58
Start by adding 500 µL at a time (for example). Watch the change in mV. When you have
observed approximately a 15 mV change from the original sample, calculate the total volume
added. Adjust sample and standard volumes proportionally to standard volumes that can be
measured with accuracy. Use volumetric pipettes for standard, ISA and sample addition.
• Press
: Edit the procedure variables to the volumes determined in the prior step.
Procedure:
• Press
to enter Known Addition mode.
• Volumetrically add sample to a clean beaker. Add a magnetic stir bar and place on a stir plate.
Stir sample. The method will prompt user to add ISA. Place ISE sensor tip into the solution and
a mV value will show on the display.
• Press
to take the first mV reading.
• When the reading is stable, press
to store the first mV reading. The second step of
the method will be displayed on the LCD in which the user is notified to add the Volume of
Standard to the sample.
• Press
to take the second mV reading.
• When the reading is stable, press
to store
the second mV reading. The ISE measurement results
will be displayed on the LCD.
• Press
to log the current results into a ISE
Method Report. Press
to return to ISE
Measure mode. Press
to measure additional
samples. Rinse ISE sample between samples.
• Press
to modify the method parameters.
Note: Press
at any time to stop the
measurement and return to ISE Measure mode.
KNOWN SUBTRACTION
To measure the concentration of a sample using the Known Subtraction method:
• Press
and then
to select
ISE Measure
mode for the selected channel.
• Select the Known Subtraction method (see ISE Setup
→
Reading Mode).
• Prior to starting a KS procedure, the ISE sensor must be calibrated with a minimum of two
standards containing ISA. The slope of the electrode will be used in all calculations involved in
KS.
ISE MEASUREMENT (HI5222 only)
