Determination of Degree of Substitution of Extruded Benzylated Starch by H‐NMR and UV Spectrometry

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Abstract
A quantitative method for the determination of the degree of substitution (DS) of extruded benzylated starch is developed (DS = 0.01 – 0.40). Sample pretreatment by freezing the product in liquid nitrogen and a methanol extraction of the reaction components (e. g. benzyl chloride, benzyl alcohol) is described. Aqueous formic acid solutions of the starch products were analyzed both with UV analysis (λ = 259 nm.) and with a NMR “coaxial tubing” analysis technique. Both techniques showed similar results with good correlation and a standard deviation < 0.01 DS.