Some measurements—like weight and temperature—seem intrinsic to lab work. Another such measurement is pH. On a scale of 0 to 14, pH serves as a universal language to quantify how acidic or alkaline a solution is, helping provide valuable insights into various processes. For biological research, pH can determine if a biological system will function as expected, DNA will lyse, a protein will keep or lose its structure, or if a finished product will maintain viability in the package.
Because pH measurements are so common in the lab, it can be easy to forget their importance. However, these measurements are critical to avoiding delays in research or damaging samples, especially in areas like cell and gene therapy research, where cell samples can be limited.
The undeniable importance of pH
Biological processes can be very sensitive to pH, so maintaining optimal pH for a specific application is vital to keeping cells healthy so they can grow faster, live longer, and show less stress. Cells can even die if factors like pH aren’t within the required range. Additionally, due to pH-induced changes in the polymer and the resulting polyplex, the pH of cationic polymer transfection solutions can affect gene expression, while the culture medium pH can influence how efficiently transfection happens. pH also affects protein solubility, structure, and stability. For research on recombinant proteins, each step of recombinant protein production has pH-dependent variables that can influence yield and performance, and proteins may fold improperly if the pH isn’t correct. Another example where pH is critical is in monitoring gene expression, where primary cells must be cultivated at the proper pH. As research into molecular biology, cell and gene therapy, and mRNA vaccines continues to expand, it will be even more critical that labs pay attention to getting pH right.
How pH can go wrong
Ideally, pH calibrations are easy and successful, while pH readings are quick, accurate, and reliable. However, several common challenges can arise for labs regarding pH, all of which can lead to delays in timelines and additional work. For example:
- pH calibration may fail and must be repeated, or the pH meter may not seem to calibrate
- pH readings can be slow and take too long to stabilize
- Adjusting the pH of the solution can take too much time, and it can be hard to get the correct pH
- pH results may not come out as expected or seem unreliable
Any of these problems can slow down work and run the risk of damaging vital samples.
A pH measurement system includes the pH meter and the pH electrode, which senses the sample pH. The pH electrode is vital to accurate and repeatable measurements, but not all pH electrodes are made the same. Some labs can run into issues where pH electrodes last only a short time and must be replaced more frequently than desired. Labs can also have concerns that the pH electrode may not be compatible with their samples and might contaminate them. Finally, standard pH electrodes can sometimes be too large for small samples in microcentrifuge tubes or narrow cell culture tubes. Each lab may have specific requirements for pH electrodes, so labs must ensure they’re selecting the right electrode for their sample types, sample sizes, and desired processes.
What labs can do to get pH right
Biological buffers and pH calibration buffers are important parts of getting pH right. The biological buffers used for research and bioproduction help maintain the desired pH to ensure cell systems are optimized, proteins are extracted and separated correctly, and chemical reactions proceed as planned. pH calibration buffers are critical for valid pH measurements.
To ensure accuracy and reliability, labs should select pH calibration buffers that are traceable to standard reference material providers, such as the National Institute of Science and Technology (NIST). Ensure the pH calibration buffers are within their expiration date and use fresh buffers each day a calibration is done. Discard used pH calibration buffers after one day. Do not calibrate with old, used buffers.
A good pH measurement system and the proper handling and care of pH electrodes will simplify work and increase confidence in results. Labs should select bench meters with a user-friendly interface, on-screen instructions, and auto-calibration features for quick and reliable pH calibrations and measurements. pH measurement and calibration data logging support dependable record keeping and data traceability. pH electrode choice is also critical when dealing with solutions and samples in the cell culture laboratory. Selecting a pH electrode with a double-junction design helps prevent sample contamination and electrode malfunction, making the electrodes compatible with several applications.
Incorporating pH best practices into your lab
pH is critical for labs to get right the first time. Given the importance of pH in cell culture, pH measurements must be done quickly and accurately, and labs should calibrate pH daily to avoid unnecessary delays or the need to redo work. pH testing can be simple and straightforward when working with the proper pH measurement system and practicing good pH electrode handling and care.
