AOAC SPDS Mid Year 2016
Existing Methods • Colorimetric Assay by Red Dye – Alizarin Red
– Gu et al ., Binding interaction between aloe polysaccharide and alizarin red by spectrophotometry and its analytical application. Carbohydrate Polymers. 2010 , 80 , 115–122.
O OH
OH
+
Aloe polysaccharides
- Na +
SO 3
O alizarin red
• Complex of alizarin red with polysaccharides and assayed at 325nm and 516nm
Existing Methods • Colorimetric Assay of Acetyl Groups of Polysaccharides – Aloe Products for Food Raw Material, Chinese National Standard, QB/T 2489 2007
O O Fe /3
O
O
1/3Fe 3+
NH 2 OH
OH
R
N H
N H
O
Ferric - Acethydroxamic Acid Complex
Acetohydroxamic Acid
Th t l • e ace y groups on po ysacc ar es are reac e w hydroxylamine to form acetohydroxamic acid. The resulted acetohydroxamic acid is reacted with ferric trichloride to form a ferric‐acethydroxamic acid complex and measured 540nm. l h id t d ith
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