Post-column Method of Organic Acids
The post-column method of organic acids uses the reagent (Shodex ST3-R), the
mixing module and the visible detector of 430nm wave length . The detector detects
the color which comes from organic acids. Organic acids in a sample are separated
by the column for organic acid analysis (RSpak
KC-811) using acidic solution (ex. perchloric acid) as the eluent. The pH indicator
in the reagent (ST3-R) is adjusted to be dissociated state (I
-+H
+).
When the pH indicator and the eluted solution from the column are mixed in the
mixing module, the acidic substances (organic acids) will be free state (AH->A
-+H
+)
and the pH indicator generate color by the reaction of I
-+H
+->IH.
Right figure shows the spectrum of the pH indicator.
