An extra dimension of polymer analysis: ion mobility spectrometry-mass spectrometry (IMS-MS) separates ions according to their size in the gas phase, allowing differentiation of linear and cyclic polymeric isomers. This analytical technique is a rapid and sensitive method for assessing cyclic polymer purity in one step. As highly pure cyclic polymers are crucial for adequately assessing architecture dependent properties, IMS-MS offers great promise in the characterization of this unique class of polymers.