Injection systems for sample testing for luminometers

An injection system in combination with a luminometer, comprising a movable carrier, there being at least two stations between which the carrier can be moved, one station being a liquid loading station and another station being a liquid dispensing station, a dispenser assembly mounted on the carrier and including an injector needle arranged, when at the liquid dispensing station, to pass through an aperture in a part of the luminometer aligned with a test sample container therein, when the container is in a test chamber with which a photo-multiplier device communicates, and sealing means for preventing the light from passing through said aperture into the luminometer, both when the needle extends through said aperture and when the needle has been withdrawn from said aperture, wherein the sealing means comprises first and second parts each having a through bore therein, the first part being in use fixed relative to the luminometer with its through bore aligned with said aperture in the luminometer and one end of the first part in light sealing relationship with said aperture, and the first part having a piston movable therein in a direction transverse to its through bore for selectively blocking the passage of light through its through bore, the second part being supported relative to the carrier and having one end in permanent light sealing relationship with the needle, the other end of the second part being movable into light sealing relationship with the other end of the first part as the needle approaches said aperture in the luminometer, said light sealing relationship occurring before the needle reaches the piston so that the piston can be moved to allow the needle access to said aperture after the first and second parts have been moved into light sealing relationship with one another.