Choice of thin-layer chromatographic systems for the routine screening for acidic drugs during toxicological analyses

The efficiencies of fifteen thin-layer silica gel chromatographic systems in separating commonly encountered acidic drugs are compared. The discriminating powers of the systems are measured both individually and in combination. Ethyl acetate and chloroform-methanol (9:1) are found to be the two best systems. The combination of the ethyl acetate-methanol-ammonia (85:10:5) system with either of these gives the best pair of systems. Various sequences of spray reagents are also examined.