PrÄchromatographische in situ-Derivatisierung von FettsÄuren im Picomol-Bereich

Pharmaceuticals and Drugs

“…It is generally used to introduce a chromophore, leading to the formation of strongly absorbing or fluorescent derivatives; to increase the selectivity of the separation; to enhance the sensitivity of detection; and to improve the linearity. It includes oxidation, reduction, hydrolysis, halogenation, nitration, diazotization, esterification, etherification, hydrazone formation, and dansylation (90). The primary aim of postchromatographic derivatization is the detection of the chromatographically separated compounds for better visual evaluation of the chromatogram.…”

“…In most instances, subsequent heating is necessary. Postchromatographic derivatizations have been extensively reviewed (90)(91)(92). In 1990, a new method, overpressured derivatization, was reported (93); this can be done by pressing an absorbent polymeric pad (prewetted with derivatization reagent) on the TLC plate.…”

“…The /3-radiation of radioactively labeled compounds can also be detected directly on the plate. These nondestructive detection methods allow subsequent isolation of compounds and can also be followed by microchemical and/or biological detection methods (90). Because physical detection methods are frequently not sufficient to establish the identity of compounds, they must be complemented by specific chemical reactions (derivatization).…”

Instrumental Thin-Layer Chromatography (Planar Chromatography)

“…An interesting example of prechromatographic derivatization directly on the TLC plate is the reaction of fatty acids in picomole amounts to fluorescing monodansylpiperazine and -cadaverine compounds (14). With a Linomat or an ATS 4, one reagent (monodansylpiperazine) is sprayed onto the starting zone and oversprayed with the analyte, followed by overspraying with the second reagent (dicyclohexylcarbodiimide).…”