A large-volume on-column GC-cryotrapping-IR system was developed for injections of up to 100 μl of organic extracts. Considerable reduction of the solvent-and-water background and enhanced analyte detectability was achieved by using an open-split interface between the GC column and the IR detector and improving the leak-tightness of the system. The system was combined with solid-phase extraction to yield on-line SPE-GC-IR. With this set-up, sample volumes of only 20 ml sufficed to detect, and identify, microcontaminants in tap and surface water at the 0.1-1 μg/L level. Detection limits were on the order of 15 ng/L for tap water when using appropriate functional-group chromatograms. Or, in other words, SPE-GC-IR is a suitable technique for the screening of environmental water samples for functional groups, i.e. classes of compounds, of interest.