Differential Refractometer Gradient Chromatography Flow Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current differential refractometers face challenges in accurately measuring analyte concentration during gradient chromatography due to changes in solvent refractive index, leading to errors and obscuration of analyte signals.

Innovation Solution

A differential refractometer system that includes a solvent delay volume, eluent flow meter, solvent flow regulator, instrument controller, and optical bench, which maintains a flow rate ratio between the eluent and solvent, ensuring the refractive index difference is only due to analyte concentration by matching solvent composition in both the sample and reference cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If gradient chromatography is performed to separate analytes with different properties, then separation capability is improved, but refractive index measurement accuracy deteriorates due to solvent composition changes

Engineering Contradiction:

Improveseparation capabilityVSAvoidrefractive index measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system divides the flow into two separate paths: one through the chromatography column (sample cell) and one through the solvent delay volume (reference cell). This segmentation allows independent control and measurement of each stream's refractive index, enabling accurate differential measurements even when solvent composition changes during gradient elution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts the flow rate through the solvent delay volume to match the changing solvent composition in the chromatography column. By changing the flow rate parameter in real-time, the reference cell maintains the same solvent refractive index as the sample cell, isolating analyte detection from solvent composition variations.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If flow rate changes are made during gradient elution to optimize separation, then separation efficiency is improved, but signal accuracy deteriorates due to refractive index fluctuations

Engineering Contradiction:

Improveseparation efficiencyVSAvoidsignal accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system uses flow meters to continuously monitor the flow rates through both the chromatography column and the solvent delay volume. This feedback information is used by the controller to dynamically adjust the solvent delay volume flow rate, ensuring it always matches the chromatography column flow rate despite changes during gradient elution, thereby maintaining signal accuracy.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from a static flow configuration to a dynamic one where the solvent delay volume flow rate is continuously adjusted to match the chromatography column flow rate. This dynamic adaptation allows the system to maintain measurement accuracy throughout the entire gradient elution process, regardless of flow rate changes.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If a simple refractometer design is used to reduce complexity, then device simplicity is improved, but measurement reliability deteriorates in gradient conditions

Engineering Contradiction:

Improverefractometer design simplicityVSAvoidmeasurement reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The solvent delay volume acts as an intermediary component that replicates the solvent composition changes in the chromatography column. By introducing this intermediate element, the system maintains a reference stream that matches the sample stream's solvent conditions, enabling reliable differential measurements without requiring complex real-time solvent composition analysis.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution allows for precise analyte concentration measurement in gradient chromatography by isolating refractive index changes to analyte presence, reducing errors and enhancing signal clarity.

Implementation Method 1

an optical bench configured to measure, in response to receiving from the instrument controller a signal indicating that the flow rate ratio has been achieved, a difference between a refractive index of the eluent present in the sample cell and a refractive index of the solvent present in the reference cell

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS11579079B2Differential refractometer for gradient chromatography

Publication Date: 2023.02.14 WYATT TECHNOLOGY CORP

AI summary

The present disclosure describes a differential refractometer for gradient chromatography. In an exemplary embodiment, the differential refractometer includes a solvent delay volume, an eluent flow meter coupled to an eluent inlet of a sample cell, a solvent flow regulator coupled to an outlet of the solvent delay volume and coupled to a solvent inlet of a reference cell, an instrument controller configured to receive the eluent flow rate from the eluent flow meter, configured to receive the solvent flow rate from the solvent flow regulator, configured to receive a flow rate ratio from a flow rate ratio data source, wherein the flow rate ratio indicates a ratio of the eluent flow rate to the solvent flow rate, and an optical bench configured to measure a difference between a refractive index of the eluent present in the sample cell and a refractive index of the solvent present in the reference cell.