A method for the determination of insulin by paper chromatography

A method for the determination of insulin potency using circular chromatography is described. The eluted spots are measured with respect to a standard which is run simultaneously with the unknown. The results of this determination do not differ significantly from those obtained by biological assay, at least for preparations with a potency higher than 19 I.U./mg on a moisture-free basis. For the determination of less pure samples the use of a standard insulin of corresponding purity is recommended. The precision of the method compares with that of a biological assay with 250 rabbits. Protamine and excess of zinc do not interfere with the determination.