Low-level measurements – Hach-Lange ISEF12103 User Manual User Manual
Page 5
1. Connect the probe
to the meter. Make
sure that the cable
locking nut is securely
connected to the
meter. Turn the meter
on.
2. Prepare a
minimum of 25 mL of
the sample(s) in
beakers or
appropriate
containers. Add the
contents of one
Fluoride ionic strength
adjustment (ISA)
powder pillow per
25 mL to each
sample.
3. Rinse the probe
with deionized water.
Blot dry with a lint-free
cloth.
4. Add a stir bar and
put the probe in the
sample. Do not put
the probe on the
bottom or sides of the
container.
5. Put the beaker on
an electromagnetic
stirrer and stir at a
moderate rate. Check
for air bubbles and
remove them if
necessary.
6. Push Read. The
display will show
"Stabilizing" and a
progress bar as the
probe stabilizes in the
sample. The display
will show the lock icon
when the reading
stabilizes.
7. Repeat steps 2 - 6
for additional
measurements.
8. When
measurements are
done, store the probe
(refer to
on page 11).
Low-level measurements
Use the following techniques for measurements at low concentrations (<1 mg/L F
–
).
•
Use plastic containers during calibration and measurements. Glass containers can
cause inaccurate measurements.
•
Clean the probe regularly as specified in
•
Soak the probe in the lowest concentration standard solution for up to 1 hour before
calibration and measurement.
•
Set the stability criteria to a low value (refer to
on page 7).
•
Stir the standards and samples at a slow and steady rate to prevent the formation of
a vortex.
•
Use a dilute ionic strength adjustor (ISA) solution for calibration and measurements:
1. Dissolve the contents of one ionic strength adjustor powder pillow in 50 mL of
deionized water.
2. Add 5 mL of this solution to every 25 mL of standard or sample that is used.
Note: The ionic strength adjuster can be omitted only when all of the following conditions are
true:
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