AbstractA rapid and sensitive method to determine volatile organohalides in different types of waters has been developed. The chromatographic system is based on the resolving power of the glass capillary column and the high sensitivity of the electron capture detector. The capillary columns were connected to the detector so that the eluate from the column is mixed with thermostatted purge gas to minimize band broadening due to dead volumes. The low column bleeding and decreased band spreading from capillary columns enhance the sensitivity to very low levels: 1 fg (10−15g) for carbon tetrachloride, despite dilution of the column eluate by the purge gas.The water samples of 100 ml were extracted with 1 to 10 ml n‐pentane which is the most practical alkane with respect to purity. When using high water to pentane ratios corrections had to be made, due to low extraction yield, to get accurate quantifications.A column with Carbowax 400 stationary phase permits direct tap water injection. The water peak concealed the substances eluated after CHCl3and CHBrCl2.The gas chromatographic separation of haloforms in tap water could be shortened to 30 seconds using a 10 m SE–52 column with an increased film thickness.Besides tap water and seawater, industrial waste water from a pulp mill was analyzed. Ten different halogenated organic compounds, ranging from 1 ng/I to 760 μg/I, were quantified in the different waters. Bromoform, which had not previously been found in seawater, was detected.Chromatogram of a standard mixture containing 11 organohalides. Stationary phase, SE‐52; 33 m × 0.3 mm i.d. inj. temp. 200°, column temp. 50°, interface 250°, detector temp. 250°. Helium carrier gas flow rate, 36 cm/s, scavenger'gas flow 30 ml/min.Split ratio 1:20, 1 = CH2CI2, 2 = CHC13, 3 = CH3CC13, 4 = CC14, 5 = CHCICCI2, 6 = CHBrCI2, 7 = CBrC13, 8 = CHBr2Cl, 9 = CCl2CC12, 10 = CHCl2