Capillary Tube Plug Sealing to Eliminate HPLC Dead Volume
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing capillary tube connection systems in high-performance liquid chromatography (HPLC) face issues with dead volume creation due to axial tolerance differences and the risk of sealing element deformation, especially when using thinner capillary tubes with smaller diameters, leading to unreliable connections and potential damage.
Innovation Solution
A capillary tube connection system featuring a plug with a sealing element having a convex first end section and an annular shape with a larger second inner diameter, which can be compressed to securely fit capillary tubes of varying diameters, using a pressure piece to apply axial force and prevent the sealing element from detaching during disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing elements are pressed into conical receptacle openings with high pressure to ensure tightness, then sealing reliability is improved, but the sealing elements deform and become difficult to shift axially onto the capillary tube
Solution Approach 1:
The sealing element is divided into two functional parts: a conical front region for creating the seal in the receptacle opening, and a cylindrical rear region for easy axial mounting onto the capillary tube. This segmentation allows each region to perform its specific function without interfering with the other.
Solution Approach 2:
Different regions of the sealing element have different geometries optimized for their specific functions: the front region has a conical profile for sealing, while the rear region has a cylindrical profile for easy axial insertion. This local quality differentiation resolves the contradiction between sealing effectiveness and ease of mounting.
2Reliability
If the sealing position is offset rearward from the capillary tube end surface to ensure sealing, then sealing reliability is improved, but dead volume is created that adversely affects HPLC performance
Solution Approach 1:
The sealing action is transferred from the axial dimension to the radial dimension. The conical front region of the sealing element creates a radially inward pressure against the receptacle opening wall, achieving sealing without requiring axial offset, thus eliminating dead volume while maintaining sealing reliability.
3Measurement precision
If capillary tubes with smaller diameters are used to improve resolution, then analytical performance is improved, but the risk of sealing element deformation and connection reliability increases
Solution Approach 1:
The sealing element is made from an elastomeric material that provides flexible sealing. This flexibility allows the sealing element to adapt to small variations in capillary tube outer diameters without deforming or damaging the connection, ensuring reliable sealing even with thinner capillary tubes used for high-resolution chromatography.
4Strength
If the sealing element is made from metal to ensure durability, then strength is improved, but the sealing element cannot compensate for axial tolerance differences in receptacle openings
Solution Approach 1:
The sealing element is made from an elastomeric material that changes its physical parameters (compressibility, elasticity) under axial load. This allows the sealing element to compensate for axial tolerance differences in receptacle openings by deforming elastically, while still providing durable and reliable sealing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides a compact, reliable, and easy-to-assemble sealing system that compensates for axial tolerances and prevents sealing element detachment, ensuring a stable fluid flow and reducing the risk of capillary tube damage, while allowing for secure connections with different capillary tube diameters.
Implementation Method 1
an extremely high, radially inward pressure is exerted by means of an attachment screw onto the front region of the sealing element, so that the sealing position is realized. Through the high pressure deformation of the sealing element and the capillary tube can be generated
Implementation Method 2
Through the high pressure deformation of the sealing element and the capillary tube can be generated, wherein the sealing element is pressed with its front edge in an annular shape into the outer periphery of the capillary tube
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The present invention is directed to a plug for connecting capillaries. The plug comprises at least one capillary tube (20) comprising at least one first inner diameter (21) and an open end section. Moreover, at least one generally plug-shaped sealing (30) comprises at least one second inner diameter (31). The sealing has a first end section (32) of generally convex shape and/or flat face adapted to seal the end section (22) of the capillary tube (20) when connected. The sealing (30) can additionally or optionally comprise at least one second inner diameter (31) being at least in part larger than the first inner diameter (21) of the capillary tube (20) when the sealing is in an uncompressed state. Additionally or alternatively the sealing can comprise at least one second inner diameter (31) being at least in part larger than the first inner diameter (21) of the capillary tube (20) when the sealing is in an uncompressed state. Further, there is at least one pressure piece (40) that is adapted to exert at least axial pressure and/or force to at least a part of the sealing (30) towards a second end section (33) of the sealing (30) oriented opposite to the first end section (32) of the sealing (30). The pressure piece (40) is adapted to host at least the first end section (32) of the sealing (30) in an aperture (41) in abutment with the end section of the capillary tube (20) so that the first inner diameter (21) of the capillary tube (20) and the second inner diameter (31) of the sealing (30) are aligned.