ABSTRACT

Analysis o f starch and amylodextrin, which are homopolymers o f glucose with no unique chromophore or fluorophore for direct detection, has al­ ways been a challenge. Many analytical techniques have been applied to starch analysis. High performance size exclusion chromatography (HPSEC) with laser light scattering (LLS) detection and refractive index (RI) detection [1-5] allows direct detection o f carbohydrates and provides molecular weight distribution information. However, the nonspecific re­ sponse o f the RI detector prohibits the use o f gradient eluents and hampers the separation resolution o f amylodextrins. High performance capillary electrophoresis (HPCE) with laser-induced fluorescence (LIF) detection provides attractive separation resolution o f amylodextrins [6,7], but a pre­ column derivatization o f amylodextrins is required to produce spectroscopi­ cally active compounds. The invention o f the pulsed amperometric detector (PAD) [8] has allowed direct detection o f carbohydrate at alkaline pH and the use o f gradient eluents for chromatographic separation. HPCE and high performance anion-exchange chromatography (HPAEC) have been coupled with PAD for carbohydrate analysis [9-16]. The H PCE-PAD sys­ tem has been applied to separate sugar alcohol and oligosaccharide mix­ tures [9,10], and its application to separation o f polysaccharide mixtures remains to be studied. The HPAEC-PAD system, however, has already proven to be a powerful analytical technique for amylodextrins. Separation

and detection o f amylodextrins with degree o f polymerization (dp) > 50 can be easily obtained [11,13,15,16].