pH meter, what is it and how to choose the best one?

November 2, 2021

The pH meter are pH meters , scientific tools having a (electrode) sensor which operates using the electrochemical method for measuring the pH of a solution or dissolution.

The main purpose of measuring the pH or hydrogen ion activity in solutions , showing the degree of alkalinity or acidity. In this way, pH meters are responsible for measuring the difference between a pH electrode and a reference electrode, a difference that is directly related to the pH of the solution used.

Thanks to its use, the pH meter is usually used in a large number of applications within a laboratory.

What is pH?

In order to better understand how a pH meter works, it is important to be clear about and understand what pH is.

pH refers to the hydrogenic potential, which is the measure of alkalinity or acidity of a substance. That is, the concentration or level of hydrogen ions or weak acids that are measured numerically: acid solutions are indicated from 7 to 0 , while alkaline solutions are indicated from 7 to 14 . That is, the more acidic a substance will have a pH closer to 0, while the more alkaline a substance is, it will be closer to the number 14.

How does a pH meter work?

The operation of pH meters is actually quite simple, focusing on measuring the voltage between the electrodes and converting their result into the pH value that they show.

These scientific tools are composed of an electronic amplifier and electrodes , being able to use a combination electrode , and show the results on a screen that is calibrated to show the pH. Although it can vary, these kits usually have a reference electrode and a glass electrode, the combination electrode. In this case, the electrodes are introduced into the solution of which you want to know its pH so that you can measure the level and display it on the screen.

It is important to bear in mind that the design of the electrodes is very important and is a key point for the effectiveness of this equipment. They are rods that are usually made of glass that have a bulb in which they have a sensor . The glass electrode has a glass bulb to measure pH , which has been specially designed to measure the concentration of hydrogen ions.

When these are entered into the solution to be tested, the hydrogen ions that are present in the solution are exchanged for positive ions that are in the glass bulb, which generates an electrochemical potential across the bulb. When this happens, the electronic amplifier detects the potential difference between the electrodes that were generated during the measurement, converting this difference into pH units .

Calibrate a pH meter

In order to obtain an accurate pH measurement, the measure must be correctly calibrated before carrying out the pH measurement to be carried out. In fact, it is quite normal that these equipments have to be calibrated at least once a day when they are going to be used on a daily basis. The reason why this type of equipment has to be calibrated frequently is because the glass electrode does not generate electrostatic potentials when used for a long time.

Steps to perform the calibration of a pH meter

  1. You first need to remove the electrode from the storage solution, clean and dry it carefully.
  2. The pH of a buffer solution with a known pH of pH = 4 should then be measured.
  3. The equipment has to be adjusted to read the 4.
  4. The electrode is removed from the pH 4 buffer solution, the electrode is rinsed in a storage solution, cleaned and dried.
  5. The pH of a buffer solution of pH = 10 is measured.
  6. Adjust the tool to read pH 10.
  7. Remove the pH = 10 electrode, rinse, clean well, and dry.
  8. Now measure the pH of buffer 4 again. The pH meter will have to give a reading of pH = 4. Otherwise it will have to be readjusted.
  9. Go back to the pH = 10 buffer and you will have to dial a pH 10. If not, you will have to adjust again.

This standardization process is used for pH 4 and 10 buffer calibrators until an adequate and consistent reading is given. Afterwards, you will be able to use the equipment to be able to measure the pH of a solution of which the measurement is unknown.

For good laboratory practice, after a measurement has been taken, the probe should be rinsed with distilled water to get rid of any trace of the solution that has been measured. It is cleaned to remove any debris that may affect the next reading that takes place.

Different types of pH meter

Within laboratories you can find different types of pH meters, ranging from fairly simple and inexpensive equipment that almost anyone can buy to professional laboratory equipment that is more expensive and complex. The most sophisticated equipment has computer interfaces and several inputs to measure indicators or temperatures that are used when measuring the pH of a solution.

Likewise, the different equipments can have an analog or a digital output, in addition to the fact that they can also vary in terms of the use of batteries or electric current or batteries.

Special probes and meters are specially designed for more specific applications, such as being able to be used in biological microenvironments or harsh environments. Also, there are pH meters that have holographic pH sensors that allow a colorimetrically measurement using a variety of pH indicators.

You can also find pH meters that are based on solid state electrodes , differing from the glass electrodes that most of the meters that can be found on the market usually use.

Why are pH meters so important?

The truth is that the pH meter has been a fairly important scientific invention that has had a great impact. Before these scientific tools existed, the different industries and manufacturers had enough complications to be able to measure the acidity or alkalinity levels of their products.

In this way, thanks to the invention of the pH meter, the control of the acidity levels of the products became much easier . This applies across a large number of industries and products, so it actually had quite a major impact on the industry as we know it today. From companies that are dedicated to the production of soaps, beverages, etc., playing a very important role in biochemistry laboratories.

What are the parts of a pH meter?

As we have mentioned before, these are not very complex equipment, since they are quite simple devices and today they can be as small as a pencil, having a small screen that shows the pH measurement.

In this way, if we analyze the parts of which these tools are confirmed, we will find:

  • Temperature compensation element
  • pH meter (controller)
  • PH electrode

They are very simple tools, but knowing the operation of each of its parts is of great help to be able to achieve the best possible results during the measurement.

Who and when was the pH meter invented?

The inventor of the pH meter was Arnorld Oville Beckman , born on April 10, 1900 and died on May 18, 2004, a chemist and philanthropist who invented the pH meter or pH meter.

This invention came as a request from a colleague of his, Glen Joseph , who asked him for help in measuring the level of acidity in lemon juice. It was thanks to this request that Beckman decided to create a team that could accurately pinpoint the acidity level of lemon juice. I baptize his invention as a pH meter.

His invention worked quite well and he decided to create his own business manufacturing and marketing pH meters, selling them to laboratories around the world so they could make easier measurements. In this way he made a great contribution to biochemistry and all science, as well as to industry.

Dr. Loony Davis5
 | Website

Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

Leave a Reply

Your email address will not be published. Required fields are marked *