Assay and Repeatability Calculator
Calculate mg per unit and % of label claim for every sample from its own weight, with the mean and repeatability %RSD for method validation.
- ICH Q2(R2) repeatability
- Each sample weight
- mg/unit and % LC
- No sign-up
Four steps, or fewer
- Enter the standard preparation and paste its replicate responses.
- Enter the sample dilution volume, average unit weight and label claim.
- Paste each sample’s weight and response. Use the actual weight of each preparation.
- Check mean assay and %RSD against your limits, then print the report.
Not sure what to enter? Press Load example to see the calculator with realistic data. Your inputs are saved in this browser, so they are still there when you come back.
How the assay is calculated
Each sample is compared with the mean standard response. Using each preparation’s own weight avoids a common spreadsheet error where one weight is copied down the column.
mg/unit = (A_spl / Ā_std) × C_std × DF_spl × average weight / W_spl
% label claim = mg/unit / label claim × 100
Repeatability (ICH Q2(R2))
Repeatability is assessed with at least six determinations at 100% of the test concentration, or nine determinations covering the range (three levels, three replicates each). A %RSD of ≤ 2.0% is a common acceptance criterion for drug product assays.
References
- ICH Q2(R2) Validation of analytical procedures
- USP General Chapter <1225>
These calculators are decision support for orientation and training. They are not validated GMP software, and results must be checked against your approved method, SOP and the current pharmacopoeia or guideline before use in GMP records. Your data is processed in your browser and is not sent to Molgenium.