POTENTIAL AND PITFALLS OF CHROMATOGRAPHIC TECHNIQUES AND DETECTION MODES IN SUBSTANCE IDENTIFICATION FOR SYSTEMATIC TOXICOLOGICAL ANALYSIS

The potential and the constraints of thin-layer chromatography (TLC), gas chromatography (GC) and high-performance liquid chromatography (HP LC) towards substance identification, together with their detection mo des, are considered. The latter include colour reactions on the plate, molecular masses through chemical ionization mass spectrometry (MS) a nd diode-array UV spectrophotometry. Evaluations are carried out by th e mean list length approach. Not surprisingly, GC-MS and HPLC-diode ar ray detection qualify as the two most powerful combinations. However, one does not necessarily need to have access to these sophisticated de tection modes: the identification power of TLC and colour reactions pl us GC or HPLC retention indices is high and even a suitable combinatio n of TLC and colour reactions remains a valuable tool. After analysis, the findings for the unknown substance(s) must be matched against dat abases containing the behaviour of reference substances. The search pr ocess for the computerized retrieval of potential candidates must allo w the handling of all possible combinations of identification techniqu es applied.