If you remember those science experiments from school where you used litmus paper to test solutions, you probably know what pH is. In essence, it’s a common scale used to measure the acidity and basicity of a solution containing water as a solvent (aqueous). Without the presence of water, you cannot measure the pH of a substance. While the litmus paper experiment in school is cool, in a real-world setting, scientists use pH meters to measure the pH of a solution. Below, we explain what a pH meter is and how to use it.
“What do you use to measure pH?” Most people will learn how to use a pH meter that’s one of the three types below:
- Benchtop – Laboratories mostly use this type of pH meter to test samples/solutions that are brought on-site. These meters are heavier and have more customizations that allow for more precise results.
- Portable/handheld – This type of pH meter is typically used in the field, and is light and small in size.
- Pen – these are perfect for testing pH within test tubes and smaller containers. Pen pH meters are extremely portable and usually inexpensive, though they may not be as durable or accurate as benchtop or handheld pH meters.
Components of a pH Meter
Portable pH meters have two parts: the meter component, which displays readings and other info (and contains controls), and an electrode to dip into the solution which pH needs to be measured. Benchtop pH meters often additionally have an arm that holds the electrode and can be moved up and down into beakers and other lab containers. When pH meters are automated, this arm is often a robotic arm.
What do we need to consider when selecting the right type of pH meter for our laboratory’s requirements?
Choosing the appropriate pH meter type is crucial for ensuring optimal performance in our laboratory. We have several options available, including benchtop, portable/handheld, and pen pH meters, each serving different purposes. Benchtop pH meters offer greater customization and precision, making them ideal for lab-based applications.
On the other hand, portable/handheld models are lightweight and suitable for fieldwork, while pen pH meters provide portability at a lower cost. Understanding our specific needs, such as intended use, environment, and budget, will guide us in selecting the most suitable pH meter type for our laboratory.
Step 1: Calibration
Those learning how use pH meters are often told that they first need to calibrate the meter. So, why is it necessary to calibrate a pH meter before you use it? That’s because with use, the electrode of a pH meter tends to erode over time, and this causes the reading to become inaccurate. The calibration process is important to ensure that your pH meter is capturing the pH of a solution precisely despite some changes to the electrode.
Calibration is done by placing the electrode into at least two standard buffer solutions with a known pH. Usually, one buffer solution would have a pH of 4.0, and the other solution would either be a pH 7.0 or 10.0. Once the electrode is placed into either of these solutions in calibration mode, the user would have the option to set the meter to the correct pH as per the buffer solution. This helps the meter show the correct reading even with incorrect or compromised data — due to electrode function decline.
What are the essential steps for calibrating, and why is calibration critical for accurate measurements?
Calibration is a fundamental aspect of pH meter usage to ensure accurate and reliable measurements. Over time, the electrode of pH meters may erode, leading to inaccurate readings. Therefore, it’s essential to calibrate the device regularly to compensate for electrode degradation. The calibration process involves immersing the electrode in standard buffer solutions with known pH values, typically pH 4.0 and pH 7.0 or 10.0.
By calibrating the pH meter based on these buffer solutions, we can ensure that it accurately measures the pH of our sample despite electrode variations. Implementing effective calibration protocols helps maintain measurement accuracy and data integrity in our laboratory.
Step 2: Operation Steps
Once the meter has been successfully calibrated, it will be ready to use for testing. First, the electrode should be washed with deionized water to cleanse it thoroughly and dried with scientific wipes to avoid dilution of the sample being tested. After this, place the electrode in the solution and take its reading. After use, pH meters should ideally be kept in a suitable storage solution. These are the necessary steps to ensure the most precise readings.
How can we optimize operation and leverage automation to enhance efficiency and accuracy?
Maximizing the efficiency, accuracy, and longevity of pH meters requires proper operation and maintenance practices. After calibration, it’s essential to cleanse the electrode with deionized water and scientific wipes to avoid sample contamination and ensure precise readings. Additionally, storing the pH meter in a suitable storage solution helps preserve its performance between uses. Furthermore, integrating pH meter automation into our laboratory workflows can streamline testing processes and minimize errors. Automation solutions, such as robotic systems and data management software, enhance workflow efficiency and data traceability, ultimately improving overall laboratory productivity and quality of pH measurements.
Laboratories that would like to take it a step further should invest in pH meter automation, integrated with other systems that complete a process. Need more info? Contact Hudson Robotics, and we can help.
