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Updated: May 29, 2026
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The Microfluidic Probe: Operation and Use for Localized Surface Processing
Published on: June 4, 2009
Liquid microjunction surface sampling probe fluid dynamics: computational and experimental analysis of coaxial
Mariam S Elnaggar1, Charlotte Barbier, Gary J Van Berkel
1Organic and Biological Mass Spectrometry Group, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Journal of the American Society for Mass Spectrometry
|September 29, 2011
Summary
Investigating liquid microjunction surface sampling probe (LMJ-SSP) dynamics revealed distinct operational modes. Retracting the inner capillary controls analyte transport, enabling new analytical applications.
Area of Science:
- Analytical Chemistry
- Surface Science
- Mass Spectrometry
Background:
- Liquid microjunction surface sampling probes (LMJ-SSPs) extract analytes from surfaces for mass spectrometry.
- The influence of solution dynamics at the probe-sample interface on LMJ-SSP performance is poorly understood.
Purpose of the Study:
- To investigate the impact of coaxial capillary retraction on flow dynamics and analyte transport in LMJ-SSPs.
- To characterize the different operational modes of the LMJ-SSP during surface sampling.
Main Methods:
- Computational fluid dynamics (CFD) simulations were employed.
- Experiments utilized a transparent LMJ-SSP for visual observation.
- Axial retraction of inner and outer capillaries was systematically varied.
Main Results:
- Probe operation transitioned between continuous sampling, an intermediate regime, and sample plug formation.
- Eddy currents at the probe tip were identified as the cause of sample plug formation.
- Inner capillary retraction was shown to control the sampling and injection modes.
Conclusions:
- The study reveals novel operational modes for LMJ-SSPs based on capillary positioning.
- These findings offer potential for enhanced analytical control and implementation of LMJ-SSPs.
- Understanding these dynamics is crucial for optimizing surface sampling efficiency and analyte transport.
