Liquid Chromatograph Column Switching Flow Rate Control
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Solution Overview
Problem
In liquid chromatography, column switching during successive analyses can cause damage due to sudden changes in mobile phase flow rates, especially when switching to a column requiring a higher target flow rate.
Innovation Solution
A liquid chromatograph control method and system that gradually increase the mobile phase flow rate to the target flow rate over stages when switching columns, using a column-protective method file to manage the flow rate transitions, reducing the risk of column damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mobile phase flow rate is suddenly increased to the target flow rate after column switching, then the analysis productivity is improved, but the column may be damaged
Solution Approach 1:
The system performs preliminary action by detecting column switching events before the analysis begins and pre-configuring a gradual flow rate increase schedule. The control unit creates a staged flow rate profile that increases from a lower initial rate to the target rate over multiple stages, preventing sudden pressure shocks to the column while maintaining analytical productivity.
Solution Approach 2:
The system applies dynamics by making the flow rate adjustable and variable rather than fixed. The mobile phase flow rate dynamically transitions from a lower initial rate to the target rate through multiple intermediate stages, allowing the system to adapt the flow conditions to protect the column during switching while achieving the desired analysis speed.
2Object-affected harmful factors
If the mobile phase flow rate is gradually increased in stages, then the column damage is reduced, but the analysis time is extended
Solution Approach 1:
The system applies partial action by implementing a moderate gradual increase strategy rather than an extremely slow ramp-up. The flow rate increases through multiple stages that are sufficient to protect the column but not excessively prolonged, balancing column protection with reasonable analysis time completion.
Solution Approach 2:
The system changes parameters by adjusting the flow rate through defined stages with specific time intervals. The control unit modifies the flow rate parameter dynamically, transitioning from initial to target rates through intermediate values, optimizing the balance between column protection and analysis efficiency.
Data Source
AI summary
To reduce damage to a column caused during column switching when performing successive analyses while switching columns, provided is liquid chromatograph control system 70 for analyzing a sample according to a schedule table where analysis conditions and execution order of a plurality of analyses are described. Control system 70 includes: schedule reader 66 for reading out two consecutively executed analysis conditions; column comparator 67 for comparing columns used in the two analysis conditions; insertion method file creator for creating an insertion method file so that the flow rate of a mobile phase sent to the column used in later one of the two analyses is increased in stages toward a flow rate determined for the later analysis, where the columns are different between the two analysis conditions; and a schedule table creator 63 for inserting the insertion method file into immediately before the later analysis in the schedule table.