Fraction Collector Switching for Peak Loss Prevention
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Solution Overview
Problem
In preparative liquid chromatography, using multiple fraction collectors in parallel leads to peak diffusion and incomplete collection due to channel length issues when connected in series, and switching between collectors can result in peak loss if not managed properly.
Innovation Solution
A system with a switching valve and controller that switches between fraction collectors only when the number of unused collection containers falls below a certain threshold, ensuring peak collection is complete before switching to prevent partial peak loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple fraction collectors are connected in series to the detector outlet, then the number of available collection containers increases, but the channel length increases causing peak diffusion and wider peak width
Solution Approach 1:
The system divides the collection function into multiple parallel fraction collectors (first, second, and subsequent collectors) instead of using a single long channel in series. Each collector has its own independent channel from the detector, segmenting the collection process into parallel operations that avoid cumulative channel length increases.
2Length of moving object
If multiple fraction collectors are provided in parallel, then peak diffusion is prevented by equalizing channel lengths, but peak loss occurs when switching between collectors during peak collection
Solution Approach 1:
The switching valve is configured to switch between fraction collectors only during periods when no peak collection is being performed (baseline periods). This preliminary planning of switch timing prevents peak loss by ensuring that switching operations do not interrupt the collection of peak portions.
3Productivity
If the switching valve is switched during peak collection, then collection containers can be utilized more efficiently, but a part of the peak is left in the channel and cannot be collected
Solution Approach 1:
The controller monitors the detector signal to determine when peaks are present and when the baseline is stable. Based on this feedback, the switching valve is controlled to switch only during baseline periods when no peak is being collected, preventing peak loss while maintaining efficient container utilization.
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 approach ensures accurate and complete collection of peaks by switching fraction collectors only when unnecessary containers are depleted, preventing peak diffusion and loss, thereby enhancing the recovery rate.
Implementation Method 1
a separation column provided downstream of the injector on the analysis channel for separating components in the sample injected into the mobile phase
Implementation Method 2
a detector for detecting peaks of components separated by the separation column
Data Source
AI summary
A preparative liquid chromatograph including an analysis channel (2), an injector (6), a separation column (8), a detector (10), a plurality of fraction collectors (14-1 to 14-n), a switching valve (12) that switches fraction collectors (14-1 to 14-n) to be connected to the outlet of the detector (10) among the plurality of fraction collectors (14-1 to 14-n), and a controller (16) for controlling operations of the plurality of fraction collectors (14-1 to 14-n) and the switching valve (12). In a case where the number of remaining unused collection containers of the fraction collector in use, which is connected to the outlet of the detector, falls below the number of buffers which is an integer of two or more, the controller (16) is configured to switch the switching valve (12) while the fraction collector in use is not performing a peak collection operation.