The everyday bench and QC calculations — done right, free, and in your browser. USP <621> system suitability (with the USP tailing vs EP asymmetry distinction spelled out), Henderson-Hasselbalch buffer recipes, ICH Q2 LOD/LOQ, USP <905> content-uniformity acceptance value, and Grubbs/Dixon outlier tests. Nothing is uploaded — every number is computed locally.
System suitability — USP <621> / EP
Retention
Efficiency
USP tailing factor — measured at 5% peak height
EP symmetry (asymmetry) factor — measured at 10% peak height
USP Tailing (T) is measured at 5% peak height; the EP/Ph.Eur Symmetry factor (As) is measured at 10%. They use the same formula at different heights and are not interchangeable — reporting the wrong one is a classic finding. Both are shown below.
Mix the salts directly — never titrate a mobile phase to pH by eye. Titrating changes the ionic strength run-to-run and drifts retention times. This gives you the exact weight/volume of each component so the buffer is reproducible.
LOD / LOQ — ICH Q2(R2)
Method A — standard deviation of the response & slope of the calibration curve
LOD = 3.3σ/S · LOQ = 10σ/S
Paste values (one per line, or comma/space separated). Their sample standard deviation fills σ automatically.
Method B — signal-to-noise
S/N = H/N. A signal-to-noise of 3:1 is the usual LOD and 10:1 the LOQ. If you give the injected concentration, the LOD/LOQ concentrations are back-calculated.
Content / dosage-unit uniformity — USP <905> acceptance value
The Acceptance Value AV = |M − X̄| + k·s, with k = 2.4 for 10 units and k = 2.0 for 30. The reference value M locks to 98.5 or 101.5 (or T) when the mean drifts. The Stage-1 / Stage-2 logic is applied automatically.
OOS outlier tests — Grubbs & Dixon's Q
Grubbs' test screens the single most extreme value: G = |xsuspect − X̄| / s. Dixon's Q (for n = 3–10) uses the gap-to-range ratio.
Warning: a statistical outlier test alone cannot invalidate a chemical result. An out-of-specification result may only be discarded after a documented laboratory investigation identifies an assignable root cause (FDA OOS guidance).
These calculators apply published compendial and ICH formulae (USP <621>, USP <905>, ICH Q2(R2), Henderson-Hasselbalch, Grubbs/Dixon) to values you enter, entirely in your browser. Acceptance thresholds shown are common defaults — always apply the criteria registered in your own validated method. Results support, but do not replace, your laboratory's data review and QA oversight. Generated via the MolWard Platform.
