How To Select pH Electrodes   pH electrodes. Gel filled electrodes. Pharmaceutical pH electrode Image Credit: Test Equipment Depot | Omega Engineering pH electrodes are analytical sensors for measuring potential of hydrogen (pH), the negative logarithm of the hydrogen ion activity in solution. The pH value of a substance is directly related to the ratio of the hydrogen ion [H+] and the hydroxyl ion [OH-] concentrations. This is one of the most common laboratory measurements...
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Q & A on pH Electrodes

We asked our users for their input on pH Electrodes. Here are the results of 149 users familiar with pH Electrodes.

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice |

Who Took Our Poll?Top

Design TrendsTop

Q:
What new technologies are influencing pH electrode design?
21 answers
Answers:
Lifespan is normally less depending on the fluctuations of the pH level of water. Good designs and good engineering should help in creating a much better product.
~Rodgers Nalianya, Engineering Consultant, Nairobi, Kenya
Membrane types and materials, new ISFET electrodes, combined electrodes with special forms (for example, in-vivo electrodes).
~Kovacs S., Director, Debrecen, HUNGARY
Classical kcl fillable type electrode works. Filled electrodes have to be discarded because of tough conditions.
~RAJIVA K, Process Engineer, THANE, INDIA
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Q:
From your perspective, which companies are creating the most innovative pH electrodes?
22 answers
Answers:
Difficult to say; I am using Ahlborn product for lab type measurements and series of different portable units, considered as throw away devices, for on site sampling. I do not have enough long experience to qualify the main specification for me, which is expected life.
~Jean-Claude K, Quality Control, Paris, France
ISFET pH - IQ Scientific now HACH LANGE SENSOREX, WTW, HANNA, METHROM - industrial and laboratory, In vitro medical (blood) - ESCHWEILER, RADIOMETER ISE for laboratory - NICO 2000
~Kovacs S., Director, Debrecen, HUNGARY
Thermo Scientific, Mettler, Schott Analytics (ITT) Fisher Accumet, Denver Instruments, Hach
~Bob, Marketing Manager, Kenner, LA
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Applications and UseTop

Q:
What are some of the applications you have used pH electrodes for?
39 answers
Answers:
I have used pH electrodes in a reactor where a sodium salt of organometallic compound is made in aqueous medium. reaction products include sodium sulfite carbon di sulfide etc. We have the electrode in a circulating loop which is activated when neutralization with alkali is on. We have to control pH 8.8 to 9.0 to get optimum stability and yield of the product.
~RAJIVA K, Process Engineer, THANE, INDIA
Measurement and adjustment of standards and reagents. Working with customers in drinking water, waster water, food & beverage, research, pharma, environmental, pulp and paper etc.
~Bob, Marketing Manager, Kenner, LA
Scrubbers, Incineration, Dyes and Pigments Manufacturing, Raw Water / Waste water treatment, White liquor, High Purity Water pH monitoring etc..
~PRASHANT T, DIRECTOR, MUMBAI, INDIA
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Q:
Please share with us any “non-standard” applications that pH electrodes have been used for.
10 answers
Answers:
Flat surface electrodes for skin, fruits etc. ISFET pH electrodes in steel house for meet or 2 mm in diameter and 20 cm long scientific electrodes ISFET pH for small volume (one drop). In vivo gastro pH electrodes. In vitro medical (blood) - capillary electrodes for 100 µl of blood measuring High pressure and temperature, self cleaning special pH constructions.
~Kovacs S., Director, Debrecen, HUNGARY
I am currently working to couple an USB data logger with a pH electrode for long term (3 months) monitoring of an ecosystem. Today it is working well with temperature, should be quite simple for conductivity, needs more investigations for pH.
~Jean-Claude K, Quality Control, Paris, France
This is a very nonstandard application as we have tried many manufacturers with little success.
~RAJIVA K, Process Engineer, THANE, INDIA
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Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of pH electrodes?
12 answers
Answers:
No disasters but probe failures and production downtime. Once some customer had used a pH glass electrode in a food processing application which we told to avoid/remove fearing breakage could result in catastrophic results to the consumer.
~PRASHANT T, DIRECTOR, MUMBAI, INDIA
We have had over dosing of sodium hydroxide caused by a pH monitor changing its range following calibration... bit of a near miss!
~Trevor D, Instrument Tech, Bristol, UK
Using distilled water for calibration at pH=7,00. Working in solid acids and basical solution with simple pH-electrodes.
~Kovacs S., Director, Debrecen, HUNGARY
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FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
22 answers
Answers:
- High temperature probes for above 150 deg C - Some material where solvents do not create a problem.. - Probes which can operate well in HF applications and not restrict themselves to 3-8 pH range. - Self cleaning probes (ultrasonics please excuse) - Sounds silly but non contact pH monitoring through change of color of any pH sensitive material inside the vessel duly detected by a color sensitive detector
~PRASHANT T, DIRECTOR, MUMBAI, INDIA
Robustness (stability, autocleaning or auto calibration features); data logging capability (such as 32000 measurements with 1/hour and 1 year battery); USB interface; small size unit even without display like USB temperature data loggers.
~Jean-Claude K, Quality Control, Paris, France
Integrated fill hole in cap or body, electrode storage sleeve to protect body and condition bulb, reference junction that can easily be cleaned.
~Bob, Marketing Manager, Kenner, LA
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Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using pH electrodes?
13 answers
Answers:
- Purchase a quality product. You will pay more but it will be worth it. - Understand your application and what you need for an electrode (Do you need single junction or double junction, free flowing junction, viscous sample) - Understand temperature range (Electrodes are made for different temperature ranges and respond differently to temperature extremes) - How skilled are you users and how will they maintain the electrode (lean towards buying a gel filled electrode or refillable)
~Bob, Marketing Manager, Kenner, LA
Check if the device needs calibration before use (when measuring multiple water parameters this makes the use cumbersome). An accuracy of 0,1 pH is enough for ecosystems evaluation. Think that the expected life of such device is short so look at instruments with replaceable sensors or select cheap devices and consider them as throw away instruments.
~Jean-Claude K, Quality Control, Paris, France
PH probes are like babies, you have to do the right kind of maintenance and take operational care of the same. Do not expect a fit and forget type of pH probe (mostly).
~PRASHANT T, DIRECTOR, MUMBAI, INDIA
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Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of pH electrodes?
10 answers
Answers:
In selection - please know your process! Like pH fluctuations over the range, pressure, temperature and coating probabilities on the material. In usage - Do not let it go dry, avoid pH shock & temperature shock, ground the equipment well and avoid ground loops. LAB readings of the probe are never going to match with the ONLINE Process probes. BE AWARE.
~PRASHANT T, DIRECTOR, MUMBAI, INDIA
- Clean your junction at least weekly by thoroughly rinsing - Change filling solution weekly if refillable - Use electrode cleaners regularly if measuring in tough samples - Storage in pH storage solution of pH 4 or 7 buffer to keep bulb conditioned
~Bob, Marketing Manager, Kenner, LA
If the sensor is fixed on a line with pressure make sure that it is tight enough and users are well educated in using it.
~Rodgers Nalianya, Engineering Consultant, Nairobi, Kenya
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