Synthesis and characterisation of starch phosphates

Monostarch monophosphates with different phosphorus contents were prepared via reacting starch with a mixture of primary and secondary sodium phosphates under weak acidic conditions in a semi-dry process. For a structural characterisation of starch phosphates P-31 NMR and FT Raman spectra were recorded. The degrees of substitution (DSp) of modified starch were determined using a standard wet chemistry method. By recording the FT Raman spectra of starch phosphates a characteristic band at similar to 975 cm(-1) was found whose intensity depends on the degree of phosphorylation of starch. The integrated areas of this C-O-P stretching vibration were plotted versus the degree of substitution DSp of starch phosphates obtained from standard photometric method. A strong linear correlation was derived which is suitable to determine the level of phosphorylation of starch phosphates with unknown DSp value by Raman spectroscopy as a rapid and non-destructive method. (C) 2010 Elsevier Ltd. All rights reserved.