fronting 

in chromatography
https://doi.org/10.1351/goldbook.F02534
Asymmetry of a peak such that, relative to the baseline, the front is less steep than the rear. In paper chromatography and thin-layer chromatography, 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] [Book]
PAC, 1993, 65, 819. (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 837 [Terms] [Paper]
Citation: 'fronting' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.F02534 RIS BibTex EndNote
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Last revised: February 24, 2014