Kostenloser Plate Number Rechner
Berechnen Sie theoretical plate number N und plate Größe HETP for HPLC und GC column efficiency assessment.
Theoretical Plates (N)
25,600
Theoretical Plates (N) vs Retention Time (tR)
Formel
## Theoretical Plate Number The plate count N measures column efficiency. Higher N means sharper peaks and better separation potential. ### Formula **N = 16 × (tR / w)²** **HETP = L / N** where w is the peak width at the base (4-sigma). Modern HPLC columns typically give N = 10,000-20,000 per 25 cm column. UHPLC with sub-2-um particles can achieve 30,000+ plates.
Lösungsbeispiel
A peak at 10 min with 0.25 min base width on a 25 cm column.
- 01N = 16 × (10 / 0.25)² = 16 × 40² = 16 × 1600 = 25,600 plates
- 02HETP = 25 / 25600 = 0.000977 cm = 9.8 um
Häufig Gestellte Fragen
What is a good plate count?
For a 25 cm HPLC column: N > 10,000 is acceptable, > 15,000 is good, > 20,000 is excellent. For GC capillary columns: N can exceed 100,000 due to much longer columns.
Why does plate height matter?
HETP measures efficiency per unit length. Smaller particles give lower HETP (higher efficiency). A 5 um particle column has HETP ~10 um at optimum flow, while a 1.7 um column achieves ~3.5 um.
What causes low plate count?
Extra-column band broadening (dead volume in tubing and fittings), column deterioration, voids at column head, temperature gradients, and operating far from the optimum flow rate.
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