Separation of glucooligosaccharides and polysaccharide hydrolysates by gradient elution hydrophilic interaction chromatography with pulsed amperometric detection

Commercial glucooligosaccharide mixtures (Polycose) and polysaccharide hydrolysates (acid and enzymatic) were fractionated by hydrophilic interaction chromatography and observed by pulsed amperometric detection. Seven peaks were observed when 625 ng of glucose oligomers in Polycose were fractionated. The between-run precision of retention times (n = 10, 100 μg, 15 peaks) ranged from a relative standard deviation (R.S.D.) of 0.09 to 0.40%; between-run precision of peak areas (n = 10) for the same separations had values that ranged from 2.66 to 14.4%. Injection-to-injection time was 48 min. When polysaccharide hydrolysates were fractionated using a gradient program capable of resolving all of the oligosaccharide species, dextran-derived -(1→6)- glucooligosaccharides were retained to a greater degree than amylose-derived -(1→4)-glucooligosaccharides, which were retained to a greater degree than β-(2→1)-fructooligosaccharides derived from inulin. Excluding the peaks that eluted before glucose or fructose, 25 to 35 peaks were observed after fractionation of the hydrolysates. Differences in elution profiles were observed between acid and enzymatic hydrolysis products of the same polysaccharide as well as between hydrolysis products of different polysaccharides. In conjunction with high-performance size-exclusion chromatography, the method demonstrated the effect of preheating starch before hydrolysis with isoamylase.