Liquid Chromatograph Separate Measurement Flow Path
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Solution Overview
Problem
In liquid chromatography, measuring instruments like pH meters and conductivity meters are prone to contamination and pressure issues when placed on the analysis flow path, leading to inaccurate and slow confirmation of mobile phase preparation due to their poor pressure resistance and the need to stop the mobile phase flow for measurement, which increases the inner volume and measurement time.
Innovation Solution
A liquid chromatograph design with a separate measurement flow path and a status switching unit, such as a three-way valve or on-off valve, allows the mobile phase to flow only through the measurement path during preparation state confirmation, reducing system volume and pressure on the measuring instrument, and enabling quick and accurate measurement by isolating the measuring instrument from the analysis flow path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measuring instrument is arranged on the analysis flow path, then the preparation state of the mobile phase can be measured, but the measuring instrument is contaminated and deteriorates quickly
Solution Approach 1:
The flow path is divided into two separate segments: the analysis flow path for sample analysis and the measurement flow path for mobile phase preparation state measurement. The measuring instrument is placed on the measurement flow path, which is a separate branch from the analysis flow path. This segmentation allows the measuring instrument to access the mobile phase for measurement without being exposed to the contaminants present in the analysis flow path, thereby resolving the contradiction between measurement capability and instrument durability.
2Reliability
If the measuring instrument is arranged at the most downstream position, then pressure resistance requirements are met, but the inner volume increases and measurement time is extended
Solution Approach 1:
Instead of arranging the measuring instrument sequentially at the downstream end of the analysis flow path (one-dimensional arrangement), the invention creates a branched measurement flow path that connects to the analysis flow path at an intermediate position. This dimensional change in the flow path architecture allows the measuring instrument to be positioned in a separate branch, reducing the volume of mobile phase that needs to be displaced for measurement while still meeting pressure resistance requirements.
3Measurement precision
If the mobile phase flow is stopped for measurement, then accurate measurement is achieved, but the confirmation time is extended due to large system volume
Solution Approach 1:
The flow path is segmented into measurement and analysis pathways, allowing the measuring instrument to draw mobile phase from a separate measurement flow path with smaller volume. When measurement is required, only the small volume in the measurement flow path needs to be considered, not the entire analysis flow path volume. This segmentation enables faster flow cessation and quicker measurement execution while maintaining measurement accuracy.
Data Source
AI summary
A liquid chromatograph includes: a feeding unit configured to feed a mobile phase prepared for an analysis; an analysis flow path provided with an analytical column for separating a sample and a detector for detecting sample components separated with the analytical column; a sample injection part configured to inject the sample into the analysis flow path; a measurement flow path provided separately from the analysis flow path and provided with a measuring instrument for measuring a preparation state of the mobile phase; and a status switching unit configured to selectively switch between an analysis state in which all of the mobile phase the from feeding unit flows through the analysis flow path and a measurement state in which at least a part of the mobile phase from the feeding unit flows through the measurement flow path.