Reference: BP/USP
Determination of Loss on Ignition: Loss on ignition is the loss in weight in % 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 mortar and pestle.
As per BP:
- Weigh a silica or platinum crucible, complete with the lid, previously ignited for 1 hour at the temperature specified for the test 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, & 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 & 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 & allow it to cool in a desiccator to room temperature before weighing. Use protective garments/hand gloves or safety devices & long tongs while operating at high temperatures.
As per USP:
- Perform the test on finely powdered material, and break up lumps, if necessary, with the aid of a mortar and pestle before weighing the specimen. Weigh the specimen to be tested without further treatment, unless a preliminary at a lower temperature, or other special pre-treatment, is specified in the individual monograph.
- Unless other equipment is designated in the individual monograph/specification. Unless other equipment is designated in the individual monograph, conduct the ignition in a suitable crucible, complete with cover, previously ignited in a suitable muffle furnace or oven that is capable of maintaining a temperature within 25ºC of that required for the test, and use a suitable crucible, complete with cover, previously ignition for 1 hour at the temperature specified for the test, cooled in a desiccator, and accurately weighted.
- Unless otherwise directed in the individual monograph/specification transfer to the tared crucible an accurately weighed quantity, in gm, of the substance to be tested, about equal to that calculated by the formula: 10/L In which L is the limit for loss on ignition, in percentage. Ignite the loaded uncovered crucible, and cover at the temperature (± 25°C) & for the period of time designated in the Individual monograph. Ignite for successive 1-hour periods where ignition to constant weight is Indicated.
- Upon completion of each ignition, cover the crucible, &allow it to cool in a desiccator to room temperature before weighing.
Revision History
Nil
Tags
GTP
