Electrode Preparation for Water Sample Determination of Portable Dissolved Oxygen Meter
1. Electrode preparation for water sample determination of portable dissolved oxygen meter
All newly purchased dissolved oxygen probes are dry, and must be filled with electrode filling solution before use, and then connected to the instrument. The connection steps are as follows:
①Assemble the electrode according to the instrument manual.
② Add electrode filling solution to the electrode.
③ Gently spin the film onto the electrode.
④ Tap the edge of the electrode with your fingertips to ensure that there are no air bubbles in the electrode. To avoid damage to the film, do not tap the bottom of the film directly.
⑤ Make sure the rubber O-ring is correctly positioned in the diaphragm cover.
⑥ With the sensor facing down, turn the membrane cover clockwise, and some electrolyte will overflow. When not in use, put on the supplied film protective cover.
2. Portable dissolved oxygen meter water sample determination electrode polarization calibration process
The electrodes were polarized at a strength at a fixed voltage of approximately 800 mV. Electrode polarization is important to the reproducibility of the measurement results. With the electrodes properly polarized, the oxygen passing through the sensor membrane will dissolve in the electrolyte in the electrodes and be continuously consumed. If the polarization process is interrupted, the oxygen in the electrolyte will continue to increase until it reaches equilibrium with the dissolved oxygen in the external solution, if an unpolarized electrode is used, the measured value will be the sum of the dissolved oxygen in the external solution and the solute in the electrolyte , this result is wrong. When polarizing the electrode, cover the white plastic protective cap (remove during calibration and measurement).
① Press ON/OFF to turn on the instrument.
②The letter "COND" appears on the display, indicating that the electrode is automatically adjusted (polarized).
③ Wait for 20 minutes to ensure that the electrodes are stable.
④ The instrument will automatically polarize itself to an accurate saturation value. After about 1 minute, the display will display "100%" and small characters "SAMPLE", indicating that the polarization calibration has been completed. NOTE: Be sure to redo the polarization calibration whenever the electrode, membrane, or electrolyte is changed.
⑤If you want to exit the calibration mode during the calibration process, just press the CAL key again.
⑥Press the RANGE key to switch the instrument from saturation percentage (%) to mg/L state (no need to recalibrate).
