Is there a way to remove ferrous iron interference in Hach Tannin and Lignin Method 8193?

Document ID

Document ID TE1702

Published Date

Published Date 27/05/2017
Question
Is there a way to remove ferrous iron interference in Hach Tannin and Lignin Method 8193?
Summary
Removing ferrous iron interference from Hach Method 8193
Answer
Ferrous iron causes a positive interference (2 mg/L of ferrous iron produces a color equivalent to about 1 mg/L of tannic acid). To remove interference of ferrous iron up to 20 mg/L, add one 0.2 g scoop of Sodium Pyrophosphate (catalog number 1429525) to the sample before the test.