Hach DR/700 Procedures Manual page 690

PHOSPHORUS, ACID HYDROLYZABLE,
4.
After 2 seconds,
the display will show
a program number,
the concentration
units and the zero
prompt. Press the
key until
PROGRAM
the lower display
shows program
number
81.000
The upper display
will show the S1
concentration.
7.
Cap tightly and
shake to mix.
5.
Fill a Test 'N
Tube Cuvette vial
with 5 mL of sample.
Note: For proof of
accuracy, use a 1.0 mg/L
Phosphorus as
phosphate (0.33 mg/L P)
Standard Solution (see
Optional Reagents) in
place of the sample.
Note: Run a reagent
blank for this test. Use
demineralized water in
place of the sample.
Subtract this result from
all test results run with
this lot of PhosVer 3.
8.
Heat the vial for
30 minutes.
81-16
continued
6.
Add 2 mL of
1.00 N H SO to the
2 4
sample vial.
Note: A 2-mL Repipet
and 1 liter bottle of
H SO (1270-53) can be
2 4
used for convenience
when analyzing multiple
samples.
9.
Carefully remove
the vial from the
reactor. Place it in a
test tube rack and
allow to cool to room
temperature.
Note: Tubes will be hot.