of FAME, when determined in accordance with the procedure specified in this European Standard
Acid value is expressed in milligrams of potassium hydroxide per gram of sample.
NOTE If the sample contains mineral acids these are, by convention determined as a part of total acid value. This method
does not allow to distinguish between weak (from free fatty acids) and strong (from mineral acids, if present) acidity.
4 Principle
A test portion is dissolved in a mixed solvent and titrated with a diluted solution of potassium hydroxide, using
phenolphthalein as an indicator in order to detect the titration end point.
5 Reagents
Use only reagents of recognised analytical grade and water of grade 3 in accordance with EN ISO 3696.
5.1 Diethyl ether and 95 % ethanol, 1 + 1 mixture by volume.
WARNING Diethyl ether is very flammable and may form explosive peroxides. Use with great caution.
Neutralise, just before use, by adding the potassium hydroxide solution (5.2) in the presence of 0,3 ml of phenolphthalein alcoholic solution (5.3) per 100 ml of solvent mixture.
If it is not possible to use diethyl ether, a mixed solvent may be used as follows:
— toluene and 95 % (V/V) ethanol, 1 + 1 mixture by volume;
— toluene and 99 % (V/V) 2-propanol, 1 + 1 mixture by volume. The mixed solvent can be replaced by 99 % (VM) 2 propanol. NOTE Larger volumes of solvent mixture and indicator may be necessary for dark-coloured samples. 5.2 Potassium hydroxide, standard volumetric solution in ethanol: c(KOH) = 0,1mol/l The ethanolic potassium hydroxide solution can be replaced by aqueous potassium or sodium hydroxide solutions, but only if the volume of water introduced does not lead to phase separation. 5.2.1 Preparation。 f th solution Dissolve approximately 7 g of potassium hydroxide pellets in ethanol and dilute to 1 000 ml with the same solvent. NOTE 2 propanol can be used instead of ethanol. Weigh, to the nearest 0,0002 g, 0,15 g of benzoic acid having minimum purity 99,9 % (m/m), or another primary standard, in a 150 ml beaker and dissolve in 50 ml of 4-methylpentan-2-one (5. 4). Use a pH meter to follow titration and to detect the end point, start the stirrer and titrate with the potassium hydroxide solution to the equivalence point.11 Precision 11.1 Interlaboratory test Details of interlaboratory test are given in annex A. The values derived from these tests may not be applicable to concentration ranges and matrices other than those given. 11.2 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 interval of time, shall not be greater than 0,02 mg KOH/g more than once out of 20 determinations. 11.3 Reproducibility The absolute difference between two single test results, obtained using the same method on identical test material in different laboratories with different operators using different equipment, shall not be greater than 0,06 mg KOH/g more than once out of 20 determinations.DIN EN 14104 pdf download.
