Method
Troubleshooting
This
help file is designed to assist you in isolating the cause of changes
in performance of an HPLC separation. The initial assumption is that
you have either a validated method or a method which has worked in the
past, and that you have a specification for "system suitability" (i.e.,
you know how the method should behave).
To proceed, click on
the link below that best describes your problem.
1. Selectivity
and/or retention time changes
The retention time of one or more of your
peaks is out of specification.
2. Tailing
peaks
The retention times
of all your peaks are within specification, but the peak symmetry (asymmetry factor or tailing factor) of one or more of your
peaks is out of specification.
3. Abnormally
wide peaks (abnormally low plate count)
The retention times
and symmetries of all your peaks are within specification, but the width or plate count of one or more of your
peaks is out of specification.
4. Peaks
with shoulders
The retention times
of all your peaks are within specification, but one or more of your
peak shapes is abnormal in the form of a "shoulder."
5. Split
peaks
One or more of your
peaks is doubled or "split".
6. Flat-top
peaks
The retention times
of all your peaks are within specification, but one or more of your
peak shapes is abnormal in the form of a "mesa" or "flat-topped" peak.
7. Missing
peaks
One or more peaks
that should be in your chromatogram is missing.
8. Extra
peaks
Your chromatogram
contains one or more peaks that should not be present.
9. Excessive
pressure
Your operating
pressure exceeds specifications
10. Noisy
or drifting baseline
Your baseline drift and/or noise
exceed specifications, but your retention times and peak shapes are
within specification
11. Poor peak size repeatability
The repeatability (CV or %RSD) of peak areas for
replicate injections does not meet specifications.
12. Poor resolution.
The resolution between two critical
peaks does not meet specification.
Definitions of key terms.
Diagnostic
procedures.
References
and further reading.
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LC Resources, Inc. all rights reserved