fronting

in chromatography
https://doi.org/10.1351/goldbook.F02534
@A00486@ of a peak such that, relative to the baseline, the front is less steep than the rear. In paper @C01075@ and @T06346@, it refers to the distortion of a spot showing a diffuse region in front of the spot in the direction of flow.
Sources:
Orange Book, 2nd ed., p. 96 [Terms]
PAC, 1993, 65, 819. (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 837 [Terms] [Paper]