Hach DR/700 Procedures Manual page 443

PHOSPHORUS, TOTAL,
continued
7.
Pour the sample
into a 25-mL
graduated cylinder.
Using demineralized
water rinsings from
the flask, return the
volume in the cylinder
to 25 mL. Proceed
with a reactive
phosphorus test of the
expected total
phosphorus
concentration range.
Note: Results of the
reactive phosphorus test
at this point will include
the organic phosphate
plus the orthophosphate
and the acid hydrolyzable
(condensed) phosphate.
The organic phosphate
concentration is
determined by
subtracting the results of
an acid hydrolyzable
phosphorus test from this
result. Make sure that
both results are in the
same units, either mg/L
3-
PO or mg/L P before
4
taking the difference.
52-117