Pulsed capillary introduction applied to a miniature mass spectrometer for efficient liquid analysis.

Area of Science:

• Analytical Chemistry
• Mass Spectrometry Instrumentation

Background:

• Direct liquid analysis using mass spectrometry (MS) via capillary sampling faces challenges with low transfer rates, impacting sensitivity and response time.
• A novel pulsed capillary introduction (PCI) method was developed to overcome these limitations in capillary-based MS analysis.

Purpose of the Study:

• To introduce and characterize a pulsed capillary introduction (PCI) method for direct liquid analysis using mass spectrometry.
• To evaluate the impact of PCI on analytical sensitivity, response time, and sample consumption compared to continuous methods.

Main Methods:

• Utilized a miniature quadrupole mass spectrometer for experiments.
• Implemented pulsed injection by controlling capillary inlet contact with liquid samples using a motor platform.
• Optimized pulsed sampling parameters through characterization and dynamic studies of liquid transfer in capillaries.

Main Results:

• PCI reduced MS analysis response time from over 30 seconds to a few seconds.
• Achieved enhanced ion signals and an eightfold lower limit of detection (LOD) for toluene compared to continuous capillary introduction (CCI).
• Demonstrated minimal sample consumption (nanoliter range) and femtogram-level absolute analyte detection.

Conclusions:

• The PCI method successfully improves sampling efficiency for direct liquid MS analysis without increasing vacuum load.
• Miniature MS instruments equipped with capillary inlets can offer flexible operation modes for diverse applications.