Nearly every experiment in the field of biology will involve examining the actions of enzymes and other proteins. When these proteins are involved in your experiment, you will need to keep your experiment’s environmental pH level stable due to pH modifications that occur during the course of the procedure. Using the right buffer liquid is crucial to maintaining the pH of the environment and executing a successful experiment overall. However, it can be difficult to select the right buffer for your specific needs.

What Is a Buffer?

A buffer is a liquid that scientists use to resist changes in hydrogen ion concentration during experiments with enzymes and active proteins. These fluctuations can affect the pH system of the experiment’s environment, which can affect the experiment’s overall outcome. Researchers use buffers in many types of experiments and molecular screening.

A buffer contains a weak acid and its conjugate base. It can also contain a weak base and its conjugate acid. Since weak acids and bases do not completely dissociate in water, they can exist within the experiment’s environment in equilibrium. All buffers contain an optimal pH so that they can absorb and moderate the changes in hydrogen ion concentration that may take place, allowing your experiment’s pH to remain stable throughout the procedure.

What Are the Different Types of Buffers?

You can choose between two types of buffers: acidic buffer solutions, which contain a weak acid and its conjugate base, or alkaline buffer solutions, which contain a weak base and its conjugate acid. Acidic buffer solutions have a pH below 7 and usually contain an associated salt as a conjugate base. Alkaline buffer solutions have a pH above 7 and have an associated salt as a conjugate acid.

Scientists choose a buffer based on the pH level of the experiment itself and the buffer’s pH range. When you use a buffer in your experiment, you should keep the same buffer throughout the entire study to maintain consistency. Buffers are only effective at pKa values within 1 unit of your experiment’s pH value. For example, if you have a pH value of 7.1, you should choose a buffer with a pKa between 6.1 and 8.1. If you believe your experiment could lower the pH of the environment, choose a buffer with a lower pKa level. If you believe your experiment would increase the pH of the environment, choose a buffer with a higher pKa level.

What Makes a Good Buffer?

There are certain characteristics you should look for when choosing your laboratory buffer. Different buffers work better with different types of experiments and conditions. Depending on your laboratory needs, choose a buffer according to these characteristics:

• Solubility: When you choose a buffer for your experiment, you should choose one that is highly soluble in water. The buffer should not be as soluble in other nonpolar solvents, such as oils, fats, and other organic solvents. By choosing a buffer in this ideal solubility, you prevent the buffer from accumulating other organic, nonpolar substances during the course of your experiment.

• Stability: You should choose a buffer that is chemically stable. This quality will help your experiment resist changes such as enzymatic degradation.

• Ionic strength: You want to make sure that whatever buffer solution you choose does not have an impact on your experiment’s ionic concentration.

• Membrane impermeability: You do not want your buffer to pass through cell membranes. Choose a buffer that does not permeate membranes. This will help you reduce an improper accumulation of your buffer in other structures in your experiment.