Thin-layer and gas chromatographic separation of the stereoisomers of some synthetic pyrethroids

Summary Analytical conditions were established permitting the enabling separation of the cis-trans stereoisomers of selected synthetic pyrethroids with help of thin-layer and gas chromatography. Using the example of permethrin the possibility of isomeric separation in an oilbased commercial formulationis also illustrated.     

Thin-layer chromatography of some organic selenium compounds

The thin-layer chromatographic behavior on silica gel and consequent rapid separation of some selenopyran derivatives together with some intermediates of their synthesis are described. The compounds examined were selenochrom-4-one, selenochroman-4-ol, 2-nitrobenzyl phenyl selenide, 2-aminobenzyl phenyl selenide, and 6H-dibenzo[b,d]selenopyran. The chromatographic results show that it is possible to obtain rapid separations with small amounts (μg) of substance by a simple monodimensional technique using a two-component eluting solvent.     

Thin-layer chromatographic analysis of some new 1,8-disubstituted triphenodioxazines

Summary A thin-layer chromatographic method for the separation and identification of hitherto unknown disubstituted triphenodioxazines in submicrogram amounts has been developed using silica gel plates. The solvent systems used are acetone-petroleum ether (6040), benzene-petroleum ether (8020) and acetone-petroleum ether (5050). The compounds are detected by spraying the plates with 0.05 mol dm^–3 sulphuric acid.     

Thin-layer chromatographic separation and analysis of polynuclear aza heterocyclic compounds

Many thin-layer Chromatographic systems can be used for the general separation of aza heterocyclic compounds from polynuclear aromatic hydrocarbons. Several can be used for the separation of the aza compounds from each other. With alumina as the adsorbent the sterically hindered aza heterocyclic compounds can be readily separated from the non-hindered aza compounds.The use of the trifluoroacetic acid spot test on the thin-layer plate is discussed. Spectral data for the aza compounds are presented and discussed.     

Thin-layer chromatographic screening procedure for some drugs in horse plasma

A thin-layer chromatographic screening procedure for some basic, neutral and acidic drugs was developed using 3 ml of horse plasma. Chloroform-2-propanol (95:5, v/v) was used as the extraction solvent. The drugs were identified by a high-performance thin-layer chromatographic plate and spraying successively with some detection reagents. In this study, the extraction recovery rates and the detection limits were determined at the same time.     

Thin-layer chromatographic separation of some closely related olefinic benzo- and naphtofurans

Summary A method is reported for the separation of 16 closely related 2-(1, 2-diphenylvinyl)-3-phenylbenzofuran and 2-(1, 2-diphenylvinyl)-1-phenylnaphtho[2,1-b] furan derivatives on thin-layers of silica gel-G.     

Thin-layer chromatographic analysis of some substituted dianilino-3,6-dihalo-1,4-benzoquinones

Summary The seoaration and identification of some substituted dianilino-3,6-dihalo-1,4-benzoquinones in submicrogram quantities on thin-layer of silica gel G using various nonaqueous developing solvent systems is reported. R _F values are obtained with a reproducibility of ±0.02 units.     

Thin-layer chromatographic screening procedure for undeclared synthetic drugs in Chinese herbal preparations

A simple and rapid thin-layer chromatographic procedure was developed for the detection and presumptive identification of seventeen synthetic drugs previously reported as adulterants of Chinese herbal preparations. Depending on its complexity, the sample may be directly extracted into aqueous ethanol, or stepwise fractionated into acidic, basic, and neutral components. Extracts are analyzed on silica gel layers containing a fluorescent indicator with the aid of two solvent systems. Spots are visualized under short and long wavelength ultraviolet lights. The procedure was successfully tested on synthetic and commercial samples.