An easily-assembled, heat resistant connector for releasably joining end portions of three capillary tubes for use in chromatography without interrupting flow or interfering with chromatographic results comprises a main body, and a glass insert which has first, second and third hollow legs that are connected together at a central portion, and a connector that connects each leg of the glass insert to a capillary tube. Each leg of the glass insert extends outwardly from the central portion towards an open end portion, and each leg has an inboard bore with a taper that receives and end portion of one of the capillary tubes. The taper is wider near the open end portion of the leg and narrower near the central portion. The connectors are mounted on the main body and a sealing ferrule is provided in each connector for making a seal between the capillary tubes and the legs of the glass insert. An adjusting screw in each connector provides for independently adjusting the pressure against each of the sealing ferrules to insure that an efficient seal is made between each capillary tube and a leg of the glass insert.