Cross-linking reagents, divinylbenzene (DVB) in polystyrene-type ion exchange resin precursors with chloromethyl substituents were determined by pyrolysis-gas chromatography (PY-GC) in aiding preliminary reduction of chlorine atoms in the samples. The characteristic peaks of DVB or its derivatives were completely separated on the pyrograms of the reduced precursors. The relative peak intensities (I-rel) of DVB or its derivatives were calculated from their peak area, and interpreted in terms of the amounts of cross-linking reagents introduced into the resin precursors synthesized by different synthetic pathways. (C) 1997 Elsevier Science Ltd.