A new spray reagent for the detection of synthetic pyrethroids containing a nitrile group on thin-layer plates

This paper describes a new spray reagent for selective detection of synthetic pyrethroids containing -cyano group i.e. lambda-cyhalothrin, deltamethrin, cyfluthrin and fluvalinate by thin layer chromatography. These synthetic pyrethroids on alkaline hydrolysis, yield a cynohydrin derivative which degrades to give HCN and a corresponding aldehyde. This liberated HCN reduces 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to formazan, a pink product in the presence of phenazonium methosulfate (PMS). The pink colour formed remain stable for more than 24 h. Other group of insecticides like organophosphorus, organochlorine and carbamate do not interfere in the determination. Pyrethroid insecticides not containing hydrolysable nitrile group also do not interfere. The limit of detection is from 0.5 to 1 μg.     

Sensitive derivatization reagents for hydroxyl and amino compounds for thin-layer or high-performance liquid chromatography with fluorescence detection

Three fluorescent derivatization reagents for compounds having hydroxyl and/or amino groups are described. 4-(2-Phthalimidyl)benzoyl chloride, 3-(2-phthalimidyl)benzoyl chloride and 3-(2-phthalimidyl)-4-methoxybenzoyl chloride, prepared from the corresponding phthalimidylbenzoic acid, were stable at room temperature and condensed quantitatively with alcohols, amines and amino acids in the presence of alkali under mild conditions to give strongly fluorescent derivatives. The derivatives were separated by thin-layer and high-performance liquid chromatography.     

Surface derivatization of ketones and primary amines on thin-layer chromatographic plates for detection by secondary ion mass spectrometry

Exposure of the surface of a thin-layer chromatogram to vapors emitted from a solution containing a derivatization reagent results in the conversion of carbonyl-containing (e.g., steroids) or primary amine-containing molecules (e.g., small peptides) on the chromatogram into ionic derivatives suitable for sputtering in secondary ion mass spectrometry. No reduction in the chromatographic resolution is observed because liquid matrices or reagents are never applied directly to the surface.