Abstract: 0.15g of NaCl was dissolved in 10 mL of the water sample in the headspace sample vial and acidity of the solution was adjusted to pH 5.0. It was then extracted ultrasonically for 28 min by a droplet (1 μL) of ionic liquid of 1-buty-3-methyl-imidazole hexafluorophosphate ［C4MIM］［PF6］ hanged at the end of the needle of the microinjector. Polychlorobiphenyls (PCB′s) in the ionic liquid droplet were then desorbed at 280 ℃ for 1 min in the gasification chamber having the inner diameter of its innerlined tube enlarged to 3.5 mm. The gasified PCB′s were introduced into the capillary chromatographic column, separated and determined by MS. Linearity for the PCB′s was kept in the range of 10-300 ng·L-1. Detection limits (3S/N) were found in the range of 1.2-2.3 ng·L-1. Eight samples of sea water were analysed by this method, and recovery was tested by adding mixed standard solution to these samples, giving values of recovery in the range from 81.5% to 104.2%.