Spray Drying Liquid Chromatography Effluent for FTIR Analysis
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Solution Overview
Problem
Existing techniques for interfacing liquid chromatography (LC) with Fourier transform infrared (FTIR) spectroscopy face challenges due to the infrared absorption of mobile phases used in LC, leading to limited success in identifying components of chemical mixtures, especially for less volatile and more polar compounds, as current methods either compromise on sensitivity or require complex solvent elimination processes.
Innovation Solution
A novel spray drier system that converts a flowing liquid stream into a high-speed aerosol jet, using film boiling to rapidly evaporate solvents, followed by solvent vapor removal through condensation, allowing for the deposition of concentrated, structurally intact solutes on a surface for infrared analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If liquid chromatography is interfaced with FTIR spectroscopy using conventional flow cells, then structural information can be obtained, but the infrared absorption of mobile phases limits the path length and compromises measurement accuracy
Solution Approach 1:
The invention extracts and removes the mobile phase from the liquid stream before IR analysis. The spray drier system evaporates the mobile phase completely, leaving only the analyte particles for IR spectroscopy, thereby eliminating the harmful infrared absorption of the mobile phase
Solution Approach 2:
The mobile phase removal is performed preliminarily before the IR spectroscopy measurement. The spray drier pre-treats the liquid chromatography effluent by evaporating the mobile phase and concentrating the analyte, so that when the sample reaches the IR detector, no mobile phase interference remains
2Measurement precision
If the mobile phase is eliminated prior to deposition on substrate, then IR spectra can be obtained, but the complexity of the interface system increases
Solution Approach 1:
The invention merges multiple functions into a single integrated spray drier device: nebulization of the liquid stream, heating for evaporation, and particle deposition on the substrate all occur in one compact unit, reducing overall system complexity while achieving mobile phase removal
Solution Approach 2:
The spray drier utilizes phase transition of the mobile phase from liquid to vapor through rapid heating and evaporation. This natural phase change process efficiently separates the mobile phase from the analyte without requiring complex mechanical separation systems
3Quantity of substance
If conventional solvent removal methods are used, then some solvent elimination is achieved, but temporal separation of solutes is lost and structural integrity is compromised
Solution Approach 1:
The invention replaces mechanical solvent removal methods with a thermal field-based spray drier system. The controlled heating and rapid evaporation process removes solvent while maintaining solute integrity through brief exposure times and uniform heating
Solution Approach 2:
The spray drier maintains continuous operation throughout the solvent removal process, ensuring that solutes remain in a consistent state from nebulization through evaporation to deposition. This continuous action prevents temporal separation and maintains structural integrity
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 effectively desolvates liquid streams while preserving the chemical and structural integrity of low-volatility components, enabling accurate infrared spectrographic analysis of chromatographic effluents, overcoming previous limitations in solvent elimination and sensitivity.
Implementation Method 1
The cavity surface is heated to cause the droplets to film boil. The polyimid or silicone-covered thin metal film heater and/or electric cartridge heater are powered from a temperature controller with temperatures being sensed by thermocouple(s).
Implementation Method 2
solvent vapor removal through condensation
Data Source
AI summary
Methods and apparatus for desolvating flowing liquid streams while retaining temporal resolution of dissolved substrates are disclosed. A novel small-scale self-regulating spray dryer preserves temporal resolution while desolvating a liquid chromatography eluent stream and depositing the solute onto an optical surface for infrared spectrographic analysis. The liquid eluent is pumped through a heated nebulizer to create a high-speed jet of solute containing liquid and solvent vapor. This jet is directed circumferentially inside a hot cylindrical cavity. Centrifugal force causes the larger liquid droplets to travel along the outer diameter of the cavity. The cavity surface is heated to cause the droplets to film boil. Film boiling reduces droplet contact with the cavity surface thereby retaining the solute in the droplets. The solute temperature is limited by controlling the pressure into which the solvent evaporates from the droplets. When the droplets are sufficiently small, Stokes drag from the exiting solvent vapor carries the droplets out through the center of the cylindrical cavity. After exiting, the superheated solvent vapor further dries the droplets. Solvent vapor is removed by condensation onto a cooled surface. A freezing point reducing agent may be added to improve removal of solvent condensate. Stokes drag from a non-condensable gas maintains the dried droplets in suspension. This suspension travels through an orifice that focuses the impaction of the dried droplets onto the optical surface for infrared analysis. The deposition surface is in an evacuated chamber and is temperature controlled to freeze liquid solutes yet allowing sublimation of residual solvent.