Hach DR/850, Procedures Manual, Page: 355 / 460

355
Method 8190
PHOSPHORUS, TOTAL
For water, wastewater, and seawater
(Also called Organic and Acid Hydrolyzable) Acid Persulfate Digestion Method
*
USEPA Accepted for reporting wastewater analysis
**
* Adapted from Standard Methods for the Examination of Water and Wastewater.
1.
Measure 25 mL of
sample into a 50-mL
erlenmeyer flask using a
graduated cylinder.
Note: Rinse all glassware
with 1:1 Hydrochloric Acid
Solution. Rinse again with
deionized water. Do not use
detergents containing
phosphates to clean
glassware.
Note: Adjust the pH of
stored samples
before digestion.
2.
Add the contents of
one Potassium Persulfate
Powder Pillow. Swirl to
mix.
3.
Add 2.0 mL of
5.25 N Sulfuric
Acid Solution.
Note: Use the 1-mL
calibrated
dropper provided.
4.
Place the flask on a
hot plate. Boil gently for
30 minutes.
Note: Samples should be
concentrated to less than
20 mL for best recovery.
After concentration,
maintain the volume near
20 mL by adding small
amounts of deionized water.
Do not exceed 20 mL.
** Procedure is equivalent to USEPA Method 365.2 and Standard Method 4500-P B,5 & P E.
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