On-line solid-phase preconcentration for sensitivity enhancement in capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Biochemistry
• Separation Science

Background:

• Capillary electrophoresis (CE) offers high resolution for biological sample analysis due to minimal sample injection volumes (nanoliters).
• However, small injection volumes lead to detection sensitivity limitations, especially for low-concentration analytes in complex biological matrices.

Purpose of the Study:

• To review the application of on-line preconcentration techniques to overcome detection sensitivity limitations in CE.
• To highlight the benefits of solid-phase extraction for sample enrichment in CE analysis of biological samples.

Main Methods:

• On-line preconcentration using reversed-phase material (e.g., C18 particles or membrane) integrated into the CE capillary inlet.
• Solid-phase extraction (SPE) for sample enrichment, followed by elution of adsorbed analytes directly into the CE capillary.
• Coupling CE with mass spectrometry (CE-MS) for enhanced detection.

Main Results:

• On-line preconcentration allows injection of larger sample volumes (1-100 µL), improving effective concentration limits of detection by 100-1000 fold.
• Detection of analytes at concentrations as low as 20 amol/µL in complex mixtures has been achieved.
• Facilitates direct analysis of biological samples, reducing the need for extensive off-line pretreatment.

Conclusions:

• On-line preconcentration is a powerful strategy to enhance CE sensitivity for biological sample analysis.
• This approach significantly improves detection limits, enabling the analysis of trace-level analytes.
• It offers a simplified workflow for analyzing complex biological samples without rigorous sample preparation.