Buffer solutions

Maintenance of PH in blood and in intracellular fluids is absolutely crucial to the processes that occur in living organisms. This is primarily because the functioning of enzymes is sharply pH dependent. The normal pH value of blood plasma is 7.4 and several illness or death can result from sustained variations of a few tenths of pH unit. Also many medical and cosmetic formulations require that these must be kept and administered at a particular pH. There are solutions which resist the change in pH on addition of small amount of acid or alkali and are called Buffer solution. For example a mixture of H₂CO₃ and HCO₃- is a natural buffer system which maintains the pH of blood. A buffer that is widely used in clinical laboratory and in biochemical studies in the physiological pH range is prepared from tris amino methane (hydroxy methyl) (THAM) [(HOCH₂)3CNH₂].
In order for a solution to act as a buffer it must have two components, one of which is able to neutralize acid and the other able to neutralize the base. Common buffer solutions are mixtures containing a
Weak acid and its conjugate base (one of its salt) called acidic buffer
eg:- CH₃OOH/CH₃COONa, H₂CO₃/Na₂CO₃, Boric acid/borax
Weak base and its conjugate acid (one of its salt) called basic buffer
Eg:- NH4OH/NH4Cl, Zinc hydroxide/ zinc chloride, Glycine/ glycine hydrochloride.