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Pseudophase microextraction for in-line sample concentration in micellar electrokinetic chromatography
Raymond B Yu1, Joselito P Quirino1
1Australian Centre for Research on Separation Science (ACROSS), School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
Analytica Chimica Acta
|November 24, 2021
Summary
Pseudophase microextraction (PPME) is a novel pressure-driven sample concentration technique for micellar electrokinetic chromatography (MEKC). This method significantly enhances analyte detection limits, offering substantial improvements over traditional methods.
Area of Science:
- Analytical Chemistry
- Separation Science
- Capillary Electrophoresis
Background:
- Micellar electrokinetic chromatography (MEKC) is a powerful separation technique.
- Existing electric-field driven stacking techniques in MEKC have limitations.
- There is a need for simple, efficient in-line sample concentration methods.
Purpose of the Study:
- To introduce and characterize Pseudophase Microextraction (PPME) as an in-line sample concentration technique for MEKC.
- To evaluate the performance of PPME-MEKC for the analysis of specific analytes.
- To compare PPME with existing stacking techniques like sweeping.
Main Methods:
- PPME involves loading the capillary with sample in a dilute cetyltrimethylammonium bromide (CTAB) solution, forming a stationary pseudophase.
- Analytes are eluted using the MEKC background solution (BGS) and concentrated at its front.
- The concentrated band is then subjected to MEKC separation.
Main Results:
- PPME achieved significant peak height improvements (up to 403-2968x) for target analytes compared to typical injection.
- PPME demonstrated superior performance (up to 23-59x better) compared to sweeping under similar MEKC conditions.
- Linear ranges (1-160 ng/mL), low LOQs (1-2.5 ng/mL), and good repeatability (≤7% inter-day RSD) were achieved.
- Successful detection of analytes in real water samples with high recovery rates (84-108%) was demonstrated.
Conclusions:
- PPME is a highly effective, pressure-driven in-line sample concentration technique for MEKC.
- The method offers substantial sensitivity enhancements and is applicable to real-world sample analysis.
- The PPME concept holds potential for broader applications in capillary electrophoresis and microscale separations.
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