DS-413-A Determination of pH in an aqueous extract

Codification
DECATHLON STANDARD
Document issued by TESTING LABORATORY – Decathlon Campus 4, Bd de Mons - BP 299 59665 Villeneuve d'Ascq Cedex - FRANCE
DS - 413 Version A
Others associated or required documents ISO 3696: Water for analytical laboratory use – Specification and test methods SCOPE This Decathlon Standard can be applied to textiles in any form. OBJECTIVES Determine the pH of the aqueous extract of textiles. PRINCIPLE The pH value of an aqueous extract of a textile is measured electrometrically at room temperature (20-25° C) by means of a glass electrode. The result is expressed to the nearest 0,1 pH-unit and if the difference between the pH values is more than 0,2, repeat the method. REQUIREMENTS ON EQUIPMENT & CONSUMABLES Reagents - Distilled or deionized water of at least grade 3 as defined in ISO 3696, with a pH between 5,0 and 7,0. - Potassium chloride solution (KCl), concentration of 0,1 mol.l-1, prepared by using distilled or deionized water above (find in following suppliers: VWR International, Merck…). - Buffer solutions for the calibration of the pH-meter before measurement, with a pH around 4, 7 and 9 (cf. ISO 3071: 2005 Annexe A). Equipment - Clean glassware used for that kind of test ONLY and washed every time with distilled or deionized water in between experiments: stoppered glass or propylene flasks for the preparation of the aqueous extract, 150 ml-beakers. - pH-meter, with a glass electrode, accurate to at least 0,1 pH-units. - Balance, accurate to 0,01g. - Mechanical shaker, to-and-fro movement at a rate of 60 min-1 or a rotational frequency of 30 min-1. ENVIRONMENTAL CONDITIONS The test has to be carried out at a temperature of 20-25 ° C.
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Codification
DECATHLON STANDARD
SAMPLE PREPARATION
DS-413 Version A
Before manipulating the sample, hands should be washed properly and dried. To avoid contamination, handle the material as little as possible. Take three laboratory samples of 2,00 ± 0,05 g each representative of a bulk of the textile material. Cut the samples into pieces of 5 mm sides or of such a size as to allow the test samples to wet out quickly. TEST PROTOCOL REQUIREMENTS Extraction Prepare the extract in triplicate as follows: Place 2,00 ± 0,05 g of cut samples and 100 ml of potassium chloride solution into a stoppered flask. Shake the flask for a short period by hand to ensure that the textile material is properly wet out, and then shake it mechanically for 2h ± 5 min. Record the temperature of the KCl solution used. Calibration of the pH-meter Calibrate the pH-meter at the temperature of the extract measurement by using at least two buffer solutions. Rinse the electrode with distilled or deionized water and dry it properly after the use of each buffer solution. Then immerse the electrode in the potassium chloride solution for conditioning. Measurement of the pH First, take a clean beaker and measure the pH of the potassium chloride solution. Record the pH value. Then do not rinse the electrode. Take the first flask, decant the extract and immerse immediately the electrode to a depth of at least 10 mm and stir gently until the pH value stabilizes. Do not record this pH value.
OBJECT AND SCOPE This Decathlon Standard specifies a method based on the International Standard ISO 3071: 2005 to determine the pH of the aqueous extract of all types of textile.
DECATHLON STANDARD
DS-413 Version A
COPYRIGHT WARNING All mentioned external reference standards shall be owned by the user of this document.
PURPOSE This document is an internal Test Standard. It contains the general test requirements which are applicable in all the internal or external laboratories where the tests are carried out. When stated, this document defines the useful criteria to establish the conformity of a product or a component. This document aims to harmonize choices and possible interpretations of the international test standards. This document does not contain the detailed modalities of implementation of the tests, regarding to specific test equipments and accommodations of the Laboratory. These modalities must appear in Work Instructions written locally by every laboratory.
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Codification
DECATHLON STANDARD