Download Troubleshooting Common HPLC Problems

Performance Monitoring
Use Your Test Method
(Known Performance)
Plate Count - Efficiency of the
Separation
* Monitor at least One Peak in one injection
- Plate Count (Peak width relative to RT),
- Peak Asymmetry,
- Retention Time and/or Retention parameter
- Relative Retention Time for Critical Pair of Analytes.
- Peak Response
* A "Plate Count" Actually Is a
Determination Of Both
The Column AND Instruments'
Performance
* Inject Multiple Runs
- Precision (at least 5 injections)
- Accuracy (Use Control Samples)
Performance Monitoring
Column Efficiency:
N = the number of Theoretical Plates
a = is a constant depending on the Method used
tr = retention time of peak
W = the peak width (time units) at a given peak height
Performance Monitoring
Band Spreading
tR
N=a
(
tr
W
2
)
h
t0
w
METHOD
Peak Width at Half Height
Peak Width at 4.4% Peak Height (5 Sigma)
Tangent
a
5.54
25.0
16.0
Dr. Shulamit Levin, Medtechnica
* Band Spreading Impacts Chromatographic
Performance -- The Greater The Band Spreading,
The Poorer The Performance (ie; Resolution)
* Band Spreading Contains Both An Instrument
AND A Column Contribution
2