Phosphorus, Reactive (Orthophosphate)
Phosphorus, Reactive (Orthophosphate)
PhosphorusReac_TNT_High_MOL_Eng_Ody.fm Page 3 of 4
Sampling and Storage
Collect samples in 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 commercial detergents containing phosphate for cleaning
glassware used in this test.
For best results, analyze the samples immediately after collection. If prompt
analysis is impossible, preserve the samples for up to 48 hours by filtering
immediately and storing at 4 °C. The sample should be at room temperature
before analysis.
Accuracy Check
Standard Additions Method (Sample Spike)
1. Clean glassware with 1:1 hydrochloric acid 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 PO
4
3–
(Cat. No. 14242-10).
6. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-40)
with 10 mL of sample. Use the TenSette Pipet to add 0.1, 0.2 mL, and 0.3 mL of
standard, respectively to each sample and mix thoroughly.
7. 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.
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 50-mg/L PO
4
3–
standard in place of the sample. Perform this
procedure as described.
2. To adjust the calibration curve using the reading obtained with the
50-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.
For more information, see Section 3.2.4 Adjusting the Standard Curve on page 40.
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