By Anonymous on Saturday, January 18, 2003 - 10:26 pm:
Does anyone know whether there are any references available in performing a method validation for an active drug substance (API), using the USP Karl Fischer method ?
By Anonymous on Sunday, January 19, 2003 - 08:10 am:
Can you explain in detail ?
By labcat on Sunday, January 19, 2003 - 11:54 pm:
It's not about the USP method, but I found it very useful:
"A validation procedure for the semi-micro determination of water"
Pharmeuropa, 1999, 11, 578-585
By Anonymous #3 on Monday, January 20, 2003 - 08:28 am:
Personally, I don't exactly understand the initial question: KF is specific for water, not an active drug substance, so why does any such KF test need to be validated???
By Anonymous on Tuesday, January 21, 2003 - 05:41 am:
Karl Fischer titration is not infallible. There are pitfalls. Yes, the test should be validated - shown to give true results under the conditions and limits claimed. Does the substance dissolve in the titrant solution? Is all bound water released? Are there impurities in the substance or will the substance itself interfer with the endpoint of the titration? Do you get excellent recoveries when water is added to the substance?
Since purity is an issue here try to confirm the amount of water by Loss on Drying and Thermal analysis of the substance to back up your KF method analysis.
By Anonymous on Tuesday, January 21, 2003 - 01:58 pm:
The expert for Karl Fisher is Helga Hoffman at Sigma Aldrich (Riedel-de Haen Reagents)Germany ... but I lost her e-mail address !!!
The reference etc. you will need she can get for you.