Loss on ignition is the loss in weight in per cent w/w resulting from a part of any test material, that is volatilized and driven off under specified conditions. The test is performed on finely powdered material; lumps, if any should be broken up with the aid of a mortar and pestle.
Weigh a silica or platinum crucible, complete with the lid, previously ignited for 1 hour at 800°C and cooled in a desiccator. Transfer to the crucible the quantity of the substance specified in the individual monograph, without any treatment, unless a preliminary drying at a lower temperature, or other special treatment is specified.
Weigh accurately the crucible, lid and the contents. Place the loaded uncovered crucible and cover in a suitable muffle furnace or oven that is capable of maintaining a temperature within 25°C of that required for the test. Ignite the crucible for the period of time and at the temperature stated in the monograph. Ignite for successive 1-hour periods where ignition to constant weight is indicated. Upon the completion of each ignition, cover the crucible and allow it to cool in a desiccator to room temperature before weighing.
Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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