ISO 11344:2016 describes a method for the determination of the molecular mass, expressed as polystyrene, and the molecular-mass distribution of polymers produced in solution which are completely soluble in tetrahydrofuran (THF) and which have a molecular-mass range from 5 ? 103 to 1 ? 106. It is not the purpose of this International Standard to explain the theory of gel permeation chromatography.