Hach IntelliCAL ISENH3181 Series, User Manual

Page: 10 / 20

Section 6 Sample measurement
The procedure that follows is applicable to meters that can connect to Intellical ISE probes. Refer to
the applicable meter documentation for meter operation and probe-specific settings.
6.1 Sample measurement notes
Read the notes that follow before sample measurements.
• Make sure to install the ammonia membrane module with ammonia electrode filling solution on the
probe.
• Rinse the probe with deionized water and dry with a lint-free cloth between measurements to
prevent contamination.
• To measure samples of low concentration after measurements of high concentration, reset the
filling solution for best results. To reset the filling solution, put the probe (with installed membrane)
in a 1000 mg/L NH
3
—N standard solution without ISA for 30 seconds to 1 minute.
• If the stabilization time is long, try a different stir rate and make sure to condition the probe.
• Keep all of the solutions (standard solutions and samples) at the same temperature (± 2 °C
(± 3.6 °F)) for best results.
• If complete traceability is necessary, enter a sample ID and operator ID before measurement.
Refer to the meter manual for instructions.
• Stir the standards and samples at a slow and constant rate to prevent the formation of a vortex.
• The meter automatically saves the measurement data when the user manually reads each data
point and when the meter is set to read at regular intervals. The user must manually save each
data point when the meter is set to read continuously.
• Air bubbles below the sensor can cause a slow response or error in the measurement. Make sure
to remove air bubbles before and during measurements.
6.2 Sample measurement procedure
1. Pour 25 mL of
fresh sample into a
50
‑
mL beaker.
2. Add one
Ammonia Ionic
Strength Adjustor
(ISA) Powder Pillow.
Note: As an alternative,
add 0.5 mL of Ammonia
ISA Solution.
3. Add a stir bar.
Put the beaker on an
electromagnetic
stirrer. Stir at a
moderate rate.
4. Rinse the probe
with deionized water.
Dry the probe with a
lint-free cloth.
8 English