Hach DR/850 - Page 348

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5.
Press:
TIMER ENTER
A two-minute reaction
period will begin.
Perform Steps 6-8
during this period.
Note: If the acid-persulfate
digestion was used, an 8-10
minute reaction period is
required.
6. Fill another sample
cell with 10 mL of
sample (the blank).
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
prepared sample into the
cell holder. Tightly
cover the sample cell
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.
PHOSPHORUS, REACTIVE, continued