A chemical solution that counteracts small changes in pH when acids or alkalis are added to it. Buffers play an important role in cells and tissues, which usually function best at or near neutrality (pH 7) since changes in pH adversely affect metabolic processes. Examples of buffers in cells are phosphates, borates, and bicarbonates (hydrogen carbonates).
Buffers are used in microscopy to reduce the production of artefacts by maintaining the specimen at its original pH during fixation. Sorenson's phosphate buffer and sodium cacodylate are two of the commonest buffers for electron microscope preparations of plant material.