Buffers
Buffer solutions serve to keep pH (acidity or alkalinity) nearly constant in a variety of chemical and biological applications. For example, a bicarbonate buffer helps maintain the pH of blood, a buffered saline maintains cellular contents at a consistent pH level, and buffers help maintain a narrow pH range for enzymes to function correctly. Dominant buffers in the human body include:
- Bicarbonate buffers
- Phosphate buffers
- Protein buffers
Most biological samples used in research are kept at a pH of about 7.4. Common biological buffers used for tissue culture include Dulbeccos phosphate buffered saline (PBS), Tris base, HEPES, MOPS, PIPES, and other formulations developed for specific cell lines or applications. Most buffers used in cell culture are also DNase-, RNase-, and protease-free.
The choice of buffer for a particular biological reaction or site depends on several factors:
- Temperature
- Desired or target pH
- Buffer toxicity (to the system)
- Buffer interactions with other system components
Industrially, buffers and buffering agents help produce the right conditions for setting textile dyes. In fermentation processes, buffers help maintain the right growth conditions for yeast and other organisms. Buffers are commonly used in chemical analyses and pH meter calibrations.
The buffers used to calibrate pH meters may be certified and/or traceable to the National Institute of Standards and Technology (NIST). These buffers may also be color-coded for easy identification:
- Red: pH 4.0
- Yellow: pH 7.0
- Blue: pH 10.0