9. Procedure
9.1 Ignite a coded crucible to constant weight at 750°C. Record the mass to 0.1 mg.
9.2 Weigh a 10 g portion of the dried analysis sample into the coded crucible. Record the mass to 0.1 mg.
9.3 Place the crucible into a cold muffle furnace that has been tested for adequate air circulation, and heat directly to above 700°C until constant mass (+/- 0.2 mg) is obtained. Do not exceed 750°C.
9.4 Allow the furnace to cool to 150°C and transfer the crucible to the desiccator for further cooling.
9.5 Weigh the crucible and ash to the nearest 0.1 mg.
10. Calculation
10.1 Calculate the ash percent in the analysis sample as follows:
where:
A = mass of crucible and ash residue, g,
B = mass of empty crucible, g, and
C = mass of analysis sample used, g.