TLC separation and derivative spectrophotometry of some amino acids

Chromatographic systems for the separation of amino acid mixtures on RP-18 as a stationary phase have been elaborated. The best results were obtained using methanol-water (1:1, v/v; 1:3, v/v; 1:5, v/v) as a mobile phase. The following amino acids have been examined: asparagine, arginine monohydrochloride, cystine, cysteine chloride, glycine, histidine monohydrochloride, hydroxyproline, isoleucine, leucine, lysine monochloride, methionine, ornithine monohydrochloride, phenylalanine, proline, threonine, tryptophan, tyrosine, serine, valine. Histidine (as monohydrochloride) and methionine were determined by first-, second- and third-derivative spectrophotometry in a mixture of several amino acids.