Flow Metering Device for Multi-Dimensional Liquid Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current flow splitting technologies in multi-dimensional liquid chromatography systems, such as resistive tubing elements, struggle to maintain uniform flow rates due to variations in viscosity, temperature, and flow path changes, leading to inconsistent analysis and potential damage to second-dimension separation systems like mass spectrometers.
Innovation Solution
A multi-dimensional liquid analysis system with a flow metering device that selectively controls the flow rate by bridging a discontinuity in the outlet flow path at desired time intervals, ensuring precise control of split flows and preventing unswept volumes between the split point and detection means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If resistive tubing elements are used for flow splitting, then flow division is achieved, but uniform flow rate control is poor due to viscosity and temperature variations
Solution Approach 1:
The patent replaces the mechanical resistive tubing system with a valve-based flow control system. The valve mechanism uses a moving member that can be precisely positioned to control flow rate, substituting the passive mechanical resistance of tubing with an active valve control mechanism. This allows for more precise and reliable flow rate control that is not susceptible to viscosity and temperature variations affecting tubing resistance.
Solution Approach 2:
The patent changes the control parameter from fixed resistive properties of tubing to adjustable valve opening parameters. By controlling the position of the moving valve member, the flow rate can be dynamically adjusted and maintained at desired levels despite changes in fluid properties such as viscosity and temperature. The valve provides direct mechanical control over flow parameters rather than relying on indirect resistive effects.
2Object-affected harmful factors
If flow rate is reduced to match second-dimension detector capacity, then detector overload is prevented, but chromatographic resolution is reduced
Solution Approach 1:
The patent divides the total flow into separate segments using the valve mechanism. One portion of the flow is directed to the second-dimension detector at a controlled, reduced rate that prevents overload, while another portion can be directed elsewhere or recirculated. This segmentation allows the system to maintain high total flow for good chromatographic resolution while delivering only the necessary fraction to the detector at an appropriate rate.
Solution Approach 2:
The valve acts as an intermediary device between the high-flow chromatographic system and the low-capacity detector. It mediates the flow rate mismatch by selectively restricting flow to the detector while allowing the main system to operate at optimal flow rates for resolution. The valve serves as a buffer that protects the detector from overload without compromising the performance of the chromatographic separation system.
3Manufacturing precision
If mobile phase contains buffer salts for first-dimension separation, then separation performance is improved, but mass spectrometer fouling increases
Solution Approach 1:
The valve system enables extraction of a small, controlled portion of the mobile phase containing buffer salts and directs it to the mass spectrometer. By taking out only the necessary fraction for detection and controlling its flow rate, the system maintains the buffer salts in the main flow for separation performance while minimizing their introduction to the mass spectrometer, thereby reducing fouling.
Solution Approach 2:
The patent applies local quality control by allowing different flow conditions in different parts of the system. The main mobile phase flow maintains high buffer salt concentration for optimal separation performance in the first-dimension column, while the localized flow to the mass spectrometer is controlled to be low and manageable. The valve creates local flow differentiation that satisfies both the separation requirements and the detector protection requirements.
Data Source
AI summary
A multi-dimensional liquid analysis system includes a first dimension system and a second dimension system, wherein outflow from the first dimension system is separated at a flow splitter under controlled conditions. The flow splitter separates the first dimension outflow into first and second split outlet flows, with one of the split outlet flows being metered to a designated flow rate with a flow metering device disposed downstream from the flow splitter. The flow metering device selectively closes or opens an outlet flow path to define a volumetric flow rate along that outlet flow path, so that the other split outlet flow is correspondingly controlled.