Liquid microjunction surface sampling probe fluid dynamics: characterization and application of an analyte plug...

Area of Science:

• Analytical Chemistry
• Surface Science
• Mass Spectrometry

Background:

• Continuous flow probes are crucial for efficient sample analysis.
• Liquid microjunction surface sampling probes (LMJ-SSP) offer precise surface extraction.
• Optimizing LMJ-SSP for in-situ reactions and analyte concentration is key.

Purpose of the Study:

• To characterize the sample plug formation and injection mode of a coaxial LMJ-SSP.
• To demonstrate the probe's utility for analyte concentration, mixing, and nanoliter-scale reactions.
• To visually monitor sampling and reaction processes within the probe.

Main Methods:

• Utilized a transparent LMJ-SSP with colored analytes for visual monitoring.
• Investigated sample plug stability and injection consistency over varying hold times.
• Performed chemical reduction reactions using 2,6-dichlorophenol-indophenol and ascorbic acid.

Main Results:

• Consistent injection plug peak widths (RSD < 1.5%) were achieved for hold times up to 8 minutes.
• Integrated injection peak signals remained consistent across tested hold times.
• Demonstrated linear mass spectral response with increasing sampled analyte spots.
• Successfully sampled, concentrated, and reacted analytes within the probe's fixed volume.

Conclusions:

• The LMJ-SSP's operational mode is robust for sample handling and analysis.
• The probe enables efficient in-situ mixing and chemical reactions at the nanoliter scale.
• LMJ-SSP is a versatile tool for surface sampling, concentration, and reaction chemistry.