Hach DR/700 - Page 708

81-34
PHOSPHORUS, TOTAL, continued
4. After 2 seconds,
the display will show
a program number,
the concentration
units and the zero
prompt. Press the
PROGRAM key until
the lower display
shows program
number
81.000
The upper display
will show the S1
concentration.
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.
6. Add 2 mL of
1.00 N H
2
SO
4
to the
sample vial.
Note: A 2-mL Repipet
and 1 liter bottle of
sulfuric acid(1270-53)
can be used for
convenience when
analyzing multiple
samples.
7. Using a funnel,
add the contents of
one Potassium
Persulfate Powder
Pillow for
Phosphonate to the
vial.
8. Cap tightly and
shake to mix.
9. Heat the vial for
30 minutes.