Phosphorus, Reactive (Orthophosphate)
Phosphorus, Reactive (Orthophosphate)
Page 4 of 6
PhosphorusReac_AVPP_Other_PV3_Eng_Ody.fm
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. The sample should be at room temperature before analysis.
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. Open a Phosphate 10-mL Ampule Standard, 50-mg/L PO
4
3–
.
5. Prepare a 0.1-mL sample spike by adding 0.1 mL of standard to the unspiked
sample. Touch the timer icon. After the timer beeps, read the result.
6. Prepare a 0.2-mL sample spike by adding 0.1 mL of standard to the 0.1-mL
sample spike. Touch the timer icon. After the timer beeps, read the result.
7. Prepare a 0.3-mL sample spike by adding 0.1 mL of standard to the 0.2-mL
sample spike. Touch the timer icon. After the timer beeps, read the result.
Each addition should reflect approximately 100% recovery.
Note: For AccuVac ampules, fill three Mixing Cylinders (Cat. No. 1896-41) with 50 mL of sample
and spike with 0.2 mL, 0.4 mL, and 0.6 mL of standard. Transfer 40 mL from each of the
three mixing cylinders to three 50-mL Beakers (Cat. No. 500-41H). Analyze each standard
addition sample as described in the procedure above. Accept each standard additions
reading by touching Read. Each addition should reflect approximately 100% recovery.
8. 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. Use a 1.0-mg/L phosphate standard solution in place of the sample. Perform
the procedure as describe above.
2. To adjust the calibration curve using the reading obtained with the
1.0-mg/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.
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