Peak Fronting in GC

Created by Agilent Knowledge Portal 8 months ago | Last modified by Carlos Vargas 7 months ago

This Information Applies To: Agilent GC Systems

Issue

Peak fronting is present in a chromatography peak when it has an excessive asymmetry with a leading edge. A normal peak is almost symmetrical.

Other chromatographic problems are identified in Basic Troubleshooting for GC Systems . Regular maintenance of your instrument in accordance with the recommended maintenance schedule will reduce the incidence of chromatography problems.

Background

Fronting can be caused by sample solvent, component concentration, injection conditions, column selection, and other reasons. Figure 1 shows no fronting, minimal fronting and excessive fronting.

Figure 1. Peak fronting
1. Symmetrical peak with no fronting, 2. Nonsymmetrical with minor fronting, 3. Nonsymmetrical with major fronting

Resolution

Possible causes of peak fronting include:

Possible cause of fronting

Solution

Column overload (component concentration too high)

Dilute the sample, check that the correct volume has been injected, check the syringe size, decrease the injection volume, or increase the split ratio

Improper injection technique (slow/erratic plunger depression)

Check that the syringe plunger is moving freely. The solution should be pulled into the syringe body (no solution left in the needle), and moving freely and fast when plunger is depressed. Use an autosampler

Component highly soluble in the injection solvent (Reverse Solvent Effect)

Change the injection solvent or use a retention gap

Mixed sample solvent with large differences in polarity or boiling points

Change the sample solvent

Improper column installation

Remove and reinstall the column. See Capillary Column Installation Quick Reference Guide

Column contamination

Bake out the column. Limit the bake-out for 1 to 2 hours