Hach DR/850, Procedures Manual, Page: 359 / 460

359
Method 8180
PHOSPHORUS, ACID HYDROLYZABLE
Hydrolysis to Orthophosphate Method
*
For water, wastewater, seawater
* 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: Wash all glassware
with 6 N hydrochloric acid.
Rinse with deionized water.
Do not use detergents
containing phosphate to
clean glassware.
2.
Add 2.0 mL of
5.25 N Sulfuric Acid
Solution.
Note: Use the 1-mL
calibrated dropper
provided.
3.
Place the flask (the
prepared sample) 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.
4.
Cool the hot
prepared sample to room
temperature.
30:00
minutes