D. Kratschmar et al., Analysis of oligosaccharides by MEKC with aminobenzoic alkyl esters as derivatization agents, CHROMATOGR, 50(9-10), 1999, pp. 596-600
Oligosaccharides derivatized with various aminobenzoic esters and aminobenz
onitrile were separated by micellar electrokinetic capillary chromatography
(MEKC) with sodium dodecyl sulfate (SDS). Methyl, ethyl and butyl aminoben
zoates as well as aminobenzonitrile were used as the derivatization agents
for homologous maltodextrins and the oligosaccharides from human milk. The
polarity of the label had a significant influence on the partition between
the aqueous and the micellar phases. Butyl aminobenzoate derivatives exhibi
ted the longest retention times and the best resolution of the sugars. In c
ontrast, derivatives of aminobenzonitrile gave the poorest separations owin
g to their relatively high polarity. The retention times of the oligosaccha
rides are inversely related to the degree of polymerization (DP) of the car
bohydrates. Malto-oligosaccharides up to a DP of 10 could be resolved. The
separation method was optimized with respect to the SDS concentration and t
he capillary temperature. Optimal resolution was found with a buffer consis
ting of 20 mM phosphate, pH 7.0, with 50 mM SDS at a temperature of 30 degr
ees C. Oligosaccharides from human milk could be separated by the optimized
method. The separation by MEKC showed a similar profile as that obtained b
y reversed-phase capillary HPLC, which demonstrates the analogy of the rete
ntion mechanism of both techniques.