Forced Degradation Mass Balance Calculator

Check that assay loss is accounted for by the degradants you can see.

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Initial assay %

Initial total impurities %

Stressed assay %

Stressed total impurities %

Example: an oxidative stress sample.

Mass balance–

Degradation–

Unaccounted–

Mass balance % = (assay_stressed + impurities_stressed)/(assay_initial + impurities_initial)·100

How it works

Mass balance is the sum of the remaining API and the measured degradation products, compared with the starting value. ICH Q1A(R2) describes it as a check that the method can see what the API turns into, which supports the claim that it is stability-indicating.

A shortfall usually means a degradant is missing: retained on the column, eluted in the void, lacking a chromophore at the chosen wavelength, volatile, or quantified with the wrong response factor. A PDA or MS detector helps find it.