Hach DR/700 Procedures Manual page 110

NICKEL,
continued
13.
Repeat Steps 6
to 8 and Step 12 two
additional times with
10-mL portions of
chloroform. Drain
the chloroform layer
into the same sample
cell.
Note: The five-minute
reaction period is not
necessary for the second
and third extractions.
Shake with chloroform;
wait for layers to
separate, then continue.
Note: The final volume
of extract will be about
25 mL due to the slight
solubility of chloroform
in water. Use all the
chloroform extracted,
exact final volume is not
important.
Note: Swirl sample cell
to mix extracts.
14.
Fill a second
sample cell with
chloroform (the
blank). Place the
blank in the cell
holder.
Note: Typical indoor
lighting permits the
DR/700 to operate with
the cell compartment
cover open, In bright
sunlight, it may be
necessary to close the
cell compartment cover.
Transfer 10 mL of the
blank solution to a
10-mL cell. If a 10-mL
cell is used for the blank
a 10-mL cell must also
be used for the sample.
42-26
15.
Press:
ZERO
The display will
count down to 0.
Then the display will
show 0.00 mg/L and
the zero prompt will
turn off.