Chromatography Forum

I stressed sugary sample at (50C, 75% RH), the assay value using assay method 60% and impurities using related compounds method accounted for 19% impurities (RRF used), the mass balance is 60+19 =79%. Ran KF and found 10% moisture in the stressed sample. How to calculate mass balance based on 10% moisture? Is the moisture apply to assay or both (assay & impurity)? Any additional advice will be appreciated

Thanks

Don't you just need to show that your compound of interest is the same, and that any degradation products don't interfere with its chromatography?

I want to see if I can simulate stability in commercial product, when I ran the stability sample got 30% degradation and mass balance 100.3% but my mass balance in stressed sample did not add up.

There is an excellent book by Steven Baertschi on forced degradation, I strongly recommend obtaining a copy. I think it will answer your Qs.

I checked this book at Amazon and saw table of contents, it looks like a great book, I will order it.Thanks for recommendation.

I stressed sugary sample at (50C, 75% RH), the assay value using assay method 60% and impurities using related compounds method accounted for 19% impurities (RRF used), the mass balance is 60+19 =79%. Ran KF and found 10% moisture in the stressed sample. How to calculate mass balance based on 10% moisture? Is the moisture apply to assay or both (assay & impurity)? Any additional advice will be appreciated

Thanks

To answer your original post: you found 10% moisture in your sample, so assuming that you need 100mg sample, you weighted 90mg sample and 10 mg water.

So your need to do a correction for all your values, so 79% * 100/(100-10%) = 87.8% instead of 79%

Ace