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Image of liquid and ph scale for article on devices that measure pH
Published On: December 14th, 2021

Studying Microbe Colonies

Are you curious about what pH probes measure, why pH is important, and how  devices that measure pH work? In high school chemistry, you might have used pH litmus paper strips to test liquids, but pH measurement probes can be far more accurate than paper test strips.

Litmus paper was discovered in the 14th century, and it is made by treating paper with dye from lichens. The dye reacts to the acidity or basicity of the solution, staining the paper. Since then, our ways of measuring pH have advanced greatly. Keep reading to learn more about laboratory pH meters.

What Does a pH Probe Measure?

A pH probe measures the acidity or basicity of a liquid solution. The acronym pH stands for “power of hydrogen” and it is mathematically expressed as the inverse log of hydrogen ion concentration. Acidic substances release hydrogen ions, and basic substances absorb hydrogen ions.

The pH scale ranges from 0-14, with water as the neutral midpoint at pH 7. Lower pH substances under pH 7 are acidic, and higher pH substances above pH 7 are basic. The pH scale is logarithmic, meaning that each increasing step on the scale represents a hydrogen concentration number that is 10x greater than the previous scale value. With such a large range on the pH scale, the advantages of lab-quality devices that measure pH include the ability to make accurate measurements.

You are probably familiar with some household acids and bases, because these are often used as cleaning solvents. Lemon juice is an acid with a pH of 3, and baking soda is a base with a pH of 9. Coffee and tomatoes are acidic with a pH of 5, but less acidic than lemon juice.

Why are pH Measurements Helpful?

Scientists use pH probes to measure the characteristics of a liquid. This can help identify unknown liquids. pH is also critical when assessing water quality. Finally, pH measurements help scientists control variables in lab experiments. Microbiologists know that some microbes thrive in acidic environments, while other microbes die when exposed to acid.

Ensuring that the pH of solutions used in the lab is in an acceptable range is key to experiment success. Preserving sensitive microbes by choosing the right pH for media is another of the advantages of lab-quality devices that measure pH. Other uses include formulations of new drug entities – pH is one of a number of basic characteristics that are measured to create formulations that best preserve drug entities.

How Does a pH Probe Work?

One of the advantages of lab-quality devices that measure pH is that pH probes provide quantitative readings, unlike qualitative litmus paper tests. A pH probe works by using electrodes to measure the charge of hydrogen ions. A glass electrode and a reference electrode form a circuit. As the liquid moves toward the glass electrode, it exchanges ions with the electrode. The metal electrode releases ions into the liquid.

The ion swapping creates an electrical charge, which is measured by the probe. A pH probe is a form of voltmeter. The bigger the voltage, the higher the acidity of the solution.

Improve Your Lab’s pH Measurements

The advantages of lab-quality devices that measure pH include reducing reading errors, increasing lab throughput, and improving the accuracy of pH measurements.

Hudson Robotics offers a range of laboratory pH meters that can provide these benefits for your lab.

Some of the pH meters can be automated, further increasing efficiency. Others are suitable for use with viscous fluids, which can reduce the need to dilute. Learn more today about devices that measure pH!