The evaluation of heterogeneous polymeric species by a selective, dual detector size-exclusion chromatography setup can provide accurate results on the incorporation of specific functional groups in copolymers as a function of the molar mass distribution. However, when non-UV-absorbing species are used in copolymerization reactions, the dual detector method becomes less reliable. By interfacing a Fourier transform infrared (FUR) spectrometer with size-exclusion chromatography (SEC), the problem can be overcome, making it possible to map non-UV-absorbing species as a function of the molar mass distribution. Coupling takes place via a solvent-evaporation stage, which delivers the mobile phase as a dry, solvent-free polymeric film onto a germanium disk. In this article, styrene and methyl methacrylate were grafted onto epoxidized natural rubber (ENR50) and analyzed by SEC. The accuracy of FTIR as a suitable detector was evaluated by comparing results from a dual detector SEC setup and FTIR coupled to SEC. FTIR proved to be a successful detector for the analysis of non-UV-absorbing species. This was consequently followed by the characterization of methyl methacrylategrafted ENR50. From the relevant data, Gram-Schmidt and contour plots could be made to indicate the incorporation of methyl methacrylate into the grafted epoxidized natural rubber as a function of the molar mass distribution. (C) 2003 Wiley Periodicals, Inc.