Waveform Baseline Determination for Peak Clusters
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Solution Overview
Problem
Existing methods for determining baselines in waveforms with closely spaced peaks, such as in chromatography and spectrometry, often result in errors due to baseline drift and intersection of baselines, especially when multiple peaks or positive and negative peaks are close together, leading to inaccurate peak area calculations.
Innovation Solution
A waveform data processing device and program that determine a baseline for a peak cluster by finding the shortest straight line or line segments connecting the starting and ending points of the cluster, ensuring the baseline passes below positive peaks, above negative peaks, and remains unaffected by mixed peak sections, using a 'rubber band model' to minimize intersection points and correct for non-peak sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a baseline is determined for each peak by connecting starting and ending points, then the baseline determination is simple, but the baseline becomes higher than actual when peaks are close together, causing large errors in peak area measurements
Solution Approach 1:
The patent merges multiple individual peak baselines into a single common baseline for the entire peak cluster. Instead of determining separate baselines for each peak (which causes intersection and overestimation), the invention treats the cluster as one unit and determines a unified baseline that passes below all peaks, thereby eliminating baseline intersection errors and improving peak area measurement accuracy.
Solution Approach 2:
The patent introduces a new dimension to baseline determination by implementing an iterative optimization process. The baseline is initially determined and then repeatedly adjusted by checking for intersections with peaks and modifying the baseline equation parameters (slope and intercept) until no intersections occur. This iterative dimensional adjustment ensures the baseline remains below all peaks while maintaining mathematical simplicity.
2Measurement precision
If a common baseline is determined for a peak cluster, then baseline intersection errors are reduced, but the baseline may still be inaccurate when positive and negative peaks are mixed together
Solution Approach 1:
The patent applies local quality by treating positive and negative peaks differently within the same peak cluster. The baseline determination process specifically checks for intersections with both positive peaks (which would indicate the baseline is too high) and negative peaks (which would indicate the baseline is too low). This localized adjustment ensures the baseline adapts to the specific characteristics of each peak type while maintaining a unified baseline for the entire cluster.
Solution Approach 2:
The patent implements a feedback mechanism where the determined baseline is continuously evaluated against all peaks in the cluster. The process checks whether the baseline intersects with any peaks and uses this feedback information to iteratively adjust the baseline equation parameters. This feedback loop ensures the baseline automatically adapts to mixed peak types by learning from intersection patterns and making corrective adjustments until the baseline properly separates all peaks.
3Ease of operation
If baseline determination is performed for each peak individually, then processing is straightforward, but time consumption increases when multiple peaks require separate baseline calculations
Solution Approach 1:
The patent merges the baseline determination process for multiple peaks into a single unified calculation. Instead of performing separate baseline determinations for each peak (which would require multiple independent calculations), the invention determines one common baseline for the entire peak cluster using a single set of equations. This merging approach significantly reduces processing time while maintaining ease of operation, as the unified baseline determination requires only one iterative optimization process rather than multiple separate ones.
Data Source
AI summary
A waveform data processing device 30 capable of accessing a storage device 40 for storing data on an observed waveform such as a chromatogram, information on a starting point and an ending point of a peak cluster consisting of a plurality of peaks close one another present on the observed waveform, and information on a position of each peak included in the peak cluster and a positive/negative direction of the each peak, includes baseline determination means for determining, based on the data and the information stored in the storage device 40, a shortest straight line or shortest line segments from the starting point of the peak cluster as a beginning point to the ending point of the peak cluster as a finishing point satisfying all following conditions, and determining the straight line or the line segments to be a baseline of the peak cluster: (1) in a section where positive peaks are contiguous, a baseline passes below the observed waveform, becoming a straight line or line segments convex downward; (2) in a section where negative peaks are contiguous, a baseline passes above the observed waveform, becoming a straight line or line segments convex upward; and (3) in a section where positive and negative peaks are contiguous, the shape of a baseline is not influenced by the observed waveform.