Application of Two-Dimensional High-Performance Thin-Layer Chromatography to Qualitative and Quantitative Toxicological-Chemical Analysis

The present paper describes various application possibilities of high-performance thin-layer chromatography (HPTLC) for qualitative and quantitative toxicological-chemical analysis. Exemplified by 115 toxicological relevant drugs, a simple and fast two-dimensional HPTLC procedure is presented, suited for the undirected qualitative toxicological-chemical analysis. Here, we demonstrate that the separation performance can be increased significantly by identifying substances on the basis of the two migration distances together with the remission spectra maxima, measured with a HPTLC scanner (densitometer). The values calculated for the discrimination power and the identification power were found to be comparable with those of other chromatographic procedures, commonly used for toxicological-chemical analysis (high-performance liquid chromatography [HPLC], gas chromatography-mass spectrometry [GC-MS], and liquid chromatography-mass spectrometry [LC-MS]). While a scanner increases clearly the efficiency of qualitative analysis, it is indispensable for quantitative analysis. The broad applicability of the HPTLC-densitometry for the directed quantitative toxicological-chemical analysis has been shown by the description of methods for 144 drugs. Particularly, it has to be emphasized that the suitability of the two-dimensional HPTLC has been demonstrated also for quantifications with internal standard for a large number of determinations of relevant drugs, leading to a significant increase in efficiency. For sample preparation of biological material, seven methods have been used for the tested drugs. With a total of ten mobile phases (solvent mixtures), it has become possible to determine all 144 substances by HPTLC. The advantages of HPTLC (low price, high variability), but also its indisputable disadvantages in its application in the toxicological-chemical analysis are discussed. HPTLC in the presented form is suitable for both qualitative and quantitative analysis and may well be of benefit to resolve specific problems, even in the presence of more sophisticated analytical methods in a toxicological laboratory.