SPME Desorption Chamber for Undiluted Analyte Plug Transfer
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Solution Overview
Problem
Existing systems for desorbing analytes from solid phase microextraction (SPME) devices using continuous solvent flow often result in broad extraction chronograms due to non-instantaneous desorption and analyte dispersion, leading to inefficient transfer of desorbed analytes to detection instruments.
Innovation Solution
A system and method that utilize a desorption chamber with a flow-insulating fluid connector to transfer desorption solution as a substantially undiluted plug of liquid to a flow injector, minimizing mixing with solvent flowing to the injector, and including a fluid switch to isolate the solvent source during detection, ensuring high concentration and reproducibility of analyte transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous flow of solvent is used to perform desorption, then the analyte is efficiently transferred to the detection instrument, but the extraction chronograms become broad due to non-instantaneous desorption and analyte dispersion
Solution Approach 1:
The system uses periodic action by switching between solvent flow and no-flow states. The fluid switch alternates between allowing solvent to flow through the injection port (for desorption) and blocking the flow (for plug transfer), creating distinct phases that separate the desorption process from the detection process, thereby achieving both efficient transfer and narrow chronograms
Solution Approach 2:
The system performs preliminary action by completely desorbing the analyte from the SPME device into the desorption chamber before transfer to the detection instrument. The solvent flows through the chamber first, ensuring complete desorption occurs while the chamber is isolated, so that when transfer occurs, the entire analyte load is already in the chamber ready for immediate plug transfer
2Productivity
If solvent flows continuously past the extraction chamber, then analytes are transported to the mass spectrometer, but desorbed analytes may disperse in stagnant desorption solution before being sucked into the flowing solvent
Solution Approach 1:
The system segments the fluid pathway into distinct zones: the desorption chamber volume where solvent is stagnant during desorption, and the injection port volume where solvent flows continuously. The fluid switch creates a sharp boundary between these zones, allowing the analyte to desorb in a controlled stagnant environment and then be transferred as a concentrated plug to the flowing solvent system
Solution Approach 2:
The desorption chamber acts as an intermediary between the SPME device and the detection instrument. It provides a controlled environment for complete desorption using stagnant solvent, then transfers the accumulated analyte as a concentrated plug to the flowing carrier stream, eliminating the dispersion problem that would occur if solvent flowed directly past the extraction chamber
3Reliability
If the desorption chamber has a larger volume to accommodate the SPME device, then complete desorption can occur, but the void volume increases causing broader chronograms
Solution Approach 1:
The system changes the parameter of solvent flow state from continuous to periodic. During desorption, the solvent flow is stopped (zero flow rate) to create a stagnant environment in a relatively large chamber volume, ensuring complete desorption. During transfer, the solvent flow is activated to rapidly flush the analyte plug through the system, achieving both complete desorption and narrow chronograms through this parameter change
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 increases the sensitivity and reproducibility of analyte detection by maintaining high analyte concentration and reducing dilution, resulting in narrower chronogram bands and more consistent results compared to conventional methods.
Implementation Method 1
the desorption chamber and the flow injector being fluidly connected by at least a flow-insulating fluid connector
Implementation Method 2
the solvent source is fluidly connected with the flow injector at least through a pump capable of applying a pressure to the solvent to transfer the solvent to the flow injector
Implementation Method 3
a fluid switch that: (a) in a desorption position, allows the solvent to be sprayed from the flow injector while flow-insulating any desorption solution in the desorption chamber, and (b) in a detecting position, isolates the solvent source from the flow injector by turning off the solvent flow
Implementation Method 4
optionally comprising a gas source for nebulizing solvent flowing from the flow injector
Implementation Method 5
optionally comprising an agitator to vibrate an accepted SPME device
Implementation Method 6
a heater to heat the desorption chamber
Implementation Method 7
the flow-insulating fluid connector is dimensioned to reduce or avoid diffusion of desorption solution from the desorption chamber to the solvent flowing to the flow injector
Data Source
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AI summary
Disclosed herein is a system for desorbing and detecting an analyte sorbed on a solid phase microextraction (SPME) device. The system includes a desorption chamber sized to accept the SPME device while defining a void volume of less than about 50 μL; a flow injector in fluid connection with the desorption chamber, the desorption chamber and the flow injector being fluidly connected by at least a flow-insulating fluid connector; a solvent source in fluid connection with the flow injector; and a fluid switch that: in a desorption position, allows the solvent to be sprayed from the flow injector while flow-insulating any desorption solution in the desorption chamber, and in an detecting position, turns off the solvent source while maintaining the fluid connection between the flow injector and the desorption chamber, transferring the desorption solution through the flow-insulating fluid connector to the flow injector as a substantially undiluted plug of liquid.