Starch is used for a variety of industrial and nutritional purposes. Its functional properties are influenced by the ratio and molar masses of its macromolecular constituents, which vary with source, crop year, and climate. Starch contains large homopolymers of amylose (AMY) and amylopectin (AMP).
Linear AMY consists of long chains of (1→4)-ɑ-D-glucose linkages, while the higher-molar-mass AMP is a branched structure containing a mixture of (1→4)-ɑ- and (1→6)-ɑ-D-glucose linked residues. With average radii in the hundreds of nm, and molecular weights ranging into the hundreds of millions, starch polymeric components cannot be separated by GPC. However, asymmetric-flow field-flow fractionation coupled to multi-angle light scattering (AF4-MALS) is suitable for separation and characterization of polymers and nanoparticles from 1 nm to 1000 nm and hence is applicable to starch analysis. AF4 performs non-shearing separation by hydrodynamic size, and MALS analyzes absolute molar mass and size regardless of conformation or retention properties.
