The use of carbamylated charge standards for testing batches of ampholytes used in two- dimensional electrophoresis

A method of testing batches of ampholytes is presented. By using carbamylated charges standards to co-electrophorese with the protein sample in the first-dimension isoelectric focusing gel, one can monitor, after running and staining the second-dimension sodium dodecyl sulfate (SDS) slabs gel, the continuity of the pH gradient. Charge standards can also be used to check the reproducibility of the pH gradient among batches of ampholytes and to modify the new batch with a small amount of a narrow range ampholyte to assure reproducibility of experiments. Ampholytes for comparison were obtained from three major manufacturers.