FTIR Interference Spectra Using a Switched Reaction Reactor
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Solution Overview
Problem
Current Fourier transform infrared (FTIR) spectrometers face challenges in accurately measuring compounds at very low levels due to spectral interferences, particularly when the analyte of interest is many orders of magnitude smaller than interfering species, leading to biases in analysis.
Innovation Solution
A gas analysis system that includes a switched reaction device and a controller to selectively provide a sample stream or a reacted sample stream to a spectrometer, allowing for the creation of interference spectra without changing the sample matrix, which can be used for accurate analysis of analytes like ethylene oxide at low parts-per-billion or parts-per-trillion levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FTIR spectrometry is used to measure compounds at very low levels, then the measurement capability is limited by spectral interferences from interfering species, but using a switched reaction device with selective removal adds system complexity
Solution Approach 1:
The patent extracts the interfering species from the sample stream by passing it through a reaction device where the interferent is selectively removed or converted. This allows the spectrometer to measure the analyte without interference, effectively taking out the problematic component before measurement.
Solution Approach 2:
The reaction device acts as an intermediary between the sample and the spectrometer. It selectively modifies the interfering species while leaving the analyte unchanged, serving as a mediator that prepares the sample for accurate measurement by removing only the harmful interference.
2Measurement precision
If pure component calibration spectra are used for interference correction, then the calibration is based on ideal conditions, but the residual spectrum remains 1-2% of sample intensity due to matrix differences
Solution Approach 1:
The patent performs preliminary action by collecting the interference spectrum from the actual sample matrix under the same measurement conditions before analyzing the analyte. This preliminary measurement captures the exact interference present in the specific sample, allowing for more accurate subtraction and reducing residual errors.
Solution Approach 2:
The approach changes the parameter of spectral matching from using idealized pure component spectra to using actual measured interference spectra from the specific sample matrix. This parameter change adapts the calibration to real-world conditions, significantly improving match accuracy.
3Measurement precision
If the analyte concentration is 100's to 100,000's times smaller than the interfering matrix, then the analyte signal is buried in the interference, but conventional background subtraction cannot achieve sufficient accuracy
Solution Approach 1:
The reaction device selectively removes or converts the interfering species from the sample stream, extracting the harmful interference component. This allows the trace analyte signal to be measured without being overwhelmed by the interfering matrix, enabling detection at 100's to 100,000's times lower concentrations.
Solution Approach 2:
The method converts the harmful spectral interference into a beneficial measurement opportunity. By selectively removing the interferent, the previously problematic overlapping signals become clean measurements of the trace analyte, turning the interference problem into a solution.
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 enables precise interference spectrum determination and removal of interfering species, allowing for direct measurement of analytes at extremely low concentrations, improving the accuracy of FTIR analysis and extending its applicability to reactive chemical agents and complex gas mixtures.
Implementation Method 1
A switched reaction device, such as a heated oxidation catalyst, a hot furnace reactor, UV illumination or photo-ionization, chemical reaction with reagent or other of a switched reaction device
Implementation Method 2
Fourier transform infrared (FTIR) spectrometer for low level gas detection of chemicals
Data Source
AI summary
A gas analysis system and method with a spectrometer, such as a Fourier transform infrared spectrometer, utilizing a reactor, such as a catalytic reactor, for providing reference spectra.