Fronting Peaks

Fronting Peaks

Getting peaks that are ‘fronting’ is not something that arises very often, but fortunately the causes are simple, and the fixes straightforward.

The most common cause of fronting is column overload – essentially putting too much sample onto your column. This causes the analytes to have insufficient interaction with the phase of the column, resulting in a sort of ‘tidal wave’ of material that elutes with an initial front-loaded peak followed by a long tail.

This is more likely to be the case if you’re seeing fronting on the majority of your larger peaks, and can be resolved in two ways:

- Reduce the amount injected by diluting the sample or increasing the split ratio. 

- Increase the inner diameter of the column and/or the film thickness.

The other cause of fronting peaks – an incompatible stationary phase – is more of a method-development issue and is more likely if you’re seeing fronting on just one or two peaks. A typical case would be non-polar analytes on a polar column (or vice versa), which causes the peak to be poorly retained. Molecular sieve phases are particularly prone to this. We’d always recommend checking the literature to find a suitable column phase for your analyte.

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