Autosampler Clog Detection via Pressure Variation Analysis
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Solution Overview
Problem
In liquid chromatography, clogs in the analysis system, often caused by precipitation, are difficult to locate due to undetectable system pressure increases, and existing autosamplers struggle to accurately determine clog locations in the needle.
Innovation Solution
An autosampler with a clog determiner that measures the variation in liquid sending pressure when switching between injecting and loading modes, using a ratio of pressure variation to a preset threshold to accurately identify clogs in the analysis flow path, facilitating the specification of clog locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the liquid sending pressure is monitored to detect clogs in the analysis system, then the clog detection capability is improved, but the ability to specify the exact location of the clog deteriorates
Solution Approach 1:
The analysis system is segmented into multiple sections: the autosampler needle, the analysis flow path, and the separation column. By monitoring pressure variations specifically when switching between loading and injecting modes, the system can identify which segment contains the clog based on the magnitude and pattern of pressure changes, thereby locating the clog while maintaining reliable detection.
2Ease of operation
If an absolute value of the variation value of liquid sending pressure is used for clog determination, then the clog detection is simplified, but erroneous determination occurs when the liquid sending pressure is large
Solution Approach 1:
The determination parameter is changed from the absolute variation value of liquid sending pressure to the ratio of the variation value to the liquid sending pressure. This normalization approach allows the system to maintain accurate clog determination across different operating conditions and pressure levels, preventing erroneous determinations while preserving ease of operation through automated ratio calculation.
3Reliability
If the needle is cleaned or exchanged frequently to prevent clogs, then the reliability of the analysis system is improved, but the productivity and operational efficiency deteriorate
Solution Approach 1:
The system implements self-monitoring through automated pressure variation analysis during mode switching. The clog determiner automatically detects clogs in the needle or flow path and provides location information, enabling targeted maintenance only when necessary. This eliminates the need for frequent preventive cleaning or needle exchange, maintaining high reliability while preserving productivity by intervening only when actual clogs are detected.
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
The autosampler effectively identifies and specifies clog locations in the analysis system, preventing erroneous determinations and enabling timely maintenance, such as cleaning or needle exchange.
Implementation Method 1
a liquid sending pressure of a liquid sending pump that sends a mobile phase in the analysis flow path
Data Source
AI summary
An autosampler is switched selectively between an injecting mode where a sampling flow path is incorporated into an analysis flow path of a liquid chromatograph and a loading mode where the sampling flow path is not incorporated into the analysis flow path and injects a sample into the analysis flow path at a position farther upstream than a separation column by being switched to the injecting mode with the sample held in the sampling flow path, and includes a clog determiner configured to acquire a sending liquid pressure of a liquid sending pump that sends a mobile phase in the analysis flow path, obtain a variation value of the liquid sending pressure when the injecting mode and the loading mode are switched and determine presence or absence of a clog in a system incorporated into the analysis flow path in the injecting mode based on the obtained variation value.