Page 260 - Modern Derivatization Methods for Separation Sciences

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acids) play important physiological roles at extremely low concentrations in biological, food and
environmental samples. In general, the acids have no strong absorption and fluorescence, and show low
reactivity. Therefore, fluorescence pre-column derivatization is widely applied due to its sensitivity and
selectivity. A number of highly sensitive and selective derivatization reagents have been proposed for
quantification of the acids.

3.3.1—
Carboxylic Acids

Most of the derivatization reagents for carboxylic acids are of the fluorescence labeling type; the
reagents, generally, have a fluorophore (coumarin, phenanthrene, pyrene, quinoxaline, benzofurazan
and so on) and a reactive site (bromomethyl, diazomethyl, amine, hydrazine moieties etc.) for a
carboxylic group (Fig. 3.26). Therefore, these reagents are used for pre-column derivatization and the
derivatives are generally separated on an RP column.

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