Abstract: Device for connecting a first duct of a very small diameter, such as for instance a needle or a capillary column, to a second duct, wherein the device comprises a receiving part and a sealing element, wherein the receiving part is provided with a duct bore in which the first duct is slidably receivable, wherein the receiving part is also provided with a sealing-element bore which intersects the duct bore and in which the sealing element is slidably received, wherein the sealing element is provided with a recess, wherein the sealing element is adapted to assume a sealing position in which the duct bore is sealed, and is adapted to assume a connecting position in which the two duct bore parts on either side of the sealing-element bore are in fluid connection with each other via the recess, wherein the sealing element is biased in the sealing position by a spring under spring action.