Multiplexed Mass Spectrometry for Resolving Vitamin D Metabolites
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Solution Overview
Problem
Current methods for measuring vitamin D metabolites in clinical settings, such as radioimmunoassay, do not separately resolve 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3, making it difficult to determine the source of nutritional deficiencies, and existing mass spectrometry methods often require derivatization which may not accurately reflect biological activity.
Innovation Solution
A method involving mass spectrometry that processes multiple test samples differently with isotopic variants of Cookson-type derivatizing agents, such as PTAD and 13C6-PTAD, to generate distinct ions for each sample, allowing for the simultaneous detection and quantification of vitamin D metabolites like 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 in a multiplex sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If radioimmunoassay is used to measure vitamin D metabolites, then the measurement can be performed in clinical settings, but it cannot separately resolve 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3
Solution Approach 1:
The patent applies segmentation by using isotopically labeled internal standards (25OHD2-d3 and 25OHD3-d3) that are distinct from the native vitamin D metabolites. This allows the mass spectrometer to separately detect and quantify 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 based on their different mass-to-charge ratios, resolving the limitation of radioimmunoassay while maintaining clinical applicability
Solution Approach 2:
The patent introduces isotopically labeled internal standards as intermediaries to enable precise measurement. These labeled standards (25OHD2-d3 and 25OHD3-d3) serve as mediators that allow the mass spectrometer to distinguish between different vitamin D metabolites through their unique mass signatures, providing both ease of operation and high measurement precision
2Measurement precision
If existing mass spectrometry methods are used, then vitamin D metabolites can be detected, but derivatization is required which may not accurately reflect biological activity
Solution Approach 1:
The patent applies preliminary action by adding isotopically labeled internal standards (25OHD2-d3 and 25OHD3-d3) to the samples before any processing steps. This early introduction of standards ensures they undergo the same extraction and analysis conditions as the native metabolites, providing accurate quantification without requiring derivatization that could alter biological activity
Solution Approach 2:
The patent changes the measurement parameter from derivatized products to native vitamin D metabolites by using mass spectrometry with isotopic labeling. This parameter change allows direct measurement of the biologically active forms without chemical modification, maintaining reliability while achieving precise detection through the unique mass-to-charge ratios of the labeled standards
3Measurement precision
If multiple samples are analyzed separately, then each sample can be processed individually, but the analysis time and resource consumption increase
Solution Approach 1:
The patent applies merging by combining multiple patient samples into a single multiplexed analysis batch. Each sample is labeled with unique isotopic tags (25OHD2-d3 for Sample 1, 25OHD3-d3 for Sample 2, etc.), allowing simultaneous analysis of multiple samples in one mass spectrometry run while maintaining the ability to individually quantify each sample's vitamin D metabolite levels
Solution Approach 2:
The patent introduces universal internal standards that can serve multiple samples simultaneously. The isotopically labeled standards (25OHD2-d3 and 25OHD3-d3) function across all samples in the multiplexed analysis, providing a universal reference system that enables high-throughput processing while maintaining individual sample precision through the unique isotopic signatures
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
Enables accurate and efficient detection and quantification of vitamin D metabolites in a single mass spectrometric assay, providing distinct ions for each sample, thereby overcoming the limitations of existing methods and allowing for precise determination of vitamin D nutritional status and bioactivity.
Implementation Method 1
subjecting the multiplex sample to an ionization source under conditions suitable to generate one or more ions detectable by mass spectrometry
Data Source
AI summary
The invention relates to the quantitative measurement of steroidal compounds by mass spectrometry. In a particular aspect, the invention relates to methods for quantitative measurement of steroidal compounds from multiple samples by mass spectrometry.