Microfluidic CE-MS Metabolite Detection for Direct ATP Separation
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Solution Overview
Problem
Current methods for detecting metabolites like ATP are problematic due to poor retention by traditional liquid-chromatography, instability, and sensitivity to interconversion, leading to underdeveloped analytical techniques for LC/MS systems and indirect ATP level measurements.
Innovation Solution
A method using a capillary electrophoresis-mass spectrometry (CE-MS) system that includes contacting a sample with an uncoated or chemically-modified CE platform, separating metabolites by molecular weight and charge, and detecting them via mass spectrometry, integrating electrophoretic separation and electrospray ionization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional reversed-phase liquid-chromatography (RPLC) is used to separate ATP, then the separation process is simple and well-established, but ATP is poorly retained and cannot be effectively separated
Solution Approach 1:
The patent changes the separation parameters by switching from reversed-phase liquid chromatography to capillary electrophoresis, which separates compounds based on charge-to-size ratio rather than hydrophobicity. This parameter change enables effective retention and separation of ATP and related nucleotides that are poorly retained by traditional RPLC methods
Solution Approach 2:
The patent introduces an intermediary interface (spray chamber and electrospray ionization source) that connects the aqueous capillary electrophoresis separation system to the mass spectrometer detection system. This intermediary enables efficient transfer of charged analytes from the CE capillary to the gas phase for MS detection without requiring traditional LC elution
2Reliability
If ion-pairing chromatography or passivation is used to separate ATP, then ATP retention is improved, but the system becomes problematic for LC/MS due to contamination and reduced sensitivity
Solution Approach 1:
The patent extracts the problematic ion-pairing reagents and passivation layers from the system by using bare, uncoated capillaries in capillary electrophoresis. This eliminates the contamination and sensitivity issues associated with ion-pairing chromatography while maintaining effective ATP separation through charge-based electrophoretic mobility differences
Solution Approach 2:
The patent substitutes the mechanical/chromatographic separation mechanism (ion-pairing chromatography) with an electrophoretic separation mechanism based on electric field-driven migration. This substitution maintains separation effectiveness while eliminating the contaminants that reduce MS detection sensitivity
3Productivity
If luminescence-based assays are used to measure ATP levels, then the measurement is simple and rapid, but only indirect ATP levels are obtained without simultaneous readout for analogues
Solution Approach 1:
The patent implements a universal CE-MS platform that can simultaneously detect and quantify multiple nucleotide metabolites (ATP, ADP, AMP, and their analogues) in a single analysis. The mass spectrometer provides universal detection capability for all charged nucleotide species, replacing multiple specific assays with one multi-functional system
Solution Approach 2:
The patent introduces mass spectrometry as an intermediary detection method that bridges the gap between simple luminescence assays and complex chromatographic methods. MS provides direct, simultaneous quantification of multiple nucleotide species while maintaining rapid analysis times, eliminating the need for indirect luminescence measurements
4Reliability
If coated chip capillary electrophoresis is used, then the system is more robust and reusable, but ATP and nucleotide analogues do not migrate in the coated capillaries
Solution Approach 1:
The patent inverts the conventional approach by using uncoated, bare capillaries instead of coated capillaries. This inversion allows charged nucleotide analytes to migrate freely through the capillary under the electric field, while the capillary stability and reuse capability are maintained through careful control of electroosmotic flow and buffer conditions
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 allows for direct and efficient detection of metabolites like ATP, providing accurate diagnostic and therapeutic monitoring for diseases associated with aberrant nucleotide signaling.
Implementation Method 1
separating the metabolites by molecular weight and/or charge in one or more capillaries using CE
Implementation Method 2
detecting the eluted metabolite by mass spectrometry analysis
Implementation Method 3
detecting the eluted metabolite by mass spectrometry analysis
Data Source
AI summary
The present disclosure relates to methods of detecting metabolites using a microfluidic capillary electrophoresis-mass spectrometry (CE-MS) system. The metabolites can be useful to diagnosis diseases or disorders, as well as to monitor therapeutic efficacy of compounds used to treat these diseases or disorders.