This website, part of the Chemguide Understanding of Chemistry site by Jim Clark, aimed at A-level or similar advanced chemistry courses, provides a background to chromatography.
Topics covered include thin layer chromatography, column chromatography, high performance liquid chromatography (HPLC), gas-liquid chromatography, and paper chromatography.
http://www.chemguide.co.uk/analysis/chromatogrmenu.html
