Moreover, the analysis of these compounds
as well as its sequencing plays an important role in protein and
metalloprotein determination; thus, a considerable amount of research
in developing analytical protocols for amino acids determination
has been reported. Several liquid chromatographic methods
are described to this end [3,4]. The absence of a strong fluorescence
or UV-vis-active group leads to the use of different derivative
agents to obtain a chromophore-containing derivative
product in order to increase the sensitivity [5]. Among the most
commonly employed, o-phthalaldehyde [6], dansyl chloride
(Dns-Cl)1 [7], phenylisothiocyanate [8–10], and phanquinone [11]
have been reported as derivative reactives for different detection
techniques. The use of capillar electrophoresis provides speed of
analysis over HPLC without the use of gradient in addition to the
lower solvent waste production. Therefore, many publications have
dealt with the separation of amino acids by CE without [12–14] or
with derivatization [15–18]. In most of them, the use of naphthalene-2,3-dicarboxaldehyde
(NDA) as derivative agent is preferred
in order to solve the problems associated with the rapid degradation
of o-phthalaldehyde derivatives. Different detection techniques are
employed