Hach DR2400 - Page 685

Phosphorus, Total
Phosphorus, Total
PhosphorusTot_UniCell_Other_APD_Eng_Ody.fm Page 3 of 6
Interferences
The ions listed in the following table have been individually tested up to the
given concentrations. Cumulative effects and the influence of other ions have
not been evaluated.
Sample Collection, Storage, and Preservation
Analyze samples within 3 hours after collection for best results. Store in a cool
dry place in plastic or glass bottles that have been acid cleaned with
1:1 Hydrochloric Acid Solution and rinsed with deionized water. Do not use
commercial detergents containing phosphate for cleaning glassware used in
this test.
For wastewater samples — If prompt analysis is impossible, preserve
samples
*
by adjusting the pH to 2 or less with Sulfuric Acid, 5.25 N
(Cat. No. 2449-00) and storing the sample at 4 °C for up to 28 days. The pH can
be checked using pH paper (Cat. No. 391-33). Do not use mercury compounds
as preservatives. Warm samples to room temperature before analysis.
Accuracy Check
Standard Additions Method (Sample Spike)
1. Clean glassware with 1:1 Hydrochloric Acid Standard Solution. Rinse again
with deionized water. Do not use detergents containing phosphate to
clean glassware.
2. After reading test results, leave the sample cell (unspiked sample) in the
instrument. Verify the chemical form.
3. Touch
Options. Touch Standard Additions. A summary of the standard
additions procedure will appear.
4. Touch
OK to accept the default values for standard concentration, sample
volume, and spike volumes. Touch
Edit to change these values. After values
are accepted, the unspiked sample reading will appear in the top row. See
Standard Additions in the instrument manual for more information.
5. Snap the neck off a 10-mL Voluette
®
Ampule of Phosphate Standard Solution,
500-mg/L as PO
4
3–
.
Interfering Substance No interference up to:
SO
4
2–
5000 mg/L
Cl
–
2000 mg/L
K
+
, Na
+
, Ca
2+
1000 mg/L
Mg
2+
, NO
3
–
500 mg/L
Co
2+
, Fe
2+
, Fe
3+
, Zn
2+
, Cu
2+
, Ni
2+
, Cr
3+
, I
–
,
NO
2
–
, Cd
2+
, Sn
2+
, NH
4
+
, Mn
2+
, Al
3+
, Hg
2+
,
Pb
2+
, SiO
2
50 mg/L
Ag
+
25 mg/L
Cr
6+
5 mg/L
* See 40 CFR 136.3