System Suitability Calculator
Paste your replicate injections and get %RSD, retention time precision, tailing, plate count, resolution and signal-to-noise checked against your limits in one go.
- USP <621> and Ph. Eur. 2.2.46
- HPLC and UV-Vis
- Every calculation step shown
- No sign-up
Four steps, or fewer
- Check the acceptance criteria. The defaults are common USP values; change them to match your method or monograph.
- Enter or paste the replicate injections. Only the response is required; add retention time, tailing and plates if your method requires them.
- Add resolution and signal-to-noise if your method has those criteria.
- Read the verdict, check the calculation steps and print the report for your raw data file.
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 system suitability is calculated
System suitability shows that the chromatographic or spectrophotometric system works as intended before samples are analysed. Injection precision is expressed as the relative standard deviation of replicate responses.
%RSD = s / x̄ × 100 (%RSD and %CV are the same quantity)
Typical criteria
| Parameter | Typical requirement |
|---|---|
| Response %RSD (assay, 5–6 injections) | ≤ 2.0%, or the limit in the monograph |
| Retention time %RSD | ≤ 1.0% (method-specific) |
| Tailing (symmetry) factor | ≤ 2.0 unless otherwise specified |
| Theoretical plates | Method-specific, often ≥ 2000 |
| Resolution of the critical pair | Method-specific, often ≥ 2.0 (≥ 1.5 is baseline separation) |
| Signal-to-noise | ≥ 10 at the reporting level for impurity methods |
Since the harmonised USP <621> and Ph. Eur. 2.2.46, the maximum permitted %RSD for an assay can depend on the number of injections and the upper specification limit. Where your monograph gives a limit, use it.
References
- USP General Chapter <621> Chromatography
- Ph. Eur. 2.2.46 Chromatographic separation techniques
- ICH Q2(R2) Validation of analytical procedures
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.