Liquid Chromatograph Detector Flow Cell with Low Resistivity Fluororesin
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Solution Overview
Problem
In liquid chromatography, non-metallic materials like PEEK resin are used to prevent sample adsorption, but they have high electric resistance, leading to static electricity accumulation and noise interference in detectors due to poor discharge of electric charges.
Innovation Solution
A detector design with a flow cell having a second wetted member made of a non-metallic material with lower electric resistivity than the tube's PEEK resin, allowing for easy discharge of electric charges through grounding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-metallic materials like PEEK resin are used for wetted members, then sample adsorption is prevented, but electric charges accumulate due to high electric resistance
Solution Approach 1:
The invention uses a composite structure where the flow cell housing is made of PEEK resin (non-metallic material with high electric resistance) and the flow passage is made of fluororesin (non-metallic material with low electric resistance). This composite material approach allows the system to benefit from both materials: the PEEK housing prevents sample adsorption while the fluororesin flow passage allows electric charges to discharge, resolving the contradiction between preventing sample adsorption and avoiding electric charge accumulation.
2Reliability
If PEEK resin is used for the flow cell, then chemical resistance is improved, but electrostatic noise increases due to poor charge discharge
Solution Approach 1:
The flow cell is constructed as a composite structure with PEEK resin for the housing (providing chemical resistance) and fluororesin for the flow passage (providing low electric resistance for charge discharge). This composite approach maintains the chemical resistance benefits of PEEK while eliminating the electrostatic noise problem by using fluororesin in the flow passage where liquid contacts occur.
3Measurement precision
If the light-receiving element is placed close to the flow cell, then detection accuracy is improved, but noise from electric charges increases
Solution Approach 1:
The invention converts the potentially harmful effect of electric charge accumulation into a beneficial situation by using fluororesin material in the flow passage that actively discharges electric charges. This allows the light-receiving element to be placed close to the flow cell for high detection accuracy without suffering from electrostatic noise, as the fluororesin continuously dissipates charges that would otherwise interfere with the detector.
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
Prevents sample adsorption and reduces electrostatic noise in chromatograms by facilitating the discharge of electric charges, improving signal accuracy in liquid chromatography.
Implementation Method 1
the flow cell has a passage surface formed by a second wetted member including a non-metallic material having a lower electric resistivity than the first wetted member
Implementation Method 2
the electric charges which have entered the flow cell can be easily discharged by grounding the wetted member in the flow cell
Implementation Method 3
the components in the sample flowing through the tube and the flow cell along with the mobile phase can be prevented from adsorbing to the inner surface of the wetted members in the tube and the flow cell
Implementation Method 4
when a liquid flows through a tube at high speeds, static electricity occurs due to the friction between the inner surface of the tube and the liquid, causing the inner surface of the tube to be electrically charged, a phenomenon called 'flow electrification'
Data Source
AI summary
A detector (50) for a liquid chromatograph includes a tube (56) and a flow cell (52) arranged so that a mobile phase and a sample exiting from a column (10) in a liquid chromatograph (100) flow through the tube into the flow cell which is configured to allow for detection of a component in a sample flowing within the flow cell. The tube includes a first wetted member (56) made of a PEEK resin material. The flow cell has a passage surface formed by a second wetted member (521) including a non-metallic material having a lower electric resistivity than the first wetted member. The use of those wetted members facilitates the discharging of electric charges from the flow cell while preventing adsorption of sample components to the inner surface of the flow cell.