BS ISO 6588-2-2012 pdf download.Paper, board and pulps Determination of pH of aqueous extracts Part 2: Hot extraction. 4.1 Water, distilled or deionised water shall be used throughout the test. The conductivity of the water shall not exceed 0,1 mS/rn after boiling for 1 h and cooling in an acid-free atmosphere (e.g. free of C02, SO2, H2S) to a temperature between 20 °C and 25 °C. The pH of the water should be in the range of 6,8 to 7,3. Instructions for the determination olconductivity are specilled in ISO 3696. 4.2 Standard buffer solutions, with known pH-values of about 4, 7 and 9. Such buffer solutions are commercially available. Some examples of suitable buffer solutions are given, and their preparation is described, in Annex A. 4.3 Potassium chloride solution, 1 M. Dissolve 7,4 g of XCI, analytical grade, in 100 ml of freshly boiled, distilled water. Prepare a fresh solution every week. 5 Apparatus and equipment Use the following, in addition to ordinary laboratory apparatus and equipment. 5.1 Glassware of chemically resistant glass, flasks with ground-glass joints, stoppers, beakers, reflux condenser and fritted glass filter. All glassware shall be cleaned with an acid cleaning solution, without the use of soap or detergent, and they shall be carefully rinsed with water (4.1) and allowed to dry before use. 5.2 pH-meter, fitted with glass and calomel electrodes or with a combined electrode, capable of being read to at least 0,05 pH-unit. 6 Sampling and preparation of sample 6.1 Sampling The sampling procedure to be followed depends on the particular circumstances in each case. lithe analysis is being made to evaluate a lot or a consignment of pulp, paper or board, the sample shall be taken in accordance with ISO 7213 or ISO 186, as relevant, lithe analysis is made on another type of sample, report the origin of the sample and, if possible, the sampling procedure, and ensure that the specimen taken in 7.1 is representative of the sample received. Wear clean protective gloves when handling the sample. NOTE Some gloves are powdered to prevent them from sticking to one another, and this powder can cause contamination of the sample. 6.2 Preparation of sample Do not touch the sample with bare hands and ensure that it has been placed only on clean surfaces. Cut or tear the sample into pieces approximately 1 cm2 in size with a clean knife or a cutter....
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