Peak Extraction Method for Chromatogram Signal Analysis
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Solution Overview
Problem
Existing peak extraction methods from chromatograms and spectra enhance noise along with true peaks after second-derivative analysis, making it difficult to detect low S/N ratio peaks due to enhanced noise from steep waveform noise.
Innovation Solution
A method that involves acquiring a second derivative waveform, extracting provisional peaks based on maximum and minimum values, determining peak width using a model peak function, computing theoretical peak height, calculating a noise index value, and extracting true peaks based on a computed S/N ratio that meets a preset threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If second-derivative signal analysis is performed to remove baseline drift effects, then baseline drift is reduced, but noise is enhanced along with true peaks
Solution Approach 1:
The patent applies parameter changes by transforming the signal from the time domain to the frequency domain through Fourier transformation. This allows selective filtering of noise components based on their frequency characteristics while preserving the peak signals, thereby reducing noise enhancement while maintaining baseline drift correction capabilities
Solution Approach 2:
The patent introduces an intermediary approach by using correlation processing between the measured waveform and a reference waveform. This intermediary method allows the system to distinguish between true peak signals and noise by comparing their correlation characteristics, thereby reducing noise enhancement while maintaining peak detection accuracy
2Difficulty of detecting and measuring
If second derivative is applied to enhance local signal intensity changes, then peak detection capability is improved, but low S/N ratio peaks become undetectable due to enhanced noise
Solution Approach 1:
The patent transforms the signal to the frequency domain and applies selective filtering to change the parameter of signal-to-noise ratio. By filtering out high-frequency noise components while preserving peak-related frequency components, the system maintains peak detection capability while making low S/N ratio peaks detectable
Solution Approach 2:
The patent uses correlation processing that provides feedback mechanisms to distinguish true peaks from noise. By comparing the measured waveform with reference waveforms and analyzing correlation coefficients, the system can identify low S/N ratio peaks that would otherwise be lost in enhanced noise
Data Source
AI summary
A peak extraction method for extracting a true peak from a measured waveform, including acquiring a second derivative waveform; extracting a provisional peak on the basis of a maximum value and/or a minimum value of the second derivative waveform; determining the peak width of the provisional peak on the basis of a model peak function; computing, on the basis of the model peak function, a theoretical value for the height of the provisional peak using two points corresponding to the two ends of the peak width; computing, based on the second derivative waveform, an index value for a variation in the noise on the measured waveform; and computing an S/N ratio, which is a ratio of the peak height theoretical value and the index value, and extracting the provisional peak that is equal to or greater than a preset value as the true peak.