A hollow-membrane fibre is used for the introduction of gaseous compounds into a flow-injection system. The sampling system consists of a certain length of asymmetric hollow-fibre membrane in which an acceptor stream is stopped for a fixed period of time. The analyte permeates from the surrounding environment through the membrane and is accumulated in the acceptor solution, then pumping is resumed. The method is tested for the determination of carbon disulphide in ambient air. The detection range of the method is from 3 to at least 30 mg l−1.