Biomolecule Monitoring via Dialysis Cell and Periodic Sampling
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Solution Overview
Problem
The challenge in monitoring biomolecule separations by mass spectrometry is the incompatibility of the mobile phase with common ionization techniques, leading to contamination, ion suppression, and reduced sensitivity, especially when dealing with biomolecules that require careful handling to maintain their native conformations.
Innovation Solution
A system and method that employs a periodic sampling device to transfer discrete aliquots from the chromatography column effluent into a separately provided fluidic stream, using a dialysis cell with a semi-permeable membrane to remove low molecular weight components, and an electrospray emitter, which minimizes dialysate consumption and allows for efficient dialysis independent of the chromatography column flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mobile phase is used directly in mass spectrometry, then the separation process is maintained, but contamination and ion suppression occur reducing sensitivity
Solution Approach 1:
A dialysis cell with semi-permeable membrane is introduced as an intermediary device between the chromatography column and mass spectrometer. The membrane allows small molecules (salts, buffers) to pass through while retaining biomolecules, effectively mediating the incompatibility between mobile phase components and mass spectrometry detection
Solution Approach 2:
Low molecular weight components (salts, buffers, small molecules) are extracted and removed from the mobile phase through the dialysis membrane, separating them from the biomolecules of interest before mass spectrometry analysis
2Productivity
If high flow rate is used from chromatography column, then separation speed is improved, but dialysis efficiency decreases
Solution Approach 1:
The system segments the flow into two independent streams: a high-flow chromatography stream for rapid separation and a low-flow dialysis stream for efficient dialysis. The periodic sampling device transfers aliquots from the high-flow stream to the low-flow dialysis stream, allowing both high productivity and high dialysis efficiency to coexist
Solution Approach 2:
A periodic sampling device is used to transfer discrete aliquots from the chromatography column effluent into the dialysis cell at optimized intervals, enabling the dialysis process to operate at low flow rates while the chromatography column operates at high flow rates
3Reliability
If dialysis is performed at low flow rate, then dialysis efficiency is optimized, but analysis time increases
Solution Approach 1:
Instead of continuously running dialysis at low flow rate, the system uses periodic sampling to transfer aliquots at optimized intervals. This allows the dialysis cell to operate at efficient low flow rates while the overall analysis time is controlled by adjusting the sampling frequency
Solution Approach 2:
The system performs preliminary separation at high flow rate through chromatography, then transfers selected aliquots to the dialysis cell. This preliminary action reduces the total volume requiring dialysis, thereby reducing the overall dialysis time while maintaining efficiency
4Productivity
If biomolecules are handled aggressively to improve separation, then productivity increases, but native conformation is lost
Solution Approach 1:
Different quality conditions are applied to different parts of the system: aggressive separation conditions in the chromatography column for high productivity, and gentle dialysis conditions in the dialysis cell for maintaining native conformation. The periodic sampling device connects these two different quality environments
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 approach enables efficient and prompt identification of biomolecules emerging from the chromatography column, reducing contamination and ion suppression, while maintaining the native structure of biomolecules and optimizing dialysis efficiency, even at low flow rates compatible with electrospray emitters.
Implementation Method 1
a dialysis cell with a semi-permeable membrane to remove low molecular weight components
Implementation Method 2
an electrospray emitter... When one of these ionisation techniques is used, ions and ambient neutral gas molecules are drawn into the vacuum system
Data Source
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AI summary
A means of monitoring biomolecule separations by mass spectrometry is described. The mixture to be separated is introduced into a first fluidic stream, which then passes through a chromatography column 103. Small samples are periodically taken from the first fluidic stream as it leaves the chromatography column and injected into a first branch of a second fluidic stream 212. Low molecular weight components detrimental to the efficient operation of the mass spectrometer are removed by an in-line dialysis cell 224. A second fraction of the second fluidic stream 214 acts as the dialysate. In a second and preferred system provided in accordance with the present teaching, the first fraction of the second fluidic stream is further split downstream of the sampling mechanism 215 through the use of a three-way connector 302. Approximately 0.3 to 5 microliters per minute continues through the dialysis cell and thereafter to the electrospray emitter 238 of the mass spectrometer. Desirably, the electrospray emitter 238, dialysis cell 224, and fluidic split 302 are provided as a demountable assembly 400. In a third embodiment of a system provided in accordance with the present teaching, the dialysate is provided separately as a third fluidic stream.