Why are the results using the Hach glucose and glutamic acid (GGA) standard solution catalog number 1486510 lower for CBOD than for BOD?

Document ID

Document ID TE170

Published Date

Published Date 27/05/2017
Question
Why are the results using the Hach glucose and glutamic acid (GGA) standard solution catalog number 1486510 lower for CBOD than for BOD?
Summary
Differences between BOD and CBOD results using GGA standard catalog number 1486510
Answer
It is common for the results of CBOD to be lower using GGA standards, but the reason for this phenomenon is not well understood. It appears that the nitrification inhibitor has an adverse effect on the seed, possibly due to nitrifying bacteria in the seed. Increasing the amount of seed in each bottle normally improves results and brings a closer correlation between BOD and CBOD.