Why are the results using the GGA BOD standard catalog number 1486510, following the dilution method, twice as high as those reported in Standard Methods?

Document ID

Document ID TE168

Published Date

Published Date 27/05/2017
Question
Why are the results using the GGA BOD standard catalog number 1486510, following the dilution method, twice as high as those reported in Standard Methods?
Summary
Glucose Glutamic Acid (GGA) standard preparation and results
Answer
The Standard Methods result of 198 (+/- 30) mg/L BOD is based on standards containing 150 mg/L each of glucose and glutamic acid, which is half the concentration of the Hach BOD standard. The Hach BOD standard solution (Catalog No. 1486510) contains 300 mg/L each of glucose and glutamic acid. Therefore when using the Hach BOD standard the results are expected to be twice as high; divide results by 2 for comparison with Standard Methods.