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Thermo Scientific Orion Star LogR™ Meter User Guide
Advanced Orion Star LogR Meter’s Electrode Diagnostics
Initial electrode check
To get the most out of the Orion Star LogR meter’s diagnostics, you may want to
establish a regular schedule of resistance testing. Perform an initial check of your
electrode resistance and record the temperature and resistance value in the table
below, or perform a LogR calibration and output the calibration information from
the meter to a computer or printer. (Refer to the chapter titled LogR and Automatic
Temperature Compensation (ATC) Calibration and the chapter titled Data Archiving
and Retrieval for more information).
1. Rinse the electrode with deionized water and blot dry with a lint-free tissue.
2. Insert the electrode into the solution and gently stir - if a stirrer probe is enabled,
press the stir key to start and stop stirring.
3. Record the temperature and resistance value for reference.
Note:
Electrode bulb thickness and diameter vary from electrode to electrode
resulting in normal variation in resistance. In most cases the initial value is not a
definitive test of electrode condition except in extreme cases, for example, see the
initial low readings
information below. When changing electrodes, do not be alarmed
if the resistance varies dramatically from your previous electrode.
Initial low readings –
If the resistance is below 1 MΩ in a solution at room
temperature (22 ° to 27 °C), this indicates a damaged electrode. In this case the
electrode will most likely need to be replaced.
Periodic electrode testing
Periodically check your electrode resistance following the steps above and record
values in the table below. While diagnostic testing at (or near) 25 °C is ideal due to
the resistance stability at this temperature, this may not be possible. Nonetheless,
it is important to maintain as many sampling variables constant to get the most out
of your periodic testing. The resistance reading is fully dependent on temperature.
When testing, using the same solution type at a known, stable temperature at
or around the same temperature value each time would be the most beneficial
method.
Small variances in resistance –
Resistance will typically increase as the bulb ages.
This is no cause for concern. Over time this can lead to slower response rates,
