Base line drift, Base line noise, Broad peaks, Change in height, Negative peaks, Ghost peaks in HPLC
Sunday, July 15, 2012
Base line drift
What You Expect What You Got
Base line noise
What You Expect What You Got
Broad peaks
What You Expect What You Got
Change in height
Disease
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Medicine
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Fluctuation of column temperature
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Stabilize. Use column oven
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Contamination of mobile phase/
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Use HPLC grade solvent. Degas
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Air in the detector cell
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Clean cell. If necessary use a pressure restrictor at outlet
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Plugged detector outlet line
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Replace
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Default mixing
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Check mixer unit. Check flow rate and composition
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Plugged detector outlet line
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Replace
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Strongly retained materials
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Flush column with strong solvent
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Unoptimized detection
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Optimize detector
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Base line noise
What You Expect What You Got
Disease
|
Medicine
|
Air (mobile phase, detector cell, pump)
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Flush system, prime pumps, degas mobile phase
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Pump pulse
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Use a pulse damper
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Incomplete mixing
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Promote complete mixing
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Electronic
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Check electronic equipment in the same line
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Leak
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Please See No Peaks Or Very Small Peaks
|
Disease
|
Medicine
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Leak
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Please See No Peaks Or Very Small Peaks
|
Bad quality mobile phase
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Use HPLC grade solvents
|
Electronics
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Locate problem.Get servicing
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Cell contaminant
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Clean detector cell
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Weak lamp
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Replace detector lamp
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Broad peaks
Disease
|
Medicine
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Altered mobile phase
|
Make new
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Low flow rate
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Increase
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Leak
|
Please See No Peaks Or Very Small Peaks
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Incorrect detector settings
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Check and correct
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Column overload
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Please see Retention times are not constant
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Void volume. Tubing too long or to wide
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Use 0.010" tubing. Shorten path
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Low buffer concentration
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Increase
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Column or guard column contamination
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Replace
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Void volume at inlet
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Repack
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Change in height
Disease
|
Medicine
|
Sample deterioration
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Use fresh sample
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Leak
|
Please See No Peaks Or Very Small Peaks
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Non-reproducible sample volume
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Ensure loop is completely filled
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Low detector response
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Check detector settings and operating conditions
|
Negative peaks
What You Expect What You Got
Disease
|
Medicine
|
Recorder connections
|
Check polarity
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Refractive index of mobile phase higher than that of solute
|
Change mobile phase
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Vacancy peaks
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Originate from great difference in composition between sample solvent and mobile phase. Dissolve sample im mobile phase
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Mobile phase more absortive than sample components
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Use mobile phase that is transparent at the wavelength used
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Ghost peaks
What You Expect What You Got
Disease
|
Medicine
|
Contamination of injector or column
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Always flush injector after each injection.
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Retained compound from previous injection
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Flush colunm with strong solvent after operation to remove late eluting compounds
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A good instrument for removing ghost peaks in gradient HPLC is the use of a trap column like the Ghost-Guard-LC:
ReplyDeleteThe Ghost-Guard-LC increases reliability of gradient trace impurity analysis by eliminating Ghost Peaks caused by mobile Phase or hardware components.
In gradient elution analysis using a HPLC system, impurities from the mobile phase solvents, mobile phase containers, flow lines, pump, gradient mixer etc., can cause peaks to appear in chromatograms. If such ghost peaks appear, it can be difficult to distinguish them from peaks corresponding to trace sample components, reducing analysis reliability.
Furthermore, identifying the source of ghost peaks can be extremely time-consuming, and has been a source of frustration for chromatographers, particularly in trace analysis work. The Ghost-Guard-LC column enabled efficient removal of impurities from mobile phase solvents and other sources by adsorption to easily avoid the effects of ghost peaks in analysis.
Ghost-Guard-LC columns can be used to efficiently adsorb impurities in both aqueous and organic solvents. Using the Ghost-Guard-LC in reverse-phase gradient elution, which is widely used in liquid chromatography, allows adsorbing and removing all components that cause ghost peaks from mobile phases and their flow lines. This can significantly increase the analytical accuracy of trace analysis. Previously, if ghost peaking interfered with analysis, it was necessary to identify the causes and implement countermeasures, which was extremely time-consuming. In contrast, using the Ghost-Guard-LC easily removes the causes without any need to investigate their source.
http://ghost-guard.iip.de/?page_id=40