Correct Handling and Care of pH meter

Correct Handling and Care of pH meter
pH Meter
pH Meter

A pH meter can be seen in all laboratories irrespective of size – School laboratory College laboratory, University research laboratory, Commercial products testing laboratory, Industrial laboratory or even a national level laboratory.

A laboratory may not be equipped with sophisticated instruments such as AAS, GC, HPLC, LC – MS or FT – IR but it simply cannot do without a pH meter as pH measurement is a basic requirement for all chemical and biochemical reactions and process control reactions in manufacturing industries.

Even a slight variation in prescribed acidity can change the course of reactions or lead to manufacturing losses. Yet the simple pH meter is often taken for granted and its proper handling and care are overlooked.

In this article I have tried to provide some valuable tips on proper handling and care of a pH meter that will ensure correct pH reading every time you make use of it :

  1. A pH electrode is fragile and one should not be tempted to use it as a stirring glass rod when adjusting pH.
  2. A pH meter needs to be calibrated daily with the help of standard buffer solutions.
  3. pH readings are temperature-sensitive due to changes of glass electrode resistance. A 10-foldincrease in resistance results for every 30°C rise in temperature. Avoid temperature fluctuations and never keep the pH meter exposed to direct sunlight.
  4. The glass electrode should not be left out of the storage solution for prolonged intervals as the glass membrane gets dehydrated resulting in slower response and can eventually lead to complete response failure. The electrode should not be immersed in dehydrating solutions such as sulphuric acid and ethanol.
  5. Glass is rapidly attacked by hydrofluoric acid so never keep the electrode in HF solution as it can lead to irreparable damage of the electrode.
  6. Avoid vibrations and shock. When using magnetic stirrers take care to maintain adequate distance between meter bulb and the magnetic stirrer pellet to prevent accidental breakage. A heated magnetic stirrer should never be used as it can bring about a change of temperature of the solution.
  7. Handle carefully during inter-or intra laboratory transport to prevent breakage.
  8. Store sensors at ambient temperatures of 10°C to 30°C. Protective caps as well as solution storage caps provided by the supplier should be installed onto the end of the sensor when not in use. Ideally the sensor should be stored in 3 to 3.5 M KCl solution. Keep a check to ensure that the storage solution has not evaporated.
  9. Adopt the suggested cleaning procedures after use:
  • General cleaning – if the solutions are fairly clean soak in 0.1M HCL or 0.1M HNO3 for about 30 minutes
  • Bacteria or deposits – soak in 1: 10 dilution of laundry bleach for 10 min
  • Oil or grease – soak in detergent or methanol
  • Protein deposits – soak in 1% pepsin in 0.1 M HCl for 5 min.

After every soaking the electrode should be rinsed with distilled water. Droplets adhering to electrode should be gently dried with tissue paper and not rubbed or wiped.

Further reading

Useful reference and guide on fundamentals and applications of pH measurements:

What is pH, and how it is measured – A technical handbook for industry.

The above guideline will help you obtain accurate and repeatable pH readings. We welcome your views and suggestions based on your experiences.

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  1. i.m new user to atomi absorpance spectroscopy what your adviser for me ,, from start to understand the machine
    with best greeting

    1. You should first understand the basics and understand the individual components. I hope you have gone through the modules on AAS appearing in our blogs . The topics cover all the aspects raised by you and will help you get a better understanding.In case there are still any doubts please feel free to raise them.

  2. my Dr. Deepak Bhanot
    could you please to explain why the read appear uncal or over when analyse sodium element by flame , mention method we use st 1.5-1-.5ppm and concentration sample in d.w 1g/100ml

    1. Dear Sabri,
      In the topic I have covered handling and care of pH meter but from your comment it appears that you have mixed it up with elemental analysis.I am not clear on the query raise by you.

  3. Dear Bhanot,
    Very informative article covering the basics and complexities involved in the simple pH measurement.

    1. Thanks Dr Ramachandra.we are glad to note that the information provided was interesting and useful.Your feedback serves to motivate us.

  4. Dear Deepak Sir,

    Very nice and useful article from U.
    Thanks a lot.

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  8. why do I get a lower ph reading when the stirrer is at rest and a higher one when it’s running?


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