Impurity Threshold Calculator
Get the ICH reporting, identification and qualification thresholds for your daily dose, then paste batch results to see which impurities to report, identify or qualify.
- ICH Q3A(R2) and Q3B(R2)
- ICH rounding
- Draft specification
- No sign-up
Four steps, or fewer
- Choose drug substance (Q3A) or drug product (Q3B) and enter the maximum daily dose.
- Paste impurity results for up to three batches.
- Each result is rounded the ICH way and classified. Use the draft specification notes as a starting point.
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 thresholds are set
Where a threshold is “a percentage or a total daily intake (TDI), whichever is lower”, the TDI is converted to a percentage of the maximum daily dose and the lower value applies.
| Q3A(R2) drug substance | ≤ 2 g/day | > 2 g/day |
|---|---|---|
| Reporting | 0.05% | 0.03% |
| Identification | 0.10% or 1.0 mg TDI | 0.05% |
| Qualification | 0.15% or 1.0 mg TDI | 0.05% |
Q3B(R2) sets dose-banded thresholds for degradation products in the drug product, from 1.0% at low doses down to 0.10–0.15% above 2 g/day.
Rounding and comparison
Results below 1.0% are reported to two decimals and results from 1.0% to one decimal. Impurities at or above the reporting threshold are reported; identification and qualification apply when a result is above the threshold.
Q3A/Q3B do not cover biologics, peptides, oligonucleotides, radiopharmaceuticals, fermentation and herbal products, or clinical trial material. Assess mutagenic impurities under ICH M7, elemental impurities under ICH Q3D and residual solvents under ICH Q3C.
References
- ICH Q3A(R2) Impurities in new drug substances
- ICH Q3B(R2) Impurities in new drug products
- ICH Q6A Specifications
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.