How it works: Enter your column dimensions and particle size, then input the peak measurements from your HETP/qualification test (tracer injection). The calculator computes theoretical plate number N, HETP, reduced plate height h, and asymmetry factor As, then renders a PASS / MARGINAL / FAIL verdict against industry acceptance criteria. Uses the USP <621> half-height method. All values update live as you type.
Column and Process Parameters
µm
Peak Measurements
Asymmetry (at 10% peak height)
van Deemter Data
Enter HETP values measured at different linear velocities to fit the van Deemter equation and find the optimal flow rate for this resin/column combination.
| Velocity (cm/h) | HETP (cm) | |
|---|---|---|
Enter particle size and click Simulate data to generate 8 points, or type velocity/HETP pairs manually (3 minimum, 8 recommended).
Fitted Parameters
cm
cm²/h
h/cm
cm/h
cm
cm/h
HETP = A + B/u + C·u
Results
plates
N/m
Awaiting input
Enter column dimensions and peak measurements to qualify the column.
Enter retention volume and peak width to visualise the chromatogram.
Verdict
Reduced h
Asymmetry As
PASS
≤ 3.0
0.8 – 1.5
MARGINAL
3.0 – 5.0
0.7–0.8 or 1.5–1.8
FAIL
> 5.0
< 0.7 or > 1.8
Formulae (USP <621> half-height method)
N = 5.54 × (VR / Wh)2
HETP = L / N
h = HETP / dp
As = WR / WL (at 10% height)
Troubleshooting
General reference table
| Symptom | Likely cause | Action |
|---|---|---|
| Sudden HETP spike | Bed crack or wall separation | Repack immediately; inspect column hardware |
| HETP OK but pressure rising | Fouling or fines on frit | CIP with 0.5 M NaOH; repack if no recovery |
| Gradual asymmetry drift | Resin aging / ligand degradation | Run DBC test; replace resin if <80% initial |
| HETP varies with tracer type | Tracer–resin interaction | Use non-interacting tracer (NaCl for IEX, acetone for Protein A/HIC) |
| HETP high only at production flow | Mass-transfer limit (van Deemter C-term) | Reduce flow or use smaller particle size |
| HETP high at all flow rates | Packing irregularity (A-term) | Repack with controlled slurry density & pour speed |
| HETP inflated on small columns | Extra-column tubing dispersion | Shorten tubing; use narrower-bore (0.25–0.5 mm ID) |
| Double peak or shoulder | Bed heterogeneity or damaged distributor | Repack; check distributor/frit integrity |
van Deemter Curve
Fitted van Deemter curve will appear here.