Hach DR2400 - Page 637

Phosphorus, Reactive
Phosphorus, Reactive
PhosphorusReac_PT_High_MOL_Eng_Ody.fm Page 3 of 6
Interferences
The following do not interfere in concentrations up to 1000 mg/L:
Interfering Substance Interference Levels and Treatments
Arsenate Negative interference. Positive interference if sample is heated.
Bismuth Negative interference.
Fluoride Negative interference.
Iron, Ferrous
Blue color is caused by ferrous iron but this does not affect results if the ferrous iron
concentration is less than 100 mg/L.
Molybdate Negative interference.
Silica Positive interference if sample is heated.
Sulfide
Negative interference. Sulfide interference may be removed by oxidation with Bromine Water as
follows:
1. Measure 25 mL of sample into a flask.
2. Add Bromine Water (Cat. No. 2211-20) drop-wise with constant swirling until permanent
yellow color develops.
3. Add Phenol Solution (Cat. No. 2112-20) drop-wise until the yellow color just disappears.
Proceed with step 7.
Thiocyanate Negative interference.
Thiosulfate Negative interference.
Thorium Negative interference.
Highly buffered samples or
extreme sample pH
May exceed the buffering capacity of the reagents and require sample pretreatment; see Section
3.3 Interferences on page 41.
Pyrophosphate Tetraborate selenate Benzoate
Citrate Lactate Formate
Oxalate Tartrate Salicylate
Al
3+
Fe
3+
Mg
2+
Ca
2+
Ba
2+
Sr
2+
Li
+
Na
+
K
+
NH
4+
Cd
2+
Mn
2+
NO
3
–
NO
2
–
SO
4
2–
SO
3
2–
Pb
2+
Hg
+
Hg
2+
Sn
2+
Cu
2+
Ni
2+
Ag
+
U
Zr
4+
AsO
3
–
Br
–
CO
3
2–
ClO
4
–
CN
–
IO
3
–
SiO
4
4–