Double Known Addition - Thermo Scientific Orion Versa Star Pro User Manual

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Chapter 4 pH, pH/ISE and pH/LogR Measurement Modules
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64 Orion Versa Star Pro Meter User Manual

Double Known Addition

The sample volume should be 100 mL.
The concentration of the standard should be 100 times the expected sample concentration.
The volume of the first addition should be 1 mL and the volume of the second addition should be 10 mL.
1. Prepare the ion selective electrode (ISE) according to the instructions in the electrode user
manual. Prepare all required solutions (ionic strength adjusters, standards, etc) and review
any special requirements outlined in the electrode user manual. Connect the ISE, and any
other electrodes to be used, to the module inputs on the selected channel.
2. In the measurement mode, press the channel key until the channel with the pH/ISE
module with ISE connected is shown. If needed, press the mode key until ISE
Measurement is shown as the measure mode and use the
Electrode Type.
3. In the measurement mode, press the setup key.
4. Press the ,,  or  key to highlight Channel 1, Channel 2, Channel 3 or Channel 4
and press the f3 (Select) key.
a. Select the appropriate channel number that the ISE is connected.
5. Press the  or  key to highlight Incremental Techniques and press the f3 (Select) key.
6. Press the  or  key to highlight Double Known Addition and press the f3 (Select) key.
7. Enter the sample volume using the numeric keypad and press the f2 (Accept) key.
8. Enter the total volume (sample volume plus added ISA volume) using the numeric keypad
and press the f2 (Accept) key.
9. Enter the standard concentration using the numeric keypad and press the f2 (Accept) key.
10. Rinse the ISE and any other electrodes in use with distilled water or rinse solution required
for that electrode. Blot the electrode dry with a lint-free tissue or shake the electrode, place
into the prepared sample and press the f2 (Next) key.
a. Follow all electrode rinsing and drying instructions or exceptions in the ISE user
manual. Do not wipe or rub the sensing element of the electrode.
11. Wait for the mV value on the meter to stabilize and press the f2 (Accept) key.
12. Enter the first standard volume using the numeric keypad and press the f2 (Accept) key.
13. Add the first specified volume of the standard to the sample and press the f2 (Yes) key.
14. Wait for the mV value on the meter to stabilize and press the f2 (Accept) key.
15. Enter the second standard volume using the numeric keypad and press the f2 (Accept)
key.
Double Known Addition Recommendations
ISE Mode Menu to set the
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