Two 4-vinylimidazole-divinylbenzene (4VIm-DVB) polymers were synthesized and applied as sorbents for on-line solid-phase extraction (SPE) followed by liquid chromatography for analyzing polar compounds in aqueous samples. The new sorbents (4VIm-DVB) were compared to another sorbent that had been previously synthesized by our group (N-vinylimidazole-divinylbenzene (NVIm-DVB)) and to the commercial OASIS(R) HLB and Strata(TM) X. All the sorbents enabled 100 mL of sample to be on-line concentrated with good recoveries for the studied polar compounds. Real water samples were analyzed using NVIm-DVB and OASIS(R) HLB as SPE sorbent, for which the best results were obtained.