Gas Chromatography FTIR Spectroscopy Sample Cell
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Solution Overview
Problem
Conventional Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Fourier Transform Infrared Spectrometry (GC-FTIR) techniques face limitations such as MS interferences, non-linear calibrations, poor precision, limited dynamic range, and sensitivity issues due to short light pipe lengths in GC-FTIR systems, which hinder the accurate identification and quantification of molecular species, especially in high concentration samples.
Innovation Solution
A system and method that couples a time-resolved separator, like a gas chromatograph, with an optical spectroscopic analyzer using a sample cell with enhanced path length and automation features to integrate spectral signatures over time, allowing for the identification and quantification of components by averaging multiple spectra and correcting for background interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a short light pipe is used in GC-FTIR to prevent peak dilution, then peak concentration is maintained, but sensitivity is limited due to short path length
Solution Approach 1:
The patent transitions from a simple linear light pipe geometry to a multi-pass optical path configuration (such as a White cell or Herriott cell) where the light traverses the sample volume multiple times in different directions. This effectively increases the path length in three-dimensional space without proportionally increasing the physical volume, thereby improving sensitivity while avoiding peak dilution.
2Productivity
If GC-MS is used for rapid and sensitive identification of molecular species, then detection speed and sensitivity are improved, but MS interferences and spectral overlaps occur
Solution Approach 1:
The patent introduces an FTIR spectrometer as an intermediary detection method between the GC column and the final analysis. The FTIR provides complementary spectral information based on molecular vibrations rather than mass-to-charge ratios, serving as a mediator that resolves ambiguities and interferences that plague MS-based identification, particularly for structural isomers.
3Measurement precision
If GC-MS requires fully resolved peaks to prevent spectral overlaps, then identification accuracy is improved, but co-elution of components cannot be handled
Solution Approach 1:
The patent combines GC separation with FTIR spectroscopy to create a hybrid system that performs both separation and spectral identification functions. The FTIR detector provides functional group information that is independent of retention time, enabling the system to identify components even when they co-elute, thus making the system universally applicable to both resolved and co-eluting peaks.
4Reliability
If GC-MS systems operate at low pressure to prevent atmospheric leaks, then system reliability is maintained, but maintenance frequency increases and downtime increases
Solution Approach 1:
The patent employs an FTIR spectrometer that operates at atmospheric pressure, eliminating the need for vacuum systems and associated leak-prone seals and flanges. The system is self-sufficient in that it does not require frequent maintenance of pressure control mechanisms, reducing both maintenance frequency and downtime while maintaining reliable operation.
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 full spectral identification and quantification of components, including structural isomers and isotopes, with improved sensitivity and dynamic range, capable of measuring low-level compounds in the presence of high concentrations without peak splitting or interference, and requires less maintenance and calibration compared to traditional GC-MS systems.
Implementation Method 1
an optical spectroscopic analyzer using a sample cell with enhanced path length and automation features to integrate spectral signatures over time
Data Source
AI summary
Components resolved in time by a separator accumulate in a sample cell and are analyzed by electromagnetic radiation-based spectroscopic techniques. The sample cell can be configured for multiple path absorption and can be heated. The separator can be a gas chromatograph or another suitable device, for example a distillation-based separator. The method and system described herein can include other mechanical elements, controls, procedures for handling background and sample data, protocols for species identification and/or quantification, automation, computer interfaces, algorithms, software or other features.