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Description
INTRODUCTION:
The test determines the amount of volatile matter of any kind (including water) that can be driven off under the conditions specified. The test is carried out on a well mixed sample of the substance. If the substance is in the form of large crystals, reduce the size to about 2 mm by rapid crushing to a powder.
PROCEDURE:
Dry clean glass-stoppered, shallow weighing bottle at temperature for 30 minutes under the same conditions at which the determination is to be carried out. Cool to room temperature (about 30minutes) in a desiccator and take the weight accurately (W1g)
If the test sample is in the form of large crystals, reduce the particle size by quickly crushing.
Tare a glass stoppered shallow weighing bottle and transfer to the bottle about
1 to 2 g of the sample unless otherwise specified in the individual test procedure,close it and accurately weigh (W2 ).
By gentle sidewise shaking distribute the test specimen as evenly as practicable to a depth of about 5mm.
If the specimen under test is capsules, use a portion of the mixed contents of not less than four capsules.
If the specimen under test is Tablets, use powder from not less than four tablets ground to a fine powder
Place the loaded bottle in the oven, by removing the stopper. Dry the sample to constant weight or for the specified time, and at the temperature indicated in the individual test procedure.
The temperature of drying specified should not vary by more than ± 2°C.
Open the oven, close the bottle promptly. Place it in a suitable desiccator, allow it to cool to room temperature and take the weight accurately (W3 g).
(W2 g - W3 g) x 100
% Loss on Drying = ---------------------------------
(W2 g - W1 g)
(10) Drying conditions:
a) Desiccator : Over phosphorus pentoxide at room temperature and atmospheric
pressure in a desiccator.
b) In vacuo at... : Over phosphorus pentoxide at a pressure 1.5 to 2.5 KPa*** in a
room temperature and at the specified temperature.
c) In vacuo : In an oven at a pressure 1.5 to 2.5 KPa*** in a vacuum desiccator
at room temperature.
d) ***Under high vacuum: The drying is carried out over phosphorous pentoxide at a
pressure 0.1kPa at the temperature specified.
e) At specified temperature and time: In a oven set at the specified temperature and for the
time indicated or to constant weight*, where time is not
specified.
*- Constant weight means that two consecutive weights which do not differ by more than
0.5 mg per g of the substance.
***- As per Ph.Eur.
Note: Where drying in a desiccator is specified, care must be taken to keep the desiccant fully effective by frequent replacement.
Tags
Loss on drying, large crystals, accurately weigh, suitable desiccator
