Hach DR2400 Manual page 627

5.
When the timer
beeps, place the blank
into the cell holder.
Interferences
Interfering
Substance
Arsenate Only interferes if sample is heated.
Iron, ferrous Blue color caused by ferrous iron does not interfere if concentration is less than 100 mg/L.
Molybdate Causes negative interference above 1000 mg/L.
Silica Only interferes if sample is heated.
Causes a negative interference.
1. Measure 50 mL of sample into an Erlenmeyer flask.
2. Add Bromine Water (Cat. No. 2211-20) drop-wise with constant swirling until a permanent yellow color
Sulfide
develops.
3. Add Phenol Solution (Cat. No. 2112-20) drop-wise until the yellow color just disappears. Proceed with
step 3 (step 2 if using AccuVac procedure).
pH, extreme or
May exceed buffering capacity of reagents. See Section 3.3 Interferences on page 41. May require
highly buffered
pretreatment. pH should be about 7.
samples
Fluoride, thorium,
bismuth, thiosulfate Cause negative interference.
or thiocyanate
PhosphorusReac_AccuVac_Other_MOL_Eng_Ody.fm
Phosphorus, Reactive (Orthophosphate)
Zero
6.
Touch .
Zero
The display will show:
3–
0.0 mg/L PO
4
Table 1 Interfering Substances and Suggested Treatments
Interference Levels and Treatments
7.
Place the prepared
sample into the cell
holder.
Phosphorus, Reactive (Orthophosphate)
Read
8.
Touch .
Read
Results will appear in
3–
mg/L PO .
4
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