How does one use Allylthiourea (ATU) for CBOD?

Document ID

Document ID TE182

Published Date

Published Date 09/01/2020
How does one use Allylthiourea (ATU) for CBOD?
Allylthiourea (ATU) for CBOD analysis
Allylthiourea (ATU) is a nitrification inhibitor mentioned in the 22nd edition of Standard Methods for measuring Carbonaceous Biochemical Oxygen Demand (CBOD). Standard Methods mentions that ATU may not work as well as 2-chloro-6-(trichloromethyl) pyridine (TCMP), which is contained in the formulations of Hach nitrification inhibitor. Furthermore, ATU concentrations above 2 mg/L will cause high results.

To use ATU:

1. Dissolve 2 g of ATU into 1 L of water.
2. Mix and store at 4 °C. The solution is stable for not more than 2 weeks.
3. Add 0.3 mL of this solution to each 300 mL BOD bottle. Do not add ATU to the BOD bottles until they are at least two-thirds filed with diluted sample.


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