Phosphorus, Reactive (Orthophosphate)
Phosphorus, Reactive (Orthophosphate)
PhosphorusReac_TNT_Other_PV3_Eng_Ody.fm Page 3 of 6
Sample Collection, Storage, and Preservation
Collect samples in plastic or glass bottles that have been acid 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.
Analyze samples immediately after collection for best results. If prompt analysis
is impossible, preserve samples up to 48 hours by filtering immediately and
storing at 4 °C. Warm samples to 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 phosphate detergents 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 Phosphate 2-mL Ampule Standard, 50-mg/L as PO
4
3–
.
6. Prepare three sample spikes. Use the TenSette Pipet to add 0.1 mL, 0.2 mL,
and 0.3 mL of standard, respectively to three 25-mL samples and mix each
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.
Silicate Greater than 10 mg/L
Sulfide
Greater than 6 mg/L. Remove sulfide interference as follows:
1. Measure 25 mL of sample into a 50-mL beaker.
2. Swirling constantly, add Bromine Water (Cat. No. 2211-20)
drop-wise until a permanent yellow color appears.
3. Swirling constantly, add Phenol Solution (Cat. No. 2112-20)
drop-wise just until the yellow color disappears. Proceed with
step 1 of the phosphorus procedure.
Tu rb i di ty
Large amounts may cause inconsistent results in the test
because the acid present in the powder pillows may dissolve
some of the suspended particles and because of variable
desorption of orthophosphate from the particles.
Zinc Greater than 80 mg/L
Highly buffered samples or
extreme sample pH
May exceed the buffering capacity of the reagents and require
sample pretreatment.
(continued)
Interfering Substance Interference Levels and Treatments (continued)
To Next Page
Loading...
