58
59
Procedure:
• Press
to enter Known Addition mode.
• Volumetrically add sample to a clean beaker. Add Stir bar and place on a magnetic 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.
• If following an established procedure: Press
then edit the method variables and follow the
procedure below.
• 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 Known Subtraction analysis it is important to determine
what sample volume, standard reactant concentration and standard volume will produce the best results
and the way the Reagent will react with the measured Ion on a molar basis (Stoichiometric factor). As
a general rule, the addition of standard should change the mV value of the sample by 15-20 mV.
For a positively charged Ion (i.e. Calcium), the reactant addition should decrease the mV. For a
negatively charged Ion (i.e. Sulfide, Fluoride, Chloride), the reactant addition should increase the mV.
Start with a small trial. For example: Measure 50 mL of sample, add a magnetic stir bar, 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 Reactant standard. 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 reagent addition.
• Press
then edit the procedure variables to the volumes determined in the prior step.
Procedure:
• Press
to enter Known Subtraction mode.
• Volumetrically add sample to a clean beaker. Add stir bar and place on a magnetic 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 Reagent 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 an ISE Method Report. Press
to return to
ISE
Measure
mode. Press
to start another measurement. Rinse ISE sensor between samples.
• Press
, to modify parameters.
Note
: Press
at any time to stop the measurement and return to
ISE Measure
mode.
ANALYTE ADDITION
To measure the concentration of a sample using Analyte Addition method:
• Press
and then
to select
ISE Measure
mode.
• Select the Analyte Addition method (see ISE Setup > Reading mode).
• Prior to starting an AA 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 AA.
• If following an established procedure: Press
then edit the method variables and follow the
procedure below.
w
w
w
.
.c
om
in
fo
rm
at
io
n@
itm
.c
om
1.
80
0.
56
1.
81
87
