Abstract: A cap assembly for a gas chromatography injection port includes a two-piece septum. The two-piece septum includes a syringe seal for sealing an injection needle and a duckbill seal for sealing the injection port when the needle is not inserted. The syringe seal includes three annular ribs in its aperture. At the aperture base is a sealing rib that provides the main sealing function for the syringe seal. Just above the sealing rib is a stress-relief rib. At the top of the aperture is a wiping rib. The wiping rib wipes dust on the needle exterior so that it does not enter the aperture. Dust entering the aperture can be retained in the relatively large dust pocket between the wiping rib and the strain-relief rib. The septum is held in place by a septum nut that has a recess above the wiping rib for holding dust removed from the needle by the wiping rib. A washer in the recess prevents the syringe seal from deforming into the recess.

Abstract: A septum for an injection port of a gas chromatograph includes interlocked syringe and duckbill seals. The syringe seal prevents fluid leakage during injection by syringe. The duckbill seal prevents fluid leakage after the syringe needle is withdrawn from the septum. A spring clip is used to urge the duckbill closed as the needle is withdrawn. An advantage of this two component septum is that the duckbill slit can be precisely formed in the duckbill seal before the seals are engaged.

Abstract: A pipette assembly for automatic pipetting machines including a pipette tip and a pipette tip holder having a mandrel and a seal. The mandrel includes a plug portion which is adapted to engage a top end portion of the pipette tip, and a cylindrical seat portion proximate its bottom end. The seal is a unitary, resilient member having a cylindrical base portion, an upwardly flaring skirt portion, and an opening receptive to the seat portion of the mandrel. An inner surface of the base portion of the seal is provided with a pair of sealing ribs, one of which serves as a pivot for the skirt portion.

Abstract: A precise volume of sample liquid is injected by inserting a syringe into the vaporizing chamber of the injection assembly for a gas chromatograph by performing the entire injection including withdrawal of the syringe in such a short time that essentially none of the liquid is vaporized while in the needle.