Hach DR2400 - Page 632

Phosphorus, Reactive (Orthophosphate)
Phosphorus, Reactive (Orthophosphate)
Page 2 of 4
PhosphorusReac_TNT_High_MOL_Eng_Ody.fm
Interferences
5. Install the 16-mm
adapter.
Note: See Section 2.6 in the
Instrument Manual for
installation details.
When the timer beeps,
place the sample vial into
the adapter.
6. Touch Zero.
The display will show:
0.0 mg/L PO
4
3–
7. Place the sample vial
into the cell adapter.
8. Touch Read.
Results will appear in
mg/L PO
4
3–
.
Interfering
Substance
Interference Levels and Treatments
Arsenate Only interferes if the sample is heated.*
* Gentle warming of the sample to room temperature will not prevent this substance from interfering.
Iron, ferrous Blue color caused by ferrous iron does not interfere if iron concentration is less than 100 mg/L.
Molybdate Causes negative interference above 1000 mg/L.
Silica Only interferes if the sample is heated.*
Sulfide
Causes a negative interference. Remove interference as follows:
1. Measure 25 mL of sample into a 50-mL beaker.
2. Add Bromine Water (Cat. No. 2211-20) drop-wise with constant swirling until a permanent yellow
color develops.
3. Add Phenol Solution (Cat. No. 2112-20) drop-wise until the yellow color just disappears.
Proceed with step 1.
Extreme pH or highly
buffered samples
May exceed buffering capacity of the reagents. Samples may require pretreatment. Sample pH should
be about 7.
Fluoride, thorium,
bismuth, thiosulfate or
thiocyanate
Cause a negative interference.
Temperature, Cold
(less than 20 °C)
Causes a negative interference.
Temperature, Hot
(greater than 25 °C)
Causes a positive interference.
The following do not interfere in concentrations up to 1000 mg/L:
Pyrophosphate, tetraborate, selenate, benzoate, citrate, oxalate, lactate, tartrate, formate, 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
4+
, Zn
4+
,
AsO
3
–
, Br
–
, CO
3
2–
, ClO
4
–
, CN
–
, IO
3
–
, SiO
4
4–
.
Zero
Read