MIR Flow Cell Analyzer for Liquid Chromatography Trace Detection
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Solution Overview
Problem
Current Fourier transform infrared (FTIR) spectrometers face challenges in characterizing liquid samples due to strong background absorptions and limited path lengths, making it difficult to detect trace fractions and distorting spectral signatures, especially in liquid chromatography systems where time resolution is critical.
Innovation Solution
A liquid chromatography analyzer system incorporating multiple mid-infrared (MIR) analyzers in series, each with a flow cell, laser source, and detector, capable of rapidly modulating wavelengths and combining data to achieve high sensitivity and temporal resolution for trace fraction analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If FTIR spectrometers use broadband globar incandescent source for MIR characterization of liquid samples, then the optical powers per wavelength are quite low, but the path lengths through liquids must be kept small to avoid attenuation of probe light to unacceptably low values
Solution Approach 1:
The patent changes the fundamental parameter of the light source from broadband globar incandescent to quantum cascade laser (QCL), which provides high optical power at specific mid-infrared wavelengths. This parameter change enables sufficient signal intensity even through longer path lengths, resolving the contradiction between needing high optical power and maintaining acceptable path length for trace fraction detection.
2Ease of operation
If FTIR spectrometers use ATR interfaces to handle liquid samples, then the interfaces are easier to use, but the path lengths become smaller and spectral signatures are distorted due to combined effect of absorption and changing refractive index
Solution Approach 1:
The patent extracts the light source and detection system from the traditional ATR interface configuration. By using QCL-based direct absorption spectroscopy without ATR crystals, the system eliminates the refractive index distortion problem while maintaining ease of liquid sample analysis through simple flow cells or cuvettes.
3Measurement precision
If FTIR instruments are used for liquid chromatography fraction analysis, then the system can characterize liquid samples, but the time resolution is insufficient to resolve fractions that flow through in tens of milliseconds to a few seconds
Solution Approach 1:
The patent replaces the mechanical moving-mirror scanning system of traditional FTIR with a quantum cascade laser that directly emits tunable mid-infrared light. This substitution enables rapid wavelength modulation and fast spectral acquisition, achieving the necessary time resolution to capture transient chromatographic fractions while maintaining characterization accuracy.
4Quantity of substance
If conventional FTIR is used for trace fraction detection, then the system can analyze liquid samples, but the sensitivity is insufficient to detect trace fractions (less than one part per thousand)
Solution Approach 1:
The patent changes the detection parameter by using quantum cascade lasers that provide high optical power at specific mid-infrared wavelengths where trace compounds have strong absorption features. Combined with rapid scanning capabilities, this enables detection of trace fractions at concentrations below one part per thousand with high measurement precision.
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
The system effectively characterizes liquid samples by preserving concentration, providing sufficient signal-to-noise for trace fraction identification and maintaining temporal resolution, enabling accurate analysis of sample fractions in liquid chromatography systems.
Implementation Method 1
a first MIR laser source that directs a first MIR beam modulated in a first MIR wavelength range at the first sample fraction
Implementation Method 2
direct absorption to spectrally analyze the different sample fractions
Data Source
AI summary
A chromatography analyzer system (10) for analyzing a sample (12) includes a MIR analyzer (34) for spectrally analyzing a sample fraction (12A) while the sample fraction (12A) is flowing in the MIR analyzer (34). The MIR analyzer (34) includes (i) a MIR flow cell (35C) that receives the flowing sample fraction (12A), (ii) a MIR laser source (35A) that directs a MIR beam (35B) in a MIR wavelength range at the sample fraction (12A) in the MIR flow cell (35C), and (iii) a MIR detector (35D) that receives light from the sample fraction (12A) in the MIR flow cell (35C) and generates MIR data of the sample fraction (12A) for a portion of the MIR wavelength range.