We are anoxically synthesizing various nanophase iron oxides and need to keep a stable and narrow pH range. However, the pH electrode tends to get caked and deliver faulty readings, thus acid and base are not added appropriately. Because the syntheses are anoxic, continually removing the electrode to rinse is not an ideal option. Any suggestions are appreciated.
I suppose you use a combined pH electrode.
Use separate pH electrode and reference. For the reference use a salt bridge or a reference with a higher leaking rate (large area frit or reversed sleeve/ground joint). Stir your solution.
Dear Elizabeth,
sludge, colloid, slurry and viscous samples clog the electrode junction and coat the pH-sensing bulb, resulting in slow electrode response, measurement drift and pH measurement errors. The thickness of the sample can also cause a sample carryover problem – after the pH electrode is removed from the sample, some of the sample may cling to the electrode.
For the most accurate results and most stable measurements in these samples, use a pH electrode with a Sure-Flow or open junction and soak the pH electrode in ROSS pH electrode storage solution, Cat. No. 810001, between measurements. For the best reproducibility, immerse the pH electrode at a fixed depth in all samples. Sure-Flow junctions resist clogging, provide a constant flow of filling solution and are extremely easy to clean. Open junctions resist clogging, contain a low maintenance polymer gel as the filling solution and are easy to clean.
The ROSS Sure-Flow, Ag/AgCl Sure-Flow and AquaPro pH electrodes are recommended for measuring the pH in sludge, suspension, colloid, slurry and viscous samples. The ROSS pH electrode storage solution will enhance the pH electrode performance by acting as a very mild cleaning solution.
Options to choose from are (among others; I am NOT promoting a specific brand):
Thermo Scientific™ Orion 8172BNWP ROSS Sure-Flow pH electrode
Thermo Scientific™ Orion 8165BNWP ROSS Sure-Flow pH electrode
Thermo Scientific™ Orion Model 91-72 Sure-Flow pH electrode
Russell Quickflush pH electrode
Wishing you best of success,
Johannes
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