For the analysis of polysaccharides such as starch, which does not dissolve easily in water, samples used to be dissolved in DMSO before doing the analysis by SEC mode with an aqueous an eluent. However, this method was unsatisfactory as undissolved components were left undetected. In contrast with the above, if a mixed eluent of DMSO/DMF containing LiBr is used as an eluent, the solubility of starch in the eluent is increased allowing a more accurate SEC analysis. There are some cases in which starch has ionic functional groups such as carboxyl groups. An addition of LiBr to the eluent allows SEC analysis without interference from the ionic groups. The sample used in this analysis example was prepared by adding DMSO to starch and then heating the mixture to 120 °C to dissolve the starch using OHpak SB-806 HQ, a column for aqueous SEC column.
Please refer to Corn Starch (1) (Aqueous Eluent) (SB-806M HQ).
Sample : Corn starch in DMSO
Column : Shodex OHpak SB-806 HQ (8.0mmI.D. x 300mm) Eluent : DMSO/DMF=75/25 5mM LiBr in DMSO/DMF=75/25 Flow rate : 0.25mL/min Detector : Shodex RI Column temp. : 40°C