Electrokinetic Calibrant Delivery for Mass Spectrometers
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Solution Overview
Problem
Time-of-flight mass spectrometers face mass accuracy drifting due to thermal expansion/contraction, and existing calibration mechanisms are cumbersome, leading to mechanical failures and reduced sensitivity.
Innovation Solution
The use of electrokinetic pumps to provide electroosmotic flows of calibrant and analyte solutions to electrospray ionization emitters, allowing for efficient and rapid switching between analytical and calibrant sprays, eliminating the need for cumbersome mechanical mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical baffle controlled by a stepper motor is used to select effluent from calibrant or analyte electrospray streams, then switching between calibration and analysis modes is achieved, but the mechanism becomes cumbersome and introduces multiple points of mechanical failure
Solution Approach 1:
The patent replaces the mechanical baffle and stepper motor system with an electrokinetic pump system that uses electrical fields to control fluid flow. The electrokinetic pumps can be actuated electronically to deliver either calibrant or analyte solutions to the electrospray emitter, eliminating mechanical moving parts and potential failure points while maintaining the ability to switch between calibration and analysis modes.
Solution Approach 2:
The patent uses electrokinetic pumping, which is an electro-hydraulic mechanism, to control the delivery of calibrant and analyte solutions. The electrokinetic pumps use electrical fields to generate fluid flow through electroosmosis, providing a non-mechanical means of controlling effluent selection and delivery to the mass spectrometer.
2Measurement precision
If a mechanical baffle mechanism is used to block effluent from one electrospray stream, then selection between calibrant and analyte is achieved, but optimal positioning of the analyte sprayer is inhibited resulting in reduced sensitivity
Solution Approach 1:
The patent replaces the mechanical baffle system with independently controlled electrokinetic pumps for each spray source. This allows the analyte sprayer to be positioned optimally for sensitivity without mechanical interference, while the electrokinetic pumps provide electronic control over which solution is delivered to the emitter, maintaining mass accuracy through precise calibration capability.
3Reliability
If the actuating voltage is turned off to one spray source while the other sprays, then switching between modes is achieved, but flow continues resulting in solution buildup at the sprayer causing unstable spraying
Solution Approach 1:
The patent uses electrokinetic pumps that can be rapidly actuated and deactivated through electrical control. When switching between calibrant and analyte delivery, the inactive pump can be completely stopped by removing its actuating voltage, preventing solution buildup and ensuring stable spraying. The electronic control allows for rapid switching without the delays associated with mechanical systems.
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 enhances mass accuracy by enabling efficient solid-state switching and rapid delivery of calibrant ions, reducing mechanical failures and improving sensitivity, while allowing for precise calibration of mass spectrometers.
Implementation Method 1
actuating an electrokinetic pump and thereby providing an electroosmotic flow of a calibrant solution from a calibrant solution source to an electrospray ionization emitter
Implementation Method 2
a plume of calibrant ions is emitted from the electrospray ionization emitter toward an inlet orifice of a mass spectrometer
Data Source
AI summary
An electrokinetic pump can be used to deliver calibrant (“lock mass”) ions to a mass spectrometer for calibration of a mass spectrometry system. Electrokinetically controlled calibrant delivery can help to eliminate the need for the more cumbersome mechanisms that are often used for ion delivery. In addition, electrokinetically controlled calibrant delivery can provide for a more user-friendly system in which a calibrant solution can be packaged into a disposable cartridge. Furthermore, when implemented in a microfluidic format, electrokinetically controlled calibrant delivery can be coupled with an electrokinetically controlled separation system, such as capillary electrophoresis (CE), to allow efficient solid-state switching between analytical and calibrant sprays.