For post-column organic acids analysis method, the eluent (eluate) eluted from a column is mixed with a reaction reagent solution (contains pH indicator) in a mixing module. When organic acids are present in the eluate, the pH indicator changes its color. This color change is detected by a visible detector (430 nm).
Below explains how to prepare 10-hold concentrated reaction reagent solution.

Preparation steps

1. (1)Prepare “Solution 1” by adding 28.65 g of disodium hydrogen phosphate dodecahydrate to 900 g of water. Stir until completely dissolved.
2. (2)Prepare IPA aqueous solution by mixing 25 mL of 2-propanol (IPA) and 25 mL of water. Then prepare “Solution 2” by adding 1.08 g of bromcresol purple to the IPA aqueous solution. Stir while applying ultrasound until dissolved.
3. (3)Set aside about 50 mL of "Solution 1" in another container. While stirring, add the entire amount of "Solution 2" to the remaining "Solution 1".
4. (4)Rinse the container of "Solution 2" with 50 mL of "Solution 1" set aside. Add it to (3).
5. (5)Add 0.5 g of thorium azide to (4) and stir. Obtained is the 10-fold concentrated solution.

How to use

Dilute the 10-hold concentrated solution 10 times (1+9) with water and use it as the reaction reagent.

How to store

Store the 10-hold concentrated solution in a light-shielding glass container at or below 25 ℃.