emäsparista

Emäspar, known in English as a buffer solution, is a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. Its primary function is to resist changes in pH when small amounts of an acid or a base are added. The term “emäsparista” refers to information about these buffer systems, including their chemical composition, operating principles, and applications.

Buffer capacity, a key descriptor of a buffer, quantifies the amount of acid or base that can be added before a noticeable pH change occurs. It depends on the concentrations of the acid and base components, the dissociation constants (Ka) of the weak acid, and the temperature. For a buffer of a weak acid HA and its salt A−, the Henderson–Hasselbalch equation pH = pKa + log([A−]/[HA]) provides a simple estimate of the pH, assuming the contributions of water autoionization are negligible.

The most widely used buffer systems in biology are based on phosphate (pKa≈7.2) and bicarbonate (pKa≈6.1), which maintain the intracellular and blood pH, respectively. In industrial settings, buffers such as acetone–acetic acid (pKa≈4.7) are used in crystallization and chromatography. Softwares and laboratory kits now enable the design of custom buffers for specific pH ranges and buffering capacities.

Historically, buffer solutions emerged in the 19th century when chemists sought to control pH for reproducible analytical results. The development of titration techniques and the standardization of pH meters further refined buffer design. Today, buffers are indispensable in analytical chemistry, biochemistry, environmental monitoring, and pharmaceutical formulation, ensuring stability in reaction environments and in biological systems.