What can cause a blue color to develop after the addition of the DPD reagent?

Document ID

Document ID TE208

Published Date

Published Date 27/05/2017
Question
What can cause a blue color to develop after the addition of the DPD reagent?
Summary
Blue color after adding DPD
Answer
A blue color could be an indication that hydrogen sulfide is interfering with the DPD chemistry. It is recommended to dilute the sample and retest, mulitiplying your result by the dilution factor utilized.