Acid-free paper Acid-free paper Acid-free paper is paper that if infused in water yields a neutral or basic pH (7 or slightly greater). It can be made from any cellulose fiber as long as the active acid pulp is eliminated during processing. It is also lignin- and sulfur-free. Acid-free paper addresses the problem of preserving documents and artwork for long periods. Paper made from wood-based pulp that has not had its lignin removed turns yellow, becomes brittle, and deteriorates over time. When exposed to light and/or heat, the molecules in the acidic paper will break down even faster. Acidic wood-pulp paper became
Immobilized pH gradient gradient instability and poor sample loading capacity associated with carrier ampholyte pH gradient. Commercial precast IPG gels are available. Immobilized pH gradient Immobilized pH gradient (IPG) gels are the acrylamide gel matrix co-polymerized with the pH gradient, which result in completely stable gradients except the most alkaline (>12) pH values. The immobilized pH gradient is obtained by the continuous change in the ratio of "Immobilines". An "Immobiline" is a weak acid or base defined by its pK value. Immobilized pH gradients (IPG) are made by mixing two kinds of acrylamide mixture, one with Immobiline having acidic buffering property and other