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Karl Fischer; coulometric vs volumetric

Posted: Wed Jan 02, 2019 5:02 pm
by MestizoJoe
Hi,

I was wondering when one might want to avoid coulometric. I might get a coulometric titrator because it is sensitive and requires less sample. Right now I'm only considering one drug (very water soluble).

In the future I may need to determine water in other drugs. I want to verify the versatility of the coulometric titrator.

Thanks!

Re: Karl Fischer; coulometric vs volumetric

Posted: Fri Jan 04, 2019 1:36 pm
by Consumer Products Guy
We always used volumetric KF in our labs. This would work for samples 85% water down to below 0.1%.

Re: Karl Fischer; coulometric vs volumetric

Posted: Fri Jan 11, 2019 11:28 am
by Markus Laeubli, Metrohm
Dear MestizoJoe

Volumetric KF has a higher detection limit than coulometric.
As long as your water content is high enough, volumetric is OK. But as soon as you need to go lower coulometric KF gives much more accurate results.

Re: Karl Fischer; coulometric vs volumetric

Posted: Fri Jan 11, 2019 3:37 pm
by MestizoJoe
Thank you both.

Dr. Laeubli, do you know if the paper printouts from the KF instruments from Metrohm print out the complete record? That is, does 21 CFR Part 11 have to apply to data generated by these instruments?

Re: Karl Fischer; coulometric vs volumetric

Posted: Mon Jan 14, 2019 7:02 am
by Markus Laeubli, Metrohm
Dear MestizoJo

This might depend from the instrument type.
Please check with your Metrohm subsidary or post the used models for a check.