Hach DR/700 - Page 718

81-44
PHOSPHORUS, ACID HYDROLYZABLE, continued
4. Cool the prepared
sample to room
temperature.
5. Add 2.0 mL of
5.0 N Sodium
Hydroxide Solution.
Swirl to mix.
Note: Use the 1-mL
calibrated dropper
provided.
6. Pour the prepared
sample into a
graduated cylinder.
Add demineralized
water rinsings from
the flask to return the
volume to 25 mL.
Proceed with the
appropriate reactive
phosphorus test.
Note: Results of the
reactive phosphorus test
at this point will include
the orthophosphate plus
the acid-hydrolyzable
(condensed) phosphate.
The condensed
phosphate
concentration is
determined by
subtracting the results
of a reactive
phosphorus test on an
untreated sample from
this result.