Fat and oil derivates

BS EN 14104:2021 pdf free.Fat and oil derivates一Fatty acid methyl ester (FAM E) – Determination of acid value.
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2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN ISO 661, Animal and vegetable fats and oils – Preparation of test sample (iSO 661)
EN ISO 3696, Water for analytical laboratory use Specification and test methods (ISO 3696)
For the purposes of this document, the following terms and definitions apply.
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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 document
Note ito entry: The acid value is expressed in milligrams of potassium hydroxide per gram of sample.
Note 2 to entry: If the sample contains mineral acids these are determined as a part of total acid value. This method does not allow distinguishing between weak (from free fatty acids) and strong (from mineral acids, if present) acidity.
4 Principle
A test portion is dissolved in a suitable solvent mixture and titrated with a standardized solution of potassium hydroxide, using phenolphthalein as an indicator in order to detect the titration end point.
5 Reagents Use only reagents of recognized analytical grade and water of grade 3 in accordance with EN ISO 3696.
5.1 Toluene.
5.2 Isopropanol.
5.3 Solvent A for solvent mixture (5.5), ethanol, 95 % (V/V)- 97 % (V/V) purity.
5.4 Solvent B for solvent mixture (5.5), diethyl ether, peroxide free, stabilized with butylated hydroxytoluene (BHT).
5.5 Solvent mixture, mixture of equal volumes of solvent A (5.3) and solvent 8 (5.4).
Neutralize, just before use, by adding the potassium hydroxide solution (5.8) in the presence of 0,3 ml of phenolphthalein alcoholic solution (5.9) per 100 ml of solvent mixture.
If it is not possible to use diethyl ether, a mixed solvent may be used as follows:
— toluene (5.1) and ethanol (5.3), 1 + I mixture by volume;
— toluene (5.1) and isopropanol (5.2), 1 + I mixture by volume;
The mixed solvent can be replaced by isopropanol (5.2).
NOTE Larger volumes of solvent mixture and indicator can be necessary for dark-coloured samples.
5.6 Potassium hydrogen phthalate, (“99,5 %) maintained 2 h in an oven at 120 °C and cooled down in a desiccator before use, primary standard quality.
5.7 Benzoic acid, (>99,5%) to be dried before use by careful fusion in a platinum crucible at approximately 130 °C, then powdered in a mortar. Store in a desiccator until use, primary standard quality.
5.8 Potassium hydroxide, standard volumetric solution in ethanol. c(KOl-1) = 0,1 mol/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 during titration.
Isopropanol can be used instead of ethanol.
5.8.1 Preparation of the solution
Dissolve approximately 6,6 g of potassium hydroxide pellets in ethanol and dilute to 1 000 ml with the same solvent.
The same procedure can be followed when water instead alcohol is used.
Use solution prepared at least 5 days previously and decanted into a brown glass bottle, fitted with a rubber stopper. The solution shall be colourless or straw yellow. If the bottle is connected to the burette, provision shall be made to prevent intake of carbon dioxide, for example by using a tube filled with granular soda lime.
Weigh, to the nearest 0,000 1 g. approx.. 180 mg of potassium hydrogen phthalate (5.6) or approximately 100mg of benzoic acid (5.7), in a 300 ml flask and dissolve in 100 ml of distilled water. Carry out titration using KOH 0,1 molfl solution (alcoholic or water solution), using phenolphthalein solution (5.9) as an indicator. At the end point the colour of solution turns to a persisting pink.
Potassium hydrogen phthalate and benzoic acid dissolve slowly in water: carefully check that the sample is completely dissolved before starting the titration.
5.9 Phenolphthalein, log/I soluton in ethanol (5.3).
NOTE Phenolphthalein alcoholic solutions are commercially available and suitable for use.
6 Apparatus
6.1 Burette, 10 ml capacity, graduated in 0,02 ml subdivisions, EN ISO 385 class A (21.
6.2 Analytical balance, capable of weighing with an accuracy of ± 0,00 1 g or better.
7 Sampling
Sampling is not part of the method specified in this document. A recommended sampling method is given in EN ISO 5555 [3].
It is important that a laboratory receives a sample, which is truly representative and has not been damaged or changed during transportation and storage.
8 Preparation of the test sample
Prepare the test sample in accordance with EN ISO 661. The test sample shall not be heated and/or filtered.
9.1 Test portion
Weigh approximately 20 g (accuracy ± 0,001 g) of the test sample into a 250 ml conical flask. 9.2 Determination
9.2.1 Dissolve the test portion (9.1) in 100 ml of previously neutralized solvent mixture (5.5).
After the addition of some drops of phenolphthalein solution (5.9) start the titration whilst stirring the solution, using the potassium hydroxide solution (5.8) to the end point when the addition of a single drop produces a slight, but definite colour change persisting for at least 15 s.
An automated titration system applying optical detection to detect the end point may also be used provided it has been validated to meet the precision values specified in Clause 11.
9.2.2 If the solution becomes turbid during titration, add a sufficient quantity of the mixed solvent (5.5) to give a clear solution.
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 KOl-I/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 lCOH/g more than once out of 20 determinations.
The test report shall at least specify:
a) reference to this document, i.e. EN 14104:2021;
b] the result (see Clause 10];
c) any deviations from the procedure;
d) any unusual features observed;
e) the date of the test.BS EN 14104 pdf free download.Fat and oil derivates