Stacking in electrophoresis by electroosmotic flow-assisted admicelle to solvent microextraction

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Capillary electrophoresis (CE) requires efficient sample preconcentration for trace analysis.
• Existing methods often involve complex procedures or external equipment.

Purpose of the Study:

• To develop and optimize an in-line sample concentration technique for capillary electrophoresis.
• To improve the sensitivity and efficiency of analyte detection using admicelle to solvent microextraction.

Main Methods:

• Admicelle to solvent microextraction was employed, utilizing cetyltrimethylammonium bromide admicelles on a capillary surface.
• Analyte trapping in admicelles followed by solvent plug injection to collapse admicelles and focus analytes.
• Optimization of solvent composition (acetonitrile/sodium tetraborate), injection times, and solvent-to-sample ratios.

Main Results:

• Achieved 132-176-fold enhancement in UV detection sensitivity for model anions.
• Established optimal conditions: 30% acetonitrile in 24 mM sodium tetraborate (pH 9.2), 320s sample injection, 1:2 solvent-to-sample ratio.
• Demonstrated good repeatability (1.9-3.9% intra-day, 2.8-4.9% inter-day) and linearity (R²=0.992).
• Successfully applied to fortified water samples with low %RSD (0.5-3.6%) and no matrix interferences.

Conclusions:

• Admicelle to solvent microextraction is an effective in-line preconcentration technique for CE.
• The method offers significant sensitivity enhancement and reliable performance for trace analysis in complex matrices like water.