CAPILLARY ASSEMBLY USEFUL AS CONNECTING CAPILLARY
There is provided a capillary assembly suitable for connecting various components of an analytical measuring device, for example a liquid chromatograph or a capillary electrophoresis device, to each other. Specifically, this involves reinforcing the fragile tubing by the addition of PEEK or steel sleeves and/or embedding the tubing in an injection-molded resin such that the tubing is not exposed directly to operator handling and manipulation. Further functional improvement is obtained by including additional components inside the resin. Thereby a versatile and robust capillary assembly is achieved.
1 . A method for producing a capillary assembly, preferably a fused silica assembly, said method comprising:
introducing a capillary with sleeves that cover the capillary ends into a forming tool, said sleeves being adapted to closely fit the outer diameter of the capillary, and
molding a plastic material, preferably an elastic plastic material, within the forming tool thereby coating the capillary and sleeves with the plastic material; wherein the plastic material exclusively coats the capillary and a part of the sleeves, leaving a non-coated area of the sleeves.
2 . The method of claim 1 , where the sleeves are made from PEEK or steel or a combination of two concentric sleeves where a smaller inner sleeve of PEEK is inserted inside a larger sleeve of steel.
3 . The method of claim 1 , wherein molding the material is achieved by heating the plastic material beyond the softening temperature for bringing it in its softening range and making it soft.
4 . The method of claim 1 , wherein the plastic material is realized as a pre-formed part that gets adapted to the shape of the capillary and/or of the forming tool.
5 . A capillary assembly comprising:
a capillary, preferably a fused silica capillary, having a first end and a second end;
sleeves covering the ends of the capillary, said sleeves being adapted to closely fit the outer diameter of the capillary; and
a molded plastic coating, preferably from an elastic plastic material, exclusively coating the capillary and a part of the sleeves, leaving a non-coated area of the sleeves.
6 . The capillary assembly of claim 5 , wherein the sleeves are of PEEK or PEEK derivative, steel, or a combination of steel and PEEK wherein a smaller PEEK sleeve is inserted inside a larger steel sleeve.
7 . A capillary assembly of claim 5 wherein the assembly has been given an outer shape that fits to a counter-part in order to facilitate its subsequent installation in and use with an analytical measuring instrument.
8 . A capillary assembly of claim 5 wherein the capillary is filled with stationary phase resin (i.e. chromatography material) such that the assembly becomes a chromatography column.
9 . A capillary assembly of claim 8 wherein a heating element is embedded along with the chromatography column.