Chromatography Forum

Column bleed it often indicated by a rising baseline and spectral characteristics of polysilanes being present.

In 2-D chromatography, the column bleed from the first dimension column forms a band across the chromatogram, eluting before other components in the second dimension. This band may include the tail of the injection solvent. Bleed from the second dimension column is difficult to observe as the second dimension column is short an narrow - thus has little stationary phase to bleed to start with - and what does bleed becomes a fairly constant signal in the background.

My guess on reasons for bleed is that both oxygen and heat damage every column to some degee. Other factors play a part as well, such as compunds that degrade the stationary phase and are introduced by injection in a sample.