Biocompatible Tubing for Liquid Chromatography Systems

A tube and fitting system for use in a liquid chromatography system, comprising:

• a) a tube comprising:
• i) an outer layer having an inner surface and an outer surface, and having a first and a second end, wherein at least one of the first and second ends of said outer layer comprises a tip portion, wherein the tip portion comprises a polymer;
• and ii) a biocompatible inner layer having a passageway therethrough and having a first and a second end, wherein said inner layer is located within said outer layer;
• and b) a fitting comprising a first ferrule and a second ferrule, wherein the first ferrule comprises a metal and the second ferrule comprises a polymer, wherein the first ferrule is adapted to hold the tube by the outer layer and the second ferrule is adapted to seal the tube on the tip portion.

A fitting assembly for use in an analytical instrument system comprising:

• a) a tube comprising:
• i) an outer layer having an inner surface and an outer surface, and having a first and a second end, wherein at least one of the first and second ends of said outer layer comprises a tip portion, wherein the tip portion comprises a polymer;
• and ii) a biocompatible inner layer having a passageway therethrough and having a first and a second end, wherein said inner layer is located within said outer layer;
• b) a nut having a first end and a second end, and having a passageway therethrough, wherein said passageway has an internally tapered portion and a lip proximal said second end of said nut, and wherein said second end of said nut has an externally threaded portion;
• c) a ferrule having a first externally tapered end and a second end and having a passageway therethrough, wherein said first externally tapered end of said ferrule is adapted to securely engage with said tapered portion of said passageway in said nut;
• and
• d) a ferrule tip having a first externally tapered end, a central portion, and a second externally tapered end, wherein said first externally tapered end and said central portion define a first lip and said second externally tapered end and said central portion define a second lip, and wherein said first end of said ferrule tip is adapted to abut with said second end of said ferrule within said passageway of said nut, and said first lip of said ferrule tip securely engages said lip of said nut.