How much sample can I inject on my LC column?
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Two different types are possible:
- Mass overload (too much analyte injected on the column)
- Volume overload (too much liquid injected on the column)
The chromatograms are somewhat different in these 2 situations.
In mass overload, the analyte molecules saturate the silica at the inlet end of the column which causes the excess molecules to move forward down the column without much interaction, reducing in turn the analyte retention time and showing a "shark fin" peak shape (fronting).
Volume overload occurs when the injected sample volume is large enough to carry analyte molecules through a significant proportion of the interstitial volume within the column and leads to shark fin type peaks as well and later elution times.