ISO 17072-2-2019 pdf free.Leather – Chemical determination of metal content – Part 2: Total metal content. Weigh accurately 1 g of the prepared leather to the nearest 0,001 g using an analytical balance (3) and place in a long-necked Kjeldahl digestion flask (6i). Add, using a measuring cylinder, 10 ml to 20 ml of a ternary mixture of nitric acid (&Z). sulfuric acid (5.3) and perchloric acid (SA) in a ratio of 3:1:1, and a few glass boiling beads (69). Place a funnel or splash bulb in the neck of the flask and heat to boiling. Leave to react on the heating apparatus (6A) until digestion is complete and the red vapours of nitrogen dioxide have disappeared. Stop warming after digestion is complete. In the event of incomplete digestion, allow the flask to cool, add a further 10 ml to 20 ml of the ternary acid mixture and repeat the procedure. For lead (Pb) determination, the digestion procedure shall be carried out separately, replacing sulfuric acid (5.3) with hydrochloric acid (5.6). In the case of high volatile metals determination, check that this open acid digestion doesn’t cause a partial loss of these elements. WARNING — It is imperative that the…