AbstractVarious gel permeation chromatography (GPC) factors affecting chromatogram interpretation have been studied. These include the variation of refractive index with polymer concentration and molecule size, the concentration effect, calibration curve selection, and column deterioration. Several assumptions inherent in GPC interpretation were found to be valid with reasonable limitations. The area under the GPC trace was found to be directly proportional to the weight of dissolved polymer, and the advantages of a method of calculating molecular weight averages by means of area rather than the conventional count height technique have been demonstrated. A synthetic broad distribution standard, composed of a wide molecular‐size range of narrow‐distribution standards, has been proposed for the diagnosis of the condition of GPC column syst