Hach DR/850, Procedures Manual, Page: 414 / 460

414
Sampling and Storage
Collect samples in clean plastic or glass bottles. Fill completely
and cap tightly. Avoid excessive agitation or prolonged exposure
to air. Analyze samples immediately.
Accuracy Check
Sulfide standards are unstable and must be user prepared. See
Sandard Methods, 4500S
– for preparation and standardization
directions.
Method Performance
Precision
In a single laboratory, using standard solutions of 0.73 mg/L
sulfide and two representative lots of reagent with the instrument,
a single operator obtained a standard deviation of ± 0.02 mg/L
sulfide.
Estimated Detection Limit (EDL)
The EDL for program 93 is 0.01 mg/L S
2-
. For more information
on derivation and use of Hach’s estimated detection limit, see
Section 1 .
9.
Press:
ZERO
The cursor will move to
the right, then the
display will show:
0.00 mg/L S
10.
After the timer
beeps, place the
prepared sample into the
cell holder. Tightly
cover the sample cell
with the instrument cap.
11.
Press:
READ
The cursor will move to
the right, then the result
in mg/L sulfide will be
displayed.
Note: Some sulfide loss
may occur if dilution is
necessary.
Note: Standard Adjust may
be performed using a
prepared standard (see
Standard Adjust in
Section 1).
SULFIDE,
continued