27
METHOD PROCEDURE
INTERFERENCES
Interference may be caused by:
• Bromine, Iodine, Oxidized forms of Chromium and Manganese, Ozone
• Hardness greater than 500 mg/L CaCO
3
, to remove the interference shake the
sample for approximately 2 minutes after adding the powder reagent
• Alkalinity greater than 250 mg/L CaCO
3
or acidity value greater than 150 mg/L
CaCO
3
, the color of the sample may develop only partially or rapidly fade, to remove
the interference neutralize the sample with diluted HCl or NaOH