The prevention of distortion in ultrathin-layer polyacrylamide gel isoelectric focusing

Although isoelectric focusing patterns in ultrathin layers of polyacrylamide gel are distorted by the presence of salts, such as ammonium persulfate, this reagent is commonly used to promote polymerization of the gel. The amount of ammonium persulfate can be reduced but this causes the formation of sloppy gels or incomplete polymerization. A method is described here in which an ultrathin polyacrylamide gel is formed on a polyester sheet using ammonium persulfate in the absence of ampholyte. After complete polymerization, the ammonium persulfate is washed out and ampholyte is allowed to diffuse into the gel. Subsequent isoelectric focusing is then free from distortion caused by the presence of ammonium persulfate.