Hach DR/850 - SULFIDE, Methylene Blue Method

413
Method 8131
SULFIDE (0 to 0.70 mg/L S
2-
) For water, wastewater and seawater
Methylene Blue Method
*
USEPA accepted for reporting wastewater analysis
**
* Adapted from Standard Methods for the Examination of Water and Wastewater.
1. Enter the stored
program number for
sulfide (S).
Press:
PRGM
The display will show:
PRGM ?
2. Press: 93 ENTER
The display will show
mg/L, S and the
ZERO icon.
3. Pipet 25 mL of
sample into a clean
sample cell. This will be
the prepared sample.
Note: Samples must be
analyzed immediately and
cannot be preserved for
later analysis. Use a pipet
to avoid agitation.
Note: For field testing, a
25-mL graduated cylinder
may be used.
4. Fill a second sample
cell with 25 mL of
deionized water
(the blank).
5. Add 1.0 mL of
Sulfide 1 Reagent to
each cell. Swirl to mix.
Note: Use the calibrated
1-mL dropper.
6. Add 1.0 mL of
Sulfide 2 Reagent to
each cell. Immediately
swirl to mix.
Note: A pink color will
develop, then the solution
will turn blue if sulfide
is present.
7. Press:
TIMER ENTER
A 5-minute reaction
period will begin.
8. Place the blank into
the cell holder. Tightly
cover the sample cell
with the instrument cap.
** Procedure is equivalent to USEPA method 376.2 or Standard Method 4500-S
2-
D for wastewater.