Derivatization reactions in capillary electrophoresis of amino acids

The article deals with derivatization reactions employed in capillary elect rophoresis (CE) of amino acids (AA). Currently preferred reactions are clas sified into seven groups according to their reaction mechanisms and schemes . Many of them were originally developed for liquid chromatography of AA an d their implementation in CE usually requirer minor modifications of the wo rking conditions depending on specificities of the process. So far, more th an fifty derivatization reactions of AA have been reported in the literatur e in the context of CE. This apparently reflects not only different reactiv ities of AA with different derivatization agents but also different envisag ed applications of CE. Therefore, in some instances, requirements for high reaction rates determine the choice (e.g., post-column derivatizations of A A, iri vivo monitoring of AA in microdialysates from biological processes). On the other hand, a need for the detection of amol-zmol amounts of AA may be often better met by the reactions characterized by lower reaction rates . Some of the derivatization agents provide very selective detections of a specific class of AA, e.g., detection of sulfanyl amino acids based on thei r reactions with 2,2'-dinitro-5,5'-disulfonyl-dibenzoic acid. So far, only a limited number of the derivatization reactions is applicable in the AA se quenations of peptides and proteins by CE. Here, phenyl isothiocyanate, 7-( N,N-dimethylsulfamoyl)-2, 1,3-benzoxadiazol-4-yl isothiocyanate and 1-fluor o-2, 4-dinitrobenzene appear to have a prominent position.