Single-Stroke Solvent Pumping for Continuous Chromatography Flow
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Solution Overview
Problem
Conventional solvent delivery systems for chromatography face issues such as large size, high cost, flow perturbations, pressure pulses, and band broadening due to refilling events in pumps, leading to noise and reduced chromatographic data quality.
Innovation Solution
A solvent delivery system using two single plunger pumps with synchronized operational cycles, controlled by processors to ensure continuous flow by offsetting refilling phases with delivery phases, eliminating interruptions and reducing mixing requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional single stroke pump is used, then the pump structure is simple, but the chromatographic run must stop once the plunger reaches the end of its travel for refilling
Solution Approach 1:
The pump system is segmented into multiple plungers (at least two) that operate in sequence. Each plunger handles a portion of the pumping cycle, allowing one plunger to deliver solvent while another refills, thereby eliminating the need to stop the chromatographic run for refilling while maintaining a relatively simple pump structure.
2Reliability
If two individual pump heads are used to provide continuous flow, then continuous solvent delivery is achieved, but the system size and cost increase
Solution Approach 1:
Multiple plungers are merged into a single integrated pump head assembly rather than using separate pump heads. The plungers share common infrastructure including the pump chamber, outlet check valve, and fluid pathways, which reduces the overall system volume and component count while maintaining continuous flow capability.
3Adaptability or versatility
If multiple pumps with multiple plungers are used to deliver separate solvents, then solvent mixing capability is achieved, but flow perturbations and pressure pulses occur during refill events
Solution Approach 1:
The plungers are synchronized to operate in a continuous cycle where at least one plunger is always in the delivery phase while others refill. This continuous operation eliminates interruptions and maintains stable flow and pressure throughout the chromatographic run, preventing the perturbations and pulses that occur during refill events in conventional systems.
Solution Approach 2:
The plungers execute periodic stroke cycles in a coordinated sequence. By carefully timing the periodic actions of multiple plungers, the system ensures that refill events do not coincide with analyte elution from the chromatography column, thereby maintaining flow stability and composition consistency during the critical detection phase.
4Ease of operation
If conventional pump arrangements with refill events are used, then pump operation is simple, but detection noise and band broadening occur due to pressure perturbations
Solution Approach 1:
The synchronized periodic strokes of multiple plungers are timed so that refill events occur outside the analyte elution window. This allows simple pump operation to be maintained while eliminating the pressure perturbations that cause detection noise and band broadening during the critical measurement phase.
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
Achieves continuous solvent flow without interruptions, minimizing pressure and compositional perturbations, reducing system size and cost, and enhancing chromatographic data quality by eliminating band broadening and noise.
Implementation Method 1
The mobile phase enters the single stroke pump 100 and is displaced by the plunger 104 out the outlet 110
Implementation Method 2
An inlet check valve 108 is provided at the inlet 106 to prevent flow of the mobile phase back out the inlet 106
Data Source
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AI summary
The exemplary embodiments control solvent pumps so that system flow is constant. One or more controllers may control the flow rate produced by the pumps over time. The one or more controllers control a first pump so that, as the first pump is refilling, a second pump maintains a sufficient flow rate to compensate for the lost flow due to the refilling event. In some exemplary embodiments, the one or more controllers control the timing of the refilling event for the first event such that the refilling event overlaps with the equilibrating of the chromatography column with solvent(s) from the second pump. Similarly, the one or more controllers control the timing of the refilling event for the second pump such that the refilling event overlaps with the equilibrating of the chromatography column.