pH Electrodes
pH measurements are required in a multitude of applications and, accordingly, have different requirements. In this situation choosing the right electrode becomes an important factor affecting measurement’s accuracy and sensors’ durability. To improve your results Carl Stuart has to offer a full range of more then 30 pH electrodes from well know manufacturer WTW. With our Applications for SenTix® PLUS Electrodes table you are just one click away from choosing the right sensor! Additionaly we have prepared a list of good laboratory practices that will help in everyday’s work.
Storage
Store pH and redox electrodes in the solution for filling the reference electrodes (immerse up to diaphragm). In most cases this is a 3 mol/l KCl solution . Low maintenance electrodes should also be stored in a KCl solution after cleaning and rinsing with distilled water.
Measuring
Open the refill opening on refillable pH and redox electrodes before performing measurements. Immerse the sensor into the medium to be measured at least up to the diaphragm. When using refillable sensors pay attention to the electrolyte fill level (see refilling). Rinse the sensor with distilled water between measurements, however do not wipe off. Carefully dab off excess drops.
Calibration
For quality relevant pH measurements it is necessary to calibrate and, if necessary, adjust the pH measuring equipment using buffer solutions to ensure that they meet the requirements for measuring accuracy. If buffer solutions are taken from a bottle, ensure that the bottle is reclosed immediately after removal. Never return the used buffer solution to the bottle, always throw it away. DIN buffer solutions in ampoules are recommended for higher quality requirements, because such ampoules always contain fresh, single portions of the solution. Redox sensors are not calibrated. They can be checked for proper function using appropriate test solutions.
Refilling
Refillable pH and redox sensors should be filled with electrolyte solution so that the fill level of the electrolyte solution is at least 5 cm above the level of the medium to be measured. SenTix electrodes can be refilled simply by pumping electrolyte solution into them with a small dispensing bottle.
Cleaning
In most cases rinsing electrode after measurement with clean water is just enough. But sometimes, depending on the degree and type of contamination an additional steps may be required. Submerge only the glass membrane or the glass membrane and diaphragm in the cleaning solution. Ensure that any cleaning agent, which has leaked into the electrode, does not come into contact with the reference system; if necessary rinse out the reference electrode with electrolyte solution. We recommend the methods listed below depending on the degree of contamination. After cleaning rinse off the sensor with distilled water and condition it for one hour or longer in electrolyte solution. Recalibrate the measuring equipment before performing further tests.
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