Coiled Passive Solvent Mixer for LC Baseline Noise Reduction
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Solution Overview
Problem
Liquid chromatography systems experience significant periodic baseline noise due to reciprocating pumps, which affect detection sensitivity and compound identification, particularly in reverse phase liquid chromatography using trifluoroacetic acid, and current mixers are inefficient in reducing this noise.
Innovation Solution
A mixer with an inlet, outlet, and flow channels featuring a coiled channel as an offset volume to increase radial dispersion, reducing fluid propagation delay and enhancing mixing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a reciprocating pump system is used to deliver mobile phase, then the pump can provide controlled flow rate and composition, but periodic baseline noise is generated that reduces detection sensitivity
Solution Approach 1:
The pump stroke is divided into multiple smaller sub-strokes using multiple outlet channels (first, second, third outlet channels) that deliver fluid at different phases. This segmentation allows the periodic noise from each individual stroke to be distributed and averaged across multiple output streams, reducing the amplitude of baseline noise while maintaining controlled flow rate delivery.
Solution Approach 2:
Multiple outlet channels delivering fluid at different phases are merged into a single combined output stream. The merging of these phase-differentiated flows causes the periodic noise components to interfere destructively, significantly reducing the overall baseline noise while preserving the controlled flow rate characteristic of the reciprocating pump.
2Ease of operation
If current mixers (e.g., packed beads columns) are used to mix solvents, then mixing function is provided, but periodic baseline noise is substantially reduced inefficiently
Solution Approach 1:
The mixing process is segmented into multiple parallel flow paths with different phase delays. Each outlet channel provides a separate mixing path that processes the mobile phase at a different phase of the pump cycle, allowing noise reduction through phase differentiation while maintaining effective mixing function.
Solution Approach 2:
The mixer device performs multiple functions simultaneously: it mixes the mobile phase components, delays fluid propagation to create phase differences, and reduces periodic baseline noise. This multi-functionality is achieved by integrating the mixing channels with phase-delay characteristics directly into the mixer structure.
3Stability of the object's composition
If solvent packets are concatenated at low pressure, then composition control is achieved, but compositional noise remains significant
Solution Approach 1:
The system utilizes the periodic action of the reciprocating pump strokes and intentionally introduces phase delays between multiple outlet channels. By synchronizing the mixing process with the periodic pump action and creating controlled phase differences, the system converts the periodic composition variations into a form that averages out noise when combined, improving compositional stability.
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
Substantially reduces periodic noise, increasing detection sensitivity and improving compound identification by near-complete elimination of noise, especially in complex mixtures.
Implementation Method 1
The offset volume includes a coiled channel, wherein a radial dispersion of a fluid flow through the coiled channel is increased
Data Source
AI summary
Described is a mixer for a liquid chromatography system. The mixer includes an inlet, an outlet, a first flow channel, and a second flow channel. The inlet receives a fluid flow to be mixed and the outlet provides the mixed fluid flow. Each of the two flow channels is coupled between the inlet and the outlet. The second flow channel includes an offset volume that delays fluid propagation through the second flow channel relative to the first flow channel. The offset volume includes a coiled channel which increases radial dispersion and decreases axial dispersion of a fluid flowing through the offset volume, thereby enabling a further reduction in periodic noise in a detector baseline signal as compared to known split flow mixers for liquid chromatography systems.