Hach DR/850 - Page 350

350
5.
Place an ampul cap
securely over the tip of
the ampul. Shake the
ampul for about 30
seconds. Wipe off any
liquid or fingerprints.
Note: A blue color will
form if phosphate is
present.
Note: Accuracy is not
affected by undissolved
powder.
6. Press:
TIMER ENTER
A two-minute reaction
period will begin.
Perform Steps 7-8
during this period.
Note: Use an 8-10 minute
reaction period if
determining total
phosphorus following the
acid-persulfate digestion.
7. Place the blank into
the cell holder. Tightly
cover the sample cell
with the instrument cap.
8. Press: ZERO
The cursor will move to
the right, then the
display will show:
0.00 mg/L PO4
Note: If Reagent Blank
Correction is on, the
display may flash “limit”.
See Section 1.
9. After the timer
beeps, place the
AccuVac ampul into the
cell holder. Tightly
cover the ampul with the
instrument cap.
10. Press: READ
The cursor will move to
the right, then the result
in mg/L phosphate
(PO
4
3-
) will be
displayed.
Note: Standard Adjust may
be performed using a
2.0-mg/L PO
4
3-
standard;
see Section 1.
:30
PHOSPHORUS, REACTIVE, continued