Phosphorus, Reactive
Phosphorus, Reactive
Page 4 of 6
PhosphorusReac_PT_Low_ASC_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 at 4 °C (39 °F) for up to
48 hours.
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 Standard Solution Ampule, either 15-mg/L
(15,000 µg/L) as PO
4
3–
or 50-mg/L (50,000 µg/L) as PO
4
3–
. Use the 15-mg/L
standard when the phosphate concentration of samples is less than
1000 µg/L.
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.
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.
Standard Solution Method
1. Run the test using a 1000-µg/L (1.000-mg/L) phosphate standard solution in
place of the sample. Results should be 900 to 1100 µg/L phosphate.
2. To adjust the calibration curve using the reading obtained with the
1000-µg/L PO
4
3–
Phosphate Standard Solution, touch Options on the current
program menu. Touch
Standard Adjust.
3. Touch
On. Touch Adjust to accept the displayed concentration (the value
depends on the selected chemical form). If an alternate concentration is used,
touch the number in the box to enter the actual concentration, then touch
OK.
Touch
Adjust.
For more information, see Section 3.2.4 Adjusting the Standard Curve on page 40.
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