Title: Determination of Loss on Ignition
1. Objective: Determination of loss on Ignition of Powder.
2. Principle: 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
3. Procedure:
3.1 Loss on ignition: (LOI)
Weigh a silica or platinum crucible, complete with the lid, previously ignited for 1 hour at 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 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.
Calculation:
Weight of empty Crucible with lid: W1
Weight of empty Crucible with lid + sample: W2
Weight of sample: W3= (W2 – W1)
Weight of Crucible with lid + sample (After ignition): W4
Weight Loss: W5 = (W2 – W4)
% Loss on ignition = W5 x 100
W3