Chromatography Forum

Hi,

Not sure if this is appropriate to post a titration related issue, but I still hope that people could give me some suggestions in relation to my karl fischer problem.

We have Metrohm volumetric KF titration system. Recently I found that the titer value is getting lower in the past 2 or 3 months. The titer range value should be 4.5 to 5.5mg/ml according to the Fluka titer bottle. The value I got from calibration decreased from 5.1 mg/ml in December 2014 to 4.55 mg/ml in March 2015, and this is about the time I started to get worried.

Does that mean that water has been trapped into the KF system?

Hope the problem can be solved soon, thanks very much everyone!

Deerlu

Probably should go in the Around the Water Cooler section, and no pun intended.

I would say that your titrant is absorbing moisture from the atmosphere, so becoming lower in titer. I couldn't tell for sure if you were using a "water standard made up in methanol" or simply standardizing v. liquid water, like weighing 80 mg water and titrating.

Hi deerlu

Yes probably your equipment (KF reagent bottle included) is absorbing water somewhere, get it cheked by de vendor.
In the meantime every day you have to perform titration standarize the reagent at least 3 times average and use that value.

Fernando.

Hi both,

Thanks for the advices, maybe I will replace the molecular sieve, the solvent and the titer if necessary. Hope it can get back to what it was soon.

Thanks again!