ISO 11723-2016 pdf download

ISO 11723-2016 pdf download.Solid mineral fuels一Determination of arsenic and selenium一Eschka’s mixture and hydride generation method. Add 10 ml of hydrochloric acid (52) to the crucible and gently warm on a hotplate. Transfer to the bottle (or beaker). Wash the crucible with a further 5 ml of water and transfer the washings to the bottle (alternatively to a beaker). Shake gently to allow the evolution of any carbon dioxide produced. WARNING — Hydrochloric acid must be added carefully as the reaction with Eschka’s mixture Is exothermic and releases carbon dioxide. Allow the bottle to cool and adjust the mass of solution to 50.0 g with water (alternatively, transfer the solution from the beaker to a 50 ml volumetric flask and make up to volume). 8.3 Preparation of calibration standards Add 1 g of Eschka’s mixture (Sd) to four tared plastic bottles (6,5) (alternatively to beakers). Add approximately 10 ml of water and 20 ml of hydrochloric acid (5.2) to dissolve the Eschka’s mixture. Allow the solutions to cool. Adjust one solution to 50,0 g (alternatively, transfer solution to 50 ml volumetric flasks and adjust one to volume with water). This is the calibration blank. To the other bottles (or flasks), add respectively, 1.00 ml, 2.00 ml and 3,00 ml ± 0,02 ml of the appropriate working standard (58) or (5JJJ. Adjust the mass of solution to 50,0 g (alternatively 50,0 ml). These calibration standards are 1 pg/kg. 2 pg/kg and 3 pg/kg of solution (or pg/I). 8.4 Preparation for measurement 8.4.1 General Solutions are pI’epa red as in UA2 and 8A3. 8.4.2 Arsenic Pipette 10 ml of each calibration standard and test solution, including blanks, of solution into separate plastic vials of capacity approximately 30 ml. Add 5 ml of hydrochloric acid (52) to each vial. Add 0,5 ml of potassium iodide solution (S4) to each vial and let stand for 20 mm. 8.4.3 Selenium Pipette 10 ml of each calibration standard and test solution, including blanks, into tall beakers or test tubes of capacity 25 ml to 50 ml. Add 5 ml of HCI. Heat at 90 °C for 15 mm to 20 mm to reduce selenite to selenium. Do not boil or heat solutions in beakers or test tubes for longer than 20 mm as selenite can be reduced to elemental selenium. The effectiveness of the reduction process can be assessed by ‘reducing a calibration standard of sodium selenate...