LaMotte COD Plus Colorimeter 1922-EX2 - Manual (Page 91)

INTERFERENCES: The following substances produce a positive interference at
the concentration given:
Chloride (Cl–)
7000 mg/L
Phosphate (PO
4
–3 ) 16 mg/L
Hexametaphophate (NaPO
3
)
6
1 mg/L
The following substances produce a negative interference at
the concentration given:
Alkalinity (CaCO
3
) 5000 mg/L
Aluminum (Al 3+ ) 0.1 mg/L
Iron (Fe 3+ ) 10 mg/L
Sulfate (SO
4
–2 ) 200 mg/L
Color and turbidity must be removed or compensated for in
the procedure. Temperature should be maintained within
5°C of room temperature.
FLUORIDE 2/3 COD PLUS TEST PROCEDURES 6/02