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ISO 660-2009 pdf free download

ISO 660-2009 pdf free download.Animal and vegetable fats and oils Determination of acid value and acidity
Corps gras d’origines animale ef vegetale — Determination de I’m dice d’acide et de I’acidité.
9.2 Cold solvent method using potentiometric titration (Reference method)
9.2.1 According to Table 1. weigh the test portion into a 150 ml beaker,
9.2.2 Add 50 ml to 100 ml of the neutralized solvent mixture (5,3) and dissolve the sample, if necessary with gentle warming.
For high melting point samples, use an ethanol-toluene mixture.
9.2.3 Introduce the combined electrode in the solvent mixture and connect it with the automatic titration apparatus.
9.2.4 Start the stirrer for at least 30 s and then titrate with constant swirling using standard potassium hydroxide solution (5.5).
9.2.5 As soon as the equivalence point is reached, record the amount of standard solution used.
9.3 Hot ethanol method using Indicator
9.3.1 Under the conditions specified in this method, short-chain fatty acids, if present, are volatile.
9.3.2 Weigh into a flask a sufficient mass of the test sample as shown in Table 1. according to the colour and expected acid value.
9.3.3 Heat to boiling 50 ml of the ethanol containing 0,5 ml of the phenolphthalein Indicator in a second flask. While the temperature of the ethanol is still above 70 °C, neutralize it carefully with a solution of 0,1 mol)l sodium or potassium hydroxide.
The endpoint of the titration is reached when the addition of a single drop of alkali produces a slight but definite colour change persisting for at least 15 s.
Larger volumes of ethanol and indicator may be necessary for dark-coloured fats. Moreover, for dark-coloured fats, alkali blue or thymolphthalein shall be used.
9.3.4 Add the neutralized ethanol to the test portion in the first flask and mix thoroughly. Bring the contents to the boil and titrate with the sodium or potassium hydroxide solution, agitating the flask contents vigorously during the titration.
11 Precision
Details of interlaboratory tests are given in Annex A. The values derived from these tests may not be
applicable to concentration ranges and matrices other than those given.
11.1 Repeatability
The absolute difference between two independent single test results, obtained with 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 in not more than 5 % of cases exceed the values given in Tables A.1 to A.3.
11.2 Reproducibility
The absolute difference between two single test results, obtained with the same method on identical test material in different laboratories by different operators using different equipment, shall in not more than 5 % of cases exceed the values given in Tables A.1 to A.3.
12 Test report
The test report shall contain at least the following information:
a) all information necessary for the complete identification of the sample:
b) a reference to this International Standard:
c) the result obtained, indicating clearly the method of expression used:
d) any operating conditions not specified in this International Standard, or regarded as optional.ISO 660-2009 pdf free download.

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