Chromatography Forum

The GC I have been using is not presenting good peak formats anymore, in methods that had already been used in the routine for years. The initial solvent peaks of the chromatogram are the most affected and show breaks and are splited.
Is there any explanation for this or anything I can do to solve the problem?

Yes there is an explanation and yes it can be fixed, but not unless you give us some details of set up and methods to work with. The more you don't tell us the more we can't help you.