Assay Values in Certificate of Analysis

Last Review: June 2005

The Certificate of Analysis of a chemical will show both the assay value of that specific lot and the specified allowable range values for that assay which was established either by the official monograph or by the manufacturer of the chemical. If the assay value of that particular lot falls within the specified range, the chemical is considered to be "within the specifications" and no correction in concentration needs to be made. On the other hand, if the assay value falls out of the allowable specifications, the pharmacist must return the chemical to the manufacturer since its assay value is not acceptable, i.e., it is "out of specification".

Example:

DEXCHLORPHENIRAMINE MALEATE, USP
Description Limit (min- max) Result
Assay 98 - 100.5% 100.2%

In this case, the limits in the assay value are established by the USP and the result falls within the allowable range. Therefore, no correction is required.