Amphoteric substance ampholyte

The pH gradient is established with the aid of a mixture of low-molecular weight amphoteric substances (ampholytes). Such mixtures are manufactured by LKB (Ampholines), Pharmacia (Pharmalytes), etc. These ampholytes are synthetic zwitterionic species that differ from each other in their pl-values, and a set of ampholytes covers more or less uniform pi ranges from 2-3 to 10-11. They contain amino groups (basic groups) and carboxylic groups as well as acidic ones (Ampholines, Pharmalytes). 

Amphoteric substances, or ampholytes, are able to engage in neutralization reactions both with acids and bases (more precisely, both with hydrogen and hydroxyl ions). Aluminium hydroxide, for example, reacts with strong acids, when it dissolves and aluminium ions are formed ... 

Some compounds can donate and accept protons. They are called amphoteric substances, or ampholytes. The best-known example is water. It gives a proton according to Eq. (4.5) and accepts a proton according to (4.6) ... 

Substances having this dual nature are amphoteric and are often called ampholytes (from amphoteric electrolytes ). A simple monoamino monocarboxylic a-amino acid, such as alanine, is a diprotic acid when fully protonated—it has two groups, the —COOH group and the —NHj group, that can yield protons ... 

Amphoteric — a substance that can act both as an acid and a base - acid-base theories, subentry - base-antibase concept, -r ampholyte, - Bjerrum, Niels Jan-niksen, - capillary isoelectric focusing (CIEF), -+ metals. 

Ampholyte — A substance that can react both as an acid and as abase is called an ampholyte, or amphoteric compound. Usually this property refers to the - Bronsted acid-base theory. An example is HCOj which can act as a proton acceptor and as a proton donator. An ampholyte can be a zwitterion, as in case of amino acids in the range between pH = pJCai and pH = pfCa2, they exist as [+(H3N)HRC-COO-]. 

Some substance (like HS04, H2P04 , HP04-, NH3, H20 etc.) can function both as acids and bases, depending on the circumstances. These substances are called amphoteric electrolytes or ampholytes. 

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