BS ISO 5647:2019 pdf download – Paper and board — Determination of titanium dioxide content

BS ISO 5647:2019 pdf download – Paper and board — Determination of titanium dioxide content 7 Selection of the sample Select a representative sample in accordance with ISO 186. Tear the air-dry sample into pieces of suitable size. Use protective cotton gloves. Do not use cut or punched edges or other parts where metallic contamination may have occurred. 8 Preparation of ash solution 8.1 Carry out the determination in duplicate. Weigh, to the nearest 0,01 g, two test portions of about 10 g of paper or board and place each test portion in a clean dish (6.1). Determine the moisture content of a separate test sample as prescribed in ISO 287. NOTE Select the amount of sample to be ashed, taking into account the anticipated titanium dioxide content. If a 10 g portion is ashed, the optimum range of the titanium dioxide content is from 1,5 g/kg to 8 g/kg (spectrophotometric procedure) or from 0,8 g/kg to 3,2 g/kg (flame atomic absorption spectrophotometric procedure). 8.2 Ash the test portion as described in ISO 2144. Allow the dish to cool in a desiccator. If the ash content of the sample is of interest, weigh the dish with its contents and calculate the amount of ash obtained. 8.3 Transfer the ash to a 250 ml glass beaker. Add 4 g of ammonium sulphate (5.3) and 10 ml of the sulphuric acid (5.2). Mix well and cover the beaker with a watch glass. Heat in a fume hood until fumes of sulphur trioxide are evolved and continue heating for 30 min. Allow the solution to cool to room temperature and then carefully add it, drop by drop, to about 50 ml of water contained in another beaker. Allow the solution to cool and decant it into a 100 ml volumetric flask. Rinse both beakers with water and add the rinsings to the flask. Finally, make up to the mark with water and mix well. 9 Reagent blank solution Prepare a reagent blank solution, using 4 g of ammonium sulphate (5.3) and 10 ml of sulphuric acid (5.2) in a glass beaker, as described in 8.3. 10 Spectrophotometric procedure 10.1 Preparation of the calibration graph Into one of a series of six 50 ml volumetric flasks, place 25,0 ml of the reagent blank solution (Clause 9). Into the remaining five 50 ml volumetric flasks, transfer the quantities of the standard titanium dioxide solution (5.5),...