Isobaric Mass Labeling for Accurate Analyte Quantification
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Solution Overview
Problem
Conventional tandem mass spectrometry using isobaric mass labels often provides inaccurate results for complex samples due to co-eluting contaminants with the same mass to charge ratio as the target analyte, leading to poor quantification of analytes in complex mixtures like proteins.
Innovation Solution
A method involving differential labeling of samples with isobaric mass labels, followed by selective ion fragmentation and mass spectrometry, where ions of specific mass to charge ratios are selected and fragmented to isolate intact mass labels, allowing for accurate quantification by filtering out contaminating peptides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional tandem mass spectrometry using isobaric mass labels is used to analyze complex samples, then the analysis can be performed with standard methods, but co-eluting contaminants with the same mass to charge ratio interfere with accurate quantification
Solution Approach 1:
The patent segments the detection process into multiple stages: first selecting precursor ions by m/z ratio, then isolating specific ion populations, fragmenting them, and finally detecting fragment ions. This multi-stage segmentation allows the system to distinguish target analytes from co-eluting contaminants that have the same precursor m/z ratio but different fragmentation patterns, thereby resolving the interference problem while maintaining quantification accuracy.
2Productivity
If isobaric mass labels are used to label multiple samples simultaneously, then throughput is improved, but selectivity among different samples is reduced
Solution Approach 1:
The patent uses isobaric mass labels that act like different 'colors' in the mass spectrometric domain - all labels have the same overall mass (isobaric) but contain distinct mass marker groups with unique m/z ratios. This allows multiple samples to be labeled simultaneously with different labels (analogous to different colors) while maintaining the ability to distinguish them through their unique mass marker signatures in the fragmentation spectrum, thus preserving both throughput and differentiation accuracy.
3Loss of time
If standard tandem mass spectrometry is used for analyzing labeled analytes, then the method is simple and fast, but quantification accuracy deteriorates due to contaminants with identical mass to charge ratio
Solution Approach 1:
The patent performs preliminary isolation and selection of specific ion populations before fragmentation and detection. By pre-isolating ions with specific m/z ratios and selecting particular precursor ions before fragmentation, the system eliminates interfering contaminants in advance. This preliminary action ensures that only target analyte ions proceed to fragmentation and detection, maintaining quantification accuracy without significantly increasing analysis time since the additional selection steps are integrated into the existing tandem MS workflow.
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 the selectivity and accuracy of analyte quantification by ensuring that only the target analyte's mass marker groups are detected, improving the specificity and sensitivity of the analysis in complex samples.
Implementation Method 1
introducing the analysis mixture into a mass spectrometer; selecting ions having a first mass to charge ratio equivalent to an ion of the target analyte labelled with a specific number of mass labels
Implementation Method 2
fragmenting ions of the first mass to charge ratio into a plurality of fragment ions, wherein a proportion of the plurality of fragment ions comprise at least one intact mass label
Data Source
AI summary
The disclosure provides a method for assaying for a target analyte, comprising providing a plurality of samples which may comprise the target analyte, wherein each sample is differentially labelled with a mass label or a combination of mass labels, wherein the mass labels are from a set of mass labels, wherein each mass label is an isobaric mass label comprising a mass spectrometrically distinct mass marker group, such that the samples can be distinguished by mass spectrometry and determining from the mass spectrum the quantity of the target analyte in each sample.