NMR Pulse Train Selective Excitation for Multicomponent Analysis
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Solution Overview
Problem
Existing methods for analyzing the content and purity of chemical samples, particularly those with multiple components, face challenges in achieving accurate chemically selective excitation, especially when dealing with complex target frequency profiles.
Innovation Solution
The method involves using an excitation profile derived from a known or estimated response function characteristic of at least one component in the sample, applying nuclear magnetic resonance (NMR) spectroscopy to selectively excite magnetic resonance from specific components in a sample, and constructing a pulse train by mathematically transforming the source waveform to achieve selective excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency-selective pulses are used for selective excitation, then selectivity for single resonance frequency is improved, but difficulty increases when target frequency profile is complex
Solution Approach 1:
The patent transforms the excitation approach by changing from direct frequency-domain selective pulses to time-domain waveforms. By applying inverse Fourier transformation to convert frequency profile requirements into time-domain pulse shapes, the system achieves complex frequency selectivity through parameter transformation rather than complex pulse design
Solution Approach 2:
The patent replaces the traditional mechanical approach of designing complex frequency-selective pulse sequences with a mathematical transformation approach. The inverse Fourier transform algorithm substitutes for iterative pulse optimization, converting a difficult spectral design problem into a straightforward mathematical operation
2Adaptability or versatility
If conventional NMR methods are used for multicomponent analysis, then general applicability is maintained, but accurate chemically selective excitation becomes challenging
Solution Approach 1:
The patent performs preliminary action by obtaining the response function of the target component before the actual analysis. This pre-acquired spectral information is stored and used to generate customized excitation waveforms, allowing the system to adapt to different components without redesigning the entire excitation scheme
Solution Approach 2:
The patent introduces the response function as an intermediary element between the NMR system and the sample analysis. This intermediary contains the characteristic spectral information of the target component and serves as the basis for generating selective excitation waveforms, bridging the gap between general NMR capabilities and specific chemical selectivity
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 accurate identification and quantification of chemical components in multicomponent mixtures, enhancing the selectivity and effectiveness of NMR analysis by selectively exciting specific components within the sample.
Implementation Method 1
a magnetic response of the sample to pulsed fields is measured by a detection apparatus
Implementation Method 2
the sample is immersed in a very strong, highly uniform static magnetic field, allowed to come to magnetic equilibrium, and then exposed to a sequence of one or more strong brief pulses of oscillatory magnetic field
Data Source
AI summary
The present document describes methods and systems for exciting magnetic resonance in a sample using trains of pulsed, oscillating magnetic fields that are modulated in their phase and amplitude according to a source waveform derived from the known or estimated magnetic response of a sample. Also disclosed are methods and systems for acquiring a response signal from the sample wherein data acquisition events are synchronized or interleaved with said modulated pulse trains. Further disclosed are methods and systems for identifying one or more of the presence, absence, amount, and concentration of a target substance in a sample. Also disclosed is a magnetic resonance device which uses such pulse trains and synchronized acquisition to improve the selectivity of magnetic resonance data.