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Image of pH measuring robot for article on automated pH testing.
Published On: September 7th, 2021

An automated pH meter is a device that measures a sample from each of the wells in a microplate plate and measures the pH. Most commonly used are 96 well microplates, although other microplates such as 48 and 24 well plates are used. Throughout the entire process, there is no technician involvement, and when the process is finished, the pH is displayed and captured in a data file for each of the 96 wells.

During the 96 measurements, the technician is free to perform other tasks. Using an automated pH meter for viscous liquids is just as easy. To begin, let’s review pH meters in general.

What Is a pH Meter Used For?

A pH meter is a device for measuring free hydrogen ions (H+) in a solution. Modern pH meters are electrical and measure the amount of free hydrogen ions present in a liquid using two electrodes that act like a battery in the solution.

The pH meter measures the amount of electrical potential between the sample and reference electrodes. This difference determines the amount of hydrogen ion present and is converted from 0 (maximum acidity) to 14 (maximum alkalinity). Although a bit more complicated, a pH meter for viscous liquids works essentially the same way. To ensure accuracy, pH probes and meters are calibrated using pH standards that bracket the expected pH range of the samples.

What Does a pH Probe Measure

Modern pH meters, even a pH meter for viscous liquids, have a single probe. Inside the probe are two electrodes: one is the “reference electrode” while the second is the “internal electrode”. The electrical potential between the two electrodes is what generates the signal that the pH meter can compare to a standard curve and calculate the pH of the test solution.

How to Use a pH Meter

When using a standard or a pH meter for viscous liquids, the first step in using a pH meter is to clean it with deionized water and carefully dry it properly.

This is necessary to ensure there is no residual solution from a previous sample on any part of the pH probe. Next, the probe and meter must be calibrated by following the probe manufacturer’s procedure, using a high and low calibration standard. Between solutions, the probe must be rinsed and dried. Once calibration is complete, the probe must again be rinsed and dried before it can be placed into the sample solution, where the pH will be read and recorded.

After the sample reading is taken, the probe must be rinsed for the final time, dried, and properly stored in the appropriate buffer solution, usually of a neutral pH of 7.0. So, to perform a single manual pH reading will require anywhere from 2 to 4 rinses with deionized water followed by drying. Using a pH meter for viscous liquids is even more difficult and time-consuming with a manual pH meter.

pH Meter Automation

There is a much easier way to perform pH readings. An automated pH meter not only performs each step automatically with no human intervention, but it can measure the pH of every sample in a 96 well (or fewer) plate. And it can measure the pH of all 96 wells much faster and more accurately than even the best-trained technician. A pH meter for viscous liquids measures even faster than standard meters.

With automation, the top benefits include:

  1. Minimization or elimination of errors (especially operator error).
  2. Time is saved as every step of pH measuring is automatic, freeing technicians and scientists to perform other tasks.
  3. Due to smaller reagent needs, fewer mistakes, and higher reliability, accuracy, and experimental reproducibility, operating expenses decrease.
  4. They are simple to use and easy for anyone to learn.
  5. With automation, laboratory safety increases with no human exposure to dangerous reagents or samples (e.g., highly acidic or alkaline).

pH Meter for Viscous Liquids

Viscous liquids add a host of challenges when measuring pH. Viscous liquids include paint, cosmetics, and certain foods.

The pH reading fluctuates with a standard pH meter, never stabilizing at a single reading.

The problem is that the standard pH meter has electrodes that require a continuous flow of the liquid. A viscous sample, however, does not flow well, causing pH values to fluctuate. The answer is a pH meter for viscous liquids, which uses a special electrode that measures pH in liquids that have little flow. Automated pH meters come in a variety of designs depending on a laboratory’s needs. It is even possible to have an automated pH meter for viscous liquids.

Hudson Robotics is the leader in life science and pharmaceutical laboratory automation. With almost 40 years of experience, they are your best resource for information about automated pH meters, including pH meters for viscous liquids. They specialize in all aspects of laboratory automation.

To ensure you maintain your competitive edge, contact Hudson Robotics today.