Dynamic Mass Defect Filtering for Peptide Ion Identification

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Solution Overview

Problem

Current mass spectrometry methods use fixed mass defect filtering windows that do not scale with ion mass and lack statistical confidence measures, making them suboptimal for filtering data across a wide mass range and failing to effectively differentiate peptide ions from non-peptide ions.

Innovation Solution

A statistical model is developed to calculate the mass defect distribution of peptides, allowing for a dynamically scaled mass defect window based on the mass of the compound, which includes a confidence measure to filter out non-peptide ions while retaining most peptide ions, using equations to estimate the average mass defect and standard deviation for filtering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a fixed mass defect filtering window is used, then the filtering method is simple to implement, but the filtering accuracy deteriorates across wide mass ranges

Engineering Contradiction:
Improveease of implementationVSAvoidfiltering accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent transforms the static fixed mass defect window into a dynamic adaptive window that automatically adjusts its parameters based on the ion mass being analyzed. The window width and position are calculated using statistical models (mean and standard deviation of mass defect distributions) that vary with mass, allowing the filtering method to maintain high accuracy across the entire mass range while remaining computationally efficient.

Inventive Principle:
Principle #15Dynamics

2Productivity

If a fixed mass defect filtering window is used, then the method is computationally efficient, but the ability to differentiate peptide ions from non-peptide ions deteriorates

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidion differentiation capability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the parameters of the filtering window (width, position, shape) as a function of ion mass rather than using fixed parameters. By modeling the mass defect distribution statistics (mean and standard deviation) and using these to define the window parameters, the method achieves both computational efficiency through statistical formulas and high reliability in ion differentiation by adapting to the actual distribution characteristics at each mass point.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If a mass-independent filtering window is used, then the filtering process is straightforward, but the statistical confidence performance deteriorates

Engineering Contradiction:
Improvefiltering simplicityVSAvoidstatistical confidence
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic filtering approach where the window parameters are continuously adjusted based on the ion mass and the statistical properties of the mass defect distribution at that mass. This allows the filtering process to maintain statistical confidence by adapting to the actual data characteristics while preserving relative simplicity through automated parameter calculation based on established statistical models.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS7634364B2Methods and systems for mass defect filtering of mass spectrometry data
Publication Date: 2009.12.15 MDS INC
  • US7634364B2 patent drawing
  • US7634364B2 patent drawing
  • US7634364B2 patent drawing

AI summary

The present teachings relate to a method of filtering mass spectrometer data using a variable filter window. The width of the window can depend on the mass itself and the mass defects for a family of compounds. The teachings can be used with a plurality of compounds including but not limited to peptides and can be utilized on a brood range of mass spectrometers.