Sample Aspiration Cannula Washing Guide for Liquid Chromatography

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Solution Overview

Problem

Conventional liquid chromatography samplers face challenges in accurately injecting small sample quantities due to carry-over issues, which lead to measuring errors in LCMS systems, and current washing procedures are complex and time-consuming.

Innovation Solution

A sample delivery system with a sample aspiration cannula and a guide element designed as a washing device, allowing for efficient cleaning of both the inside and outside of the cannula, reducing carry-over and enabling precise sample dosing and quick contamination removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional washing procedures are used to remove carry-over, then contamination is reduced, but the process becomes complex and time-consuming

Engineering Contradiction:

Improvecontamination removalVSAvoidwashing procedure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The guide element is designed to perform multiple functions simultaneously: it guides the sample aspiration cannula during injection and serves as a washing device during retraction. The guide element includes a washing solvent delivery system that cleans the cannula outer surface during the retraction movement, merging guidance and washing functions into a single integrated structure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The washing action occurs continuously during the cannula retraction movement from the sample receptacle. The washing solvent is delivered along the cannula outer surface throughout the retraction path, ensuring continuous cleaning without requiring separate washing steps, thereby simplifying the overall process while maintaining effective contamination removal.

Inventive Principle:

Principle #20Continuity of useful action

2Measurement precision

If complex washing procedures are applied to reduce carry-over, then measuring accuracy is improved, but the sample delivery cycle time increases

Engineering Contradiction:

Improvemeasuring accuracyVSAvoidsample delivery cycle time

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The guide element combines guidance and washing functions, allowing the cannula to be cleaned during its normal retraction movement. This eliminates the need for separate washing steps, reducing cycle time while maintaining effective carry-over removal through continuous washing solvent delivery during retraction.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The washing action is performed continuously during the cannula retraction phase, utilizing the existing movement time efficiently. This continuous washing approach ensures thorough contamination removal without extending the overall cycle time, as the cleaning occurs concurrently with the necessary cannula retraction motion.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If the sample aspiration cannula is cleaned after injection, then carry-over is reduced, but additional time is required for cleaning

Engineering Contradiction:

Improvecarry-over reductionVSAvoidcleaning time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The washing solvent is delivered to the cannula outer surface during the retraction movement, performing the cleaning action preliminarily as the cannula returns to its starting position. This integrates the cleaning function into the existing operational cycle rather than adding a separate post-injection cleaning step, thereby reducing carry-over without increasing total processing time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The cleaning action occurs continuously during the cannula retraction phase, utilizing the necessary movement time for cleaning purposes. This continuous washing during retraction ensures effective carry-over reduction while eliminating dedicated cleaning time, as the cleaning and retraction operations are performed simultaneously.

Inventive Principle:

Principle #20Continuity of useful action

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 system effectively minimizes carry-over and contamination, allowing for precise sample delivery with reduced cycle time and simplified handling, enhancing the accuracy and efficiency of chromatographic measurements.

Implementation Method 1

An entirety of the distal end is wetted, preferably flowed around, by the washing solvent

Methodology Applied

Scientific EffectWetting: Wetting

Data Source

PatentUS11480551B2Sample injector and sampling method, in particular for liquid chromatography

Publication Date: 2022.10.25 PROLAB INSTR GMBH

AI summary

A sample delivery system for liquid chromatography is provided. The sample delivery system includes: a sample receptacle; a sample aspiration cannula for aspirating a sample located in the sample receptacle, the sample aspiration cannula being directed using a drive in a direction towards the sample receptacle so that a tip at a distal end of the sample aspiration cannula is immersed in the sample; and a guide element for the sample aspiration cannula provided above the sample receptacle, the guide element being designed as a washing device. The sample aspiration cannula can be retracted using the drive at least so far from the sample receptacle such that the distal end of the sample aspiration cannula may be cleaned in the washing device.