Determination of the amylose–amylopectin ratio of starches by iodine-affinity capillary electrophoresis

This paper describes the application of capillary electrophoresis to separate and quantify the main polysaccharide components, amylose and amylopectin, present in starch samples. The separation is based on the well-known affinity of these compounds to iodine. The starch components could be effectively separated in less than 7 min using an uncoated fused-silica ‘bubble cell’ capillary. The proposed method has been applied for the quantitative determination of the soluble amylose content and the ratio amylose–amylopectin in commercial starches. It is shown that the present method is reliable, gives detection limits in the order of 0.1 mg mL−1, is faster than other methodologies reported in the literature, and can be easily applied to the analysis of different starches. In spite of differences in solubility of amylopectin from different sources, a reasonable estimate of the amylose–amylopectin ratio could be made. Additionally, it was shown that the resulting profiles obtained after hydrolysis with isoamylase and α-amylase can provide information on the structure of the starches studied.