Calculate assay of lisinopril dihydrate based on the anhydrous form - How to
March 20, 2013
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Date: 20-MARCH-2013 Last Updated: 11-OCTOBER-2025
Correcting for Water Content in Reference Standards: Lisinopril Example
Correcting for Water Content in Reference Standards: Lisinopril Example
When using a reference standard in assay calculations—such as for a formulation containing lisinopril—it's essential to account for water content if the standard is in a hydrated form, such as the dihydrate.
To ensure accurate results, apply a mass correction factor based on the molecular weights:
Correction Factor = MW of anhydrous lisinopril / MW of lisinopril dihydrate
This adjustment allows you to calculate the true mass of anhydrous lisinopril present in the portion of the reference standard you weighed. Without this correction, your assay results may overestimate the active content due to the additional mass contributed by water molecules.