Simple purification (Desalting) procedure to facilitate structural analysis of an alkali-solubilized/neutralized starch solution by intermediate-pressure size-exclusion chromatography

A technique was established to remove impurities (e.g., salts) from starch dissolved in strong alkali and neutralized with acid to accommodate starch structural analysis via intermediate-pressure size-exclusion chromatography (IPSEC). Starch (corn and wheat) subjected to an alkaline-microwave dissolution scheme (35 s microwave heating in a mixture of 6 M urea and 1 M KOH) was either treated with ion-exchange resin or passed through a desalting column to remove salt/urea contaminants. Control (untreated) starch solution analyzed by IPSEC displayed a significant interfering peak (attributable to salt/urea), which coeluted with the starch amylose peak. The interfering peak was most efficiently eliminated by first passing the starch solution through a desalting column, which process effectively removed impurities (e.g., salts/urea) without appearing to adversely impact the starch structural analysis. This simple technique coupled with the rapid alkaline-microwave starch dissolution procedure greatly expedites structural investigation of starch by facilitating analysis by IPSEC.