Hach DR/700 Procedures Manual page 231

SULFATE,
13.
Place the
prepared sample in
the cell holder.
Note: In bright sunlight
it may be necessary to
close the cell
compartment cover.
SAMPLING AND STORAGE
Collect samples in clean plastic or glass bottles. Samples may be stored
up to 7 days by cooling to 4 °C (39 °F) or lower. Warm to room
temperature before analysis.
ACCURACY CHECK
Standard Additions Method
a) Snap the neck off a Sulfate Voluette Ampule Standard Solution,
2500 mg/L.
b) Use a TenSette Pipet to add 0.1, 0.2 and 0.3 mL of standard to three
25-mL samples. Mix thoroughly. For AccuVac ampuls, use 50-mL
beakers.
c) Analyze each sample as described above. The sulfate concentration
should increase 10 mg/L for each 0.1 mL of standard added.
d) If these increases do not occur, see Standard Additions (Section I) for
more information.
CALIBRATION
A new calibration is necessary when different manufacturing lots of
SulfaVer 4 powder Pillows or AccuVacs are used. A new calibration is
continued
14.
Within five
minutes after the five-
minute waiting
period, press:
The display will
count down to 0.
Then the display will
show the results in
mg/L sulfate (SO
READ
2-
).
4
45-59