Page 239 - Modern Derivatization Methods for Separation Sciences

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mm I.D.). Mobile phase: gradient elution. Flow-
rate: 1 ml/min. [Reproduced from ref. 35, p. 21, Fig. 1.].

(2) Carbonyl Chlorides and Fluorides

The derivatization of these type reagents are based on the amidation of amines with carbonyl chloride
and fluoride groups (Fig. 3.5B). 9-Fluorenylmethyl chloroformate (Fmoc-Cl) is used as a pre-column
derivatization reagent for primary and secondary amino compounds (Fig. 3.9) [36]. The reaction
proceeds in borate buffer (pH 8) within 2 min, and the derivatives are stable. However, Fmoc-Cl and its
hydrolyzed product are highly fluorescent, hence they have to be removed by extraction with an organic
solvent, pentane. As with DNS-Cl, Fmoc-Cl is also reactive towards a phenolic hydroxyl moiety.
Further, the reagent combines with the imidazole ring of amino compounds. In this reaction, tyrosine
and histidine give the corresponding mono and disubstituted derivatives.

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