V.A. Kormishin, A.V. Voronin, I.F. Shatalaev

Broad application of a thin layer chromatography (TLC) is connected with high efficiency, simplicity, sufficient specificity of a method. Densitometry, in turn, provides TLC possibility of semi-quantitative definition of analyzed substances and documenting of results. However the high cost of the specialized analytical equipment, in particular scanning densitometers and the software, to the majority of laboratories of expert establishments doesn't allow to use in full possibility of TLC. The purpose of the real work - definition of some analytical characteristics and opportunities of quantitative definition of a technique of judicial and chemical research of biological liquids on opiates, barbiturates, phenylalkilamins and some other substances the TLC method with application of computer densitometry. For research used: plates for TLC «Sorbfil PTSH-PA-UF» of 10х10 cm; standard metanolny solutions of morphine, codeine, barbital, phenobarbital, barbamyl, ephedrine, doxylamine, amitriptyllin, baclofen, dimedrol, verapamil of concentration of 1,0 mg/ml (producer ABBOT firm); the model samples of urine which aren't containing drugs, psychotropic substances; digital camera, tablet scanner; computer program for densitometry «TLC-manager» (version 3.12, developer Plakhotny I.N. Dnepropetrovsk). Plates after a chromatography, manifestation and drying scanned on the tablet scanner and photographed by means of the digital camera, the received files of the jpeg format processed by means of the TLC-manager program. The limit of detection made: for ephedrine, doxylamine, amitriptyllin, verapamil of 1,0 µg in test; for morphine, codeine, barbital, phenobarbital, barbamyl, dimedrol of 5,0 µg in test; for baclofen 0,5 µg in test. Reduction of size of a limit of detection is brought by raster manipulations with electronic image chromatography - changes of sharpness, intensity of the image, change of parameters of brightness and contrast, possibility of viewing chromatography in a negative. Calibration dependence «the area of a spot (Y) ? amount of substance, µg (X)», constructed in the range of concentration of 5,0-250,0 µg/ml, is described by the equation of polynomial (square) regression that demands use more than three calibration samples. For simplification of an analytical task us application of linear regression, thus quantity of calibration samples was offered was reduced to two, thus the relative error of definition didn't exceed 28 % that is acceptable for a preliminary analysis stage. The smallest size of a mistake is reached at concentration of substances in test of 100,0 µg/ml.