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A Comparison of Some Methods for the Determination of the Degree of Substitution of Carboxymethyl Starch
Author(s) -
Stojanović Željko,
Jeremić Katarina,
Jovanović Slobodan,
Lechner M. Dieter
Publication year - 2005
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.200400342
Subject(s) - titration , starch , chemistry , potato starch , precipitation , maize starch , corn starch , degree (music) , salt (chemistry) , acid–base titration , chromatography , food science , organic chemistry , physics , meteorology , acoustics
The degree of substitution (DS) markedly affects the properties of sodium carboxymethyl starch (Na‐CMS). In this work Na‐CMS samples with different DS starting from both potato and corn starch were synthesized in an ethanol/water mixture and their DS was determined using three methods: direct titration of the acid form of the carboxymethyl starch (H‐CMS), Cu salt precipitation and back titration. It was found that direct titration gave smaller DS values, while the Cu salt precipitation method gave higher DS values than the back titration method, which was found to be the most accurate. The values of the DS obtained by these methods were similar for lower DS while for higher values the discrepancy was more pronounced. Under the same experimental conditions the CMS obtained from corn starch had a higher DS than the one obtained from potato starch and on average, the discrepancies between the DS values obtained by the employed analytical methods were smaller for the CMS samples synthesized from corn starch.