ISO 6101-4:2014 pdf download – Rubber — Determination of metal content by atomic absorption spectrometry — Part 4: Determination of manganese content.
7 Procedure 7.1 Test portion Weigh, to the nearest 0,1 mg, approximately 1 g to 5 g of rubber product and 5 g to 10 g of raw rubber, milled or finely cut into an appropriate crucible. Wrap the sample in an ashless filter paper and place into an appropriate crucible (5.11 or 5.12). The size of the test portion shall be judged by prior knowledge of the approximate amount of manganese present. 7.2 Preparation of test solution 7.2.1 Destruction of organic matter Ash the test portion in accordance with method A of ISO 247, in the muffle furnace (5.3), maintained at 550 °C ± 25 °C. If the ash is black, caused by small amounts of carbon black, stir carefully with the platinum or borosilicate-glass rod (5.10) and continue heating. 7.2.2 Dissolution of inorganic residue using hydrochloric acid After ashing, allow the crucible and its contents to cool to ambient temperature. Add 20 cm 3 of concentrated hydrochloric acid (4.1). Heat the mixture on the steam bath (5.9) for at least 10 min. Do not let the reaction mixture boil. Allow to cool to ambient temperature and transfer the solution quantitatively, with the aid of water, to a 50 cm 3 one-mark volumetric flask (5.5). If the ash is not totally dissolved, proceed as follows. Transfer the solution and the undissolved ash quantitatively, with the aid of water, to a platinum crucible (5.10). Add a few drops of concentrated sulfuric acid (4.3) and 5 cm 3 of hydrofluoric acid (4.5). Heat on the electric hotplate or heated sand bath (5.8) in a fume cupboard and evaporate until dry while stirring with a platinum rod (5.10). Repeat this digestion with the same quantities of sulfuric and hydrofluoric acids two more times. Allow to cool to ambient temperature, add 20 cm 3 of concentrated hydrochloric acid (4.1), heat for 10 min and transfer quantitatively, with the aid of water, to a 50 cm 3 one-mark volumetric flask (5.5).