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Toxicological screening ,Toxicological screening by chromatography

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  229

2026-10-15

491

Toxicological screening

Toxicological screening by chromatography

Thin-layer chromatography Thin-layer chromatography (TLC) is usually applied to urine samples or, if these are not avail able, to stomach contents that have been purified prior to extraction. Any particulate material in the stomach contents should be removed by filtration or centrifugation prior to solvent extraction. Further purification by removal of fats and other dietary material can be carried out using a back-extraction step, as described below. Many TLC systems have been developed for use in hospital toxicology. These include the commercial Toxilab system, which provides standards for the substances and metabolites most commonly encountered in intoxicated patients. The most generally used mobile phase is chloroform–methanol (9:1 v/v), although some countries now prefer the less toxic dichloromethane to chloroform. In hospital toxicology it is advisable to use at least two separate mobile-phase systems to obtain a more definitive result. Silica-gel plates of 20 cm x 20 cm with or without fluorescent indicator are the most popular, although smaller sizes can also be used.