Chromatography Forum

Dear All,

The loss on drying for the above subject is not mention in EP. Suppose if we perform this test, what should be the maximum allowed limit. (perform at 105°C) for three hours

Please note that the water content is between 5.9 to 6.9%.

Please provide the calculation......
Regds

If the water content is between 5.9 to 6.9 % - that would be a good start on whaty you would expect for loss. However, be careful. Some compunds bind water tightly and the water can not be removed easily at low temperature. In other compunds, thermal degredation can result in loss - of part of the molecule. This one may be worth a bit of library work.

Hi

Agree with Don here, can be a bunch of pitfalls. First I really do not see a point with doing loss of drying at all if the monograph contains a Karl Fisher water content requirement. Loss of drying with regard to residual class 3 solvents is not doeble due to water content >0,5%.
So whats the purpose of the test in first place?

Generally I would do a series of test to find a suiteble initial drying time, like 2-3-4 hours, then to constant weight and in parallell test water content by KF and residual solvents to see if LoD match combined KF and residual solvent result. I recently had a similar discussion with a regulatory laboratory that had run a too short initial drying time and consequently got out of specification results.

Choice of temperature and technique (vaccum lower temp instead?.....etc) requires some litterature studies to predict whats suiteble as Don stated, your chemists should have acess to a bunch of solid phase data/physical properties.

Dear All,

Thanks for the valuable info...........