Electrospray Array Stabilizes LC-MS Signal
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Solution Overview
Problem
Liquid Chromatography Mass Spectrometry (LC-MS) systems face significant signal variability at analytical flow rates due to turbulence and disruptions in gas flow and droplet formation during electrospray ionization, particularly at low analyte concentrations and short monitoring periods.
Innovation Solution
A system and method utilizing an electrospray source with a pressurized waste reservoir to control the flow rate of the liquid flow to the electrospray ionization outlet, featuring an array of electrospray emitters and a counter electrode, with adjustable electric field strength and nebulization gas pressure to stabilize ion formation and desolvation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrospray ionization is used at analytical LC flow rates, then analyte ionization can be achieved, but signal variability increases due to turbulence and disruptions in gas flow and droplet formation
Solution Approach 1:
The patent divides the single electrospray emitter into an array of multiple emitters (e.g., 5-1000 emitters). This segmentation allows the total liquid flow to be distributed across multiple smaller droplet streams, reducing the impact of turbulence and disruptions in any single emitter on overall signal stability.
Solution Approach 2:
The patent introduces a pressurized waste reservoir that applies backpressure to the liquid flow system. By controlling the pressure parameter in the waste reservoir, the flow rate to each emitter in the array is stabilized, reducing variability in droplet formation and gas flow turbulence, thereby improving signal stability.
2Productivity
If high gas flow is used to desolvate charged droplets at analytical flow rates, then ionization efficiency can be maintained, but turbulence in the gas flow increases causing signal variability
Solution Approach 1:
By segmenting the ionization process across multiple emitters, each handling a smaller portion of the total flow, the gas flow required per emitter is reduced. This decreases turbulence in the gas flow while maintaining overall ionization efficiency through the combined output of all emitters in the array.
Solution Approach 2:
The patent uses a pressurized waste reservoir that applies backpressure exceeding what would be needed in a conventional single-emitter system. This excessive pressure control stabilizes the liquid flow to each emitter, enabling efficient ionization with reduced gas flow turbulence.
3Quantity of substance
If flow rate is increased to improve signal intensity, then more analyte can be ionized, but turbulence and disruptions in droplet formation increase causing signal variability
Solution Approach 1:
The patent segments the total analyte load across multiple emitters in an array. Each emitter handles a smaller flow rate, maintaining stable droplet formation, while the combined output from all emitters provides sufficient analyte quantity for detection without the turbulence associated with high flow rates in a single emitter.
Solution Approach 2:
The pressurized waste reservoir controls the flow rate parameter to each emitter by applying backpressure. This maintains optimal flow conditions for stable droplet formation at each emitter while the array collectively processes sufficient analyte quantity.
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 solution provides stable and consistent ionization, reducing signal variability and improving the accuracy of mass-to-charge ratio analysis, as demonstrated by reduced ion intensity variability compared to traditional high flow sources.
Implementation Method 1
an electrospray emitter includes a platinum wire to provide a high voltage to the second portion of the flow at the electrospray emitter
Implementation Method 2
A flow rate of the second portion of the liquid flow can be substantially determined by a pressure of the pressurized waste reservoir
Implementation Method 3
Ionization techniques, such as electrospray ionization, can form charged droplets which are then desolvated in a gas flow
Data Source
AI summary
A system for analyzing a sample includes a chromatographic device, an electrospray source, and a mass resolving device. The chromatographic device is configured to separate components of the sample as a function of retention time within a chromatographic column. The electrospray source is configured to direct a first portion of a flow from the chromatographic device via a waste outlet to a pressurized waste reservoir, direct a second portion of the flow to an electrospray ionization outlet to form a spray, and charge and desolvate the spray to form ions of the components of the sample. A flow rate of the second portion of the liquid flow is substantially determined by a pressure of the pressurized waste reservoir. The mass resolving device configured to receive the ions and characterize the mass-to-charge ratio of the ions.