The moisture content of a powder is the loss in weight (%) after oven drying at 102oC untill constant weight is obtained.
The sample is dryed by oven drying to constant weight at 102oC ± 2oC for 4 hours. The oven drying is repeated untill the two successive weighing do not differ more than 0.5mg.
- International IDF Standard 26A:1993
- FAO FNP 14/7, p.205-1986 – Determination moisture content
- Drying oven, with thermostat and without forced air circulation.
- Analytical balance, sensibility ± 0.001g.
- Desiccator with colour-indicating desiccant.
- Weighing dishes with lid.
- Dry weighing dish with open lid in the oven, and cool it in desiccator.
- Weigh the empty dish (mo), add approx. 2.5g ± 0.5g of powder and weigh again (m1).
- Place the loaded dish with open lid in the oven at 102oC ± 2oC for 2 hours.
- Cool closed dish to temperature in desiccator, and wiegh (m2)
- Continue drying the loaded dish with open lid the oven at 102oC ± 2oC for 1 hour.
- Repeat the cooling 5.4 and weigh again (m2)
- Repeat 5.5 and 5.6 until two succesive weighings differ less than 0.5mg
m0: weight of empty dish (g)
m1: weight of dish + powder (g)
m2: weight of dish + dried powder (g)