Direct sampling and analysis from solid-phase extraction cards using an automated liquid extraction surface analysis
Matthew J Walworth1, Mariam S ElNaggar, Joseph J Stankovich
1Oak Ridge National Laboratory, Oak Ridge, TN 37831-6131, USA.
Rapid Communications in Mass Spectrometry : RCM
|July 28, 2011
Summary
Liquid extraction surface analysis (LESA) was adapted for 96-well solid-phase extraction (SPE) cards using nanoelectrospray ionization (nanoESI). This method enhances signal and enables sensitive analysis of complex mixtures, including herbicides.
Area of Science:
- Analytical Chemistry
- Mass Spectrometry
- Separation Science
Background:
- Direct liquid extraction surface sampling has evolved with new probe technologies.
- Liquid extraction surface analysis (LESA) is now integrated into chip-based nanoelectrospray ionization (nanoESI) systems.
Purpose of the Study:
- To apply LESA mode to 96-well solid-phase extraction (SPE) cards for enhanced sample analysis.
- To optimize extraction conditions and evaluate performance metrics for targeted compounds.
- To demonstrate the system's capability for analyzing complex mixtures and identifying compounds in challenging matrices.
Main Methods:
- Utilized a commercial chip-based infusion nanoESI system in LESA mode.
- Employed custom 96-well SPE cards with monolithic hydrophobic stationary phases (1-2 mm diameter).
- Analyzed aqueous mixtures using hybrid triple quadrupole/linear ion trap or linear ion trap mass spectrometry.
Main Results:
- Optimized extraction solvent composition, volume, and dwell times for targeted compounds.
- Achieved significant signal enhancement (10x) and purification of angiotensin II from salt solutions.
- Demonstrated linearity and reproducibility for propranolol calibration using a deuterated internal standard.
- Successfully analyzed multicomponent herbicide mixtures at ppb levels using MS(3) for identification, overcoming isobaric interferences.
Conclusions:
- The LESA mode on commercial nanoESI systems is effective for analyzing samples on 96-well SPE cards.
- The method offers improved sensitivity, sample cleanup, and compound identification capabilities.
- This approach is suitable for analyzing complex mixtures and trace analytes in various applications.
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