Thin-layer chromatography

Thin-layer chromatography for pesticide residue analysis is a valuable technique which finds favour with many laboratories. It can be made as sophisticated or as simple as the operator wishes and in its basic form is more than adequate as a screening technique. Thin-layer plates of high quality can be purchased ready made and are available with a wide range of adsorbents and surface treatments. They can be expensive however and may be a budgetary constraint for developing countries. Plates can also, with practice, be prepared in the laboratory. This latter option is cheaper once the materials and spreading equipment have been purchased although the prepared plates will be found to vary in quality until suitable experience has been gained by the staff. This latter option is nonetheless recommended for laboratories in developing countries. Used as a screening procedure on partly cleaned-up extracts, TLC can save time, and more importantly, reagents, in certain circumstances.