TOF Mass Spectrometer Electrode Distance Adjustment
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Solution Overview
Problem
High-resolution mass determination in MALDI time-of-flight mass spectrometry is hindered by initial velocity spread and distance variations between the sample support and the first accelerating electrode, leading to poor mass resolution and sensitivity, especially when using thick matrix crystal samples or irregular sample surfaces.
Innovation Solution
Adjusting the distance between the sample surface and the first accelerating electrode using digital camera images and optical projection systems to maintain precise positioning, allowing for accurate calibration and voltage control to ensure consistent ion acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sample support is movable to accommodate different samples, then the versatility and ease of operation are improved, but the distance variation between sample surface and accelerating electrode worsens, leading to poor mass resolution
Solution Approach 1:
The patent replaces mechanical distance adjustment mechanisms with an electric field-based solution. A control electrode is introduced that generates an electric field to compensate for distance variations automatically, eliminating the need for precise mechanical positioning while maintaining consistent ion acceleration conditions across different sample positions
Solution Approach 2:
The patent dynamically adjusts the electric field parameters (voltage on control electrode) based on the actual distance between sample surface and accelerating electrode. By changing the electric field strength and distribution, the system compensates for distance variations and maintains consistent ion focusing conditions regardless of sample position
2Adaptability or versatility
If thick matrix crystal samples are used to accommodate various analytes, then the adaptability is improved, but the distance variation and surface irregularities worsen, leading to poor mass resolution and sensitivity
Solution Approach 1:
The patent replaces mechanical precision positioning with electric field compensation. The control electrode creates an adjustable electric field that compensates for the irregularities introduced by thick matrix crystals, allowing versatile sample analysis while maintaining high mass resolution through field-based focusing
Solution Approach 2:
The patent introduces dynamic adjustment of the electric field parameters to adapt to different sample thicknesses and surface conditions. The control electrode voltage can be modified in real-time to optimize ion focusing for each specific sample configuration, maintaining high resolution across diverse analyte types
3Ease of operation
If the distance between sample surface and accelerating electrode is not precisely controlled, then the ease of operation is improved, but the ion focusing conditions worsen, leading to poor mass accuracy and resolution
Solution Approach 1:
The patent replaces complex mechanical distance control systems with a simple electric field adjustment mechanism. The control electrode allows distance compensation through voltage adjustment alone, greatly simplifying operation while maintaining sub-micrometer distance precision and achieving mass accuracy better than one part per million
Solution Approach 2:
The control electrode serves as an intermediary element between the sample support and the accelerating electrode. It mediates the distance variation by creating an adjustable electric field that compensates for positional differences, enabling simple operation while maintaining precise ion focusing 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
Achieves mass accuracy of less than one part per million and maintains high mass resolution and sensitivity by ensuring consistent ion focusing conditions across multiple samples, even with varying sample thickness and surface irregularities.
Implementation Method 1
using digital camera images and optical projection systems to maintain precise positioning
Implementation Method 2
an optical projection system which directs light at a non-perpendicular incidence angle onto sample (2)
Implementation Method 3
The ions are accelerated in the ion source by electric fields to energies of around 10 to 30 kiloelectronvolts, injected axially into the flight path
Implementation Method 4
A pulse of light in the order of a nanosecond in duration from a laser focused onto the sample surface vaporizes a small amount of the matrix substance in a quasi-explosive process, forming a plasma
Implementation Method 5
forming a plasma, the analyte molecules also being transferred into the initially tiny plasma cloud
Implementation Method 6
detected time-resolved at the end of the flight path, because heavy ions fly slower than light ions
Data Source
AI summary
In a time-of-flight mass spectrometer having an ion source with a first accelerating electrode, a distance between the surface of a sample and the first accelerating electrode is maintained at a predetermined distance which is critical for determining the mass and quantity of ions generated by the ion source. A digital image of the sample surface is obtained with a digital camera and a predetermined characteristic of the digital image is determined. The predetermined characteristic is then used to compute an adjustment amount by which the sample surface is moved to maintain the predetermined distance. Determining the predetermined characteristic can be simplified by projecting a light pattern onto the sample surface at an angle and determining the predetermined characteristic from the digital image of the pattern.