This International Standard specifies a gas-chromatographic method for determining monomeric diisocyanates such as toluene diisocyanate1), hexamethylene diisocyanate, isophorone diisocyanate2), diphenylmethane diisocyanate3) and other diisocyanates in isocyanate resins as defined in Clause 3 and in solutions prepared from such resins, insofar as these are used in the formulation of paints and similar coating materials.