23
To set one of the Temperature options:
• Press
while in
pH Measure
mode.
• Press
.
• Use
or
to select the Temperature option.
• Press
and use
or
to highlight the
desired Temperature option you wish to modify.
• Press
and use
or
to highlight the
desired option (for Temperature Source & Unit options) or use
or
to adjust the temperature value between
the displayed limits (for Manual Temperature option).
• Press
to confirm your selection (for Temperature Source
& Unit options) or press
to save the current value (for Manual Temperature option). Otherwise, press
to cancel operation.
Calibration
This option allows the user to setup desired buffers and calibration reminder.
Buffer Entry Type
Three settings are available for the pH buffers used for electrode calibration:
Automatic
- the instrument automatically selects the closest buffer to the measured pH value from the
predefined buffers chosen in the option
Edit Buffer Group
.
Semiautomatic
- the instrument automatically selects the closest buffers to the measured pH value from all
available buffers and you can choose the one used to be, from standard and custom buffers.
Manual Selection
- the desired pH buffer is manually selected from all available buffers (standard and
custom).
To set the Buffer Entry Type:
• Press
while in
pH Measure
mode.
• Press
.
• Use
or
to select the Calibration option.
• Press
and use
or
to highlight the
Buffer Entry Type option.
• Press
and use
or
to highlight the
desired option.
• Press
to confirm your selection or press
to
cancel operation.
58
• Press
to set the method parameters. Press
/
to select next/previous parameter
to edit, then press
and use
or
to set the desired parameter value. Press
to save the modified value and then press
to exit method parameters edit menu.
• If developing a procedure: Before attempting Analyte Addition analysis, it is important to determine
which standard volume, concentration and sample size will produce the best results. As a general rule,
the standard must be less concentrated than the sample so the addition of sample will increase the total
Ion content of the beaker and change the mV value by at least 10 mV. For a positively charged Ion (i.e.
Sodium), the AA increases the mV. For a negatively charged Ion (i.e. Sulfide, Fluoride, Chloride), the AA
should decrease the mV. Start with a small trial. For example: Measure 50 mL of standard, add a
magnetic stir bar and place on a stirrer, add ISA (consult ISE manual) and place ISE electrode tip into the
sample. Put instrument in mV mode and record the observed mV. Using a micropipet, add a volume of
the sample. Start by adding 500 µL at a time (for example). Watch the change in mV. When you have
observed approximately a 10 mV change from the original standard, 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
then edit the procedure variables to the volumes determined in the prior step.
Procedure:
• Press
to enter Analyte Addition mode.
• Volumetrically add standard to a clean beaker. Add Stir bar and place on a magnetic stir plate. Stir
standard. 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 Sample Volume to the standard
solution. The method parameters are also displayed on the LCD.
• 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 an ISE Method Report. Press
to return to
ISE
Measure
mode.
• Press
to start another measurement. Rinse ISE sensor between samples.
• Press
, to modify the method parameters.
Note
: Press
at any time to stop the measurement and return to
ISE Measure
mode.
