Phosphorus, Reactive
Phosphorus, Reactive
Page 4 of 6
PhosphorusReac_PT_High_MOL_Eng_Ody.fm
Sampling and Storage
Collect samples in clean plastic or glass bottles that have been cleaned with
1:1 Hydrochloric Acid Solution (Cat. No. 884-49) and rinsed with deionized
water. Do not use detergents that contain phosphate for cleaning labware.
Analyze samples immediately for best results. If prompt analysis is not possible,
preserve samples by filtering immediately and storing the sample at 4 °C (39 °F)
or below for up to 48 hours. Warm to room temperature before analyzing.
Treating Analysis Labware
Clean containers by normal means (do not use detergents containing
phosphorus), then rinse with deionized water. Soak for several minutes in a
1:25 dilution of Molybdovanadate Reagent in deionized water. Rinse well with
deionized water. Dedicate these containers for HR PO
4
3–
analysis. Fill the
Pour-Thru Cell with this same mixture of Molybdovanadate reagent and
deionized water, and let stand for several minutes. Rinse with 50 mL of
deionized water.
Cleaning the Pour-Thru Cell
The Pour-Thru Cell may accumulate a buildup of colored products, especially if
the reacted solutions are allowed to stand in the cell for long periods after
measurement. Remove the color by rinsing with a 1:5 dilution of ammonium
hydroxide (Cat. No. 106-49), followed by several deionized water rinses. Invert a
beaker over the glass funnel of the Pour-Thru Cell when not in use.
Accuracy Check
Standard Additions Method (Sample Spike)
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument. Verify the chemical form.
2. Touch
Options. Touch Standard Additions. A summary of the standard
additions procedure will appear.
3. 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.
4. Snap the neck off a Phosphate Voluette
®
Ampule Standard Solution,
500-mg/L as PO
4
3–
.
5. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-40)
with 25 mL of sample. Use the TenSette Pipet to add 0.1 mL, 0.2 mL, and
0.3 mL of standard, respectively, to each sample and mix thoroughly.
6. Analyze each sample spike as described in the procedure above, starting with
the 0.1 mL sample spike. Accept each standard additions reading by touching
Read. Each addition should reflect approximately 100% recovery. Each 0.1-mL
addition of standard should cause an increase of 2.0 mg/L PO
4
3–
or 0.65 mg/
L P.
7. After completing the sequence, touch
Graph to view the best-fit line through
the standard additions data points, accounting for matrix interferences. Touch
View: Fit, then select Ideal Line and touch OK to view the relationship between
the sample spikes and the “Ideal Line” of 100% recovery.
See Section 3.2.2 Standard Additions on page 32 for more information.
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