Preparative Layer Chromatography in Food Analysis
Preparative layer chromatography (PLC) is a method used to separate and isolate larger amounts of material (e.g., 1-1000 mg) than are applied in analytical thin layer chromatography (TLC) or high performance TLC (HPTLC). Micropreparative TLC is the term used when lower amounts in the preparative range are chromatographed on thinner preparative layers, most often 0.5 , or 0.25 mm analytical layers. The purpose of PLC is to obtain pure compounds for such tasks as further chromatographic (e.g., gas chromatography  and column high performance liquid chromatography [HPLC] ) or spectrometric (e.g., infrared, ultraviolet [UV], nuclear magnetic resonance [NMR], and mass spectrometry [MS] [4,5]) analysis; investigations of physical, chemical, pharmacological, or biological properties; obtaining analytical standards; or additional reactions in a synthetic sequence. Simple and inexpensive ascending capillary ﬂow development in a closed chamber is most widely used (classical PLC, CPLC), but ﬂow achieved by application of pressure or centrifugal force can also be used (forced ﬂow PLC, FFPLC). This chapter brieﬂy
reviews the procedural steps and instrumentation of modern PLC and gives selected applications to food analysis. For more details on techniques and applications of CPLC, readers should consult a recent comprehensive book .