At-line solid-phase extraction for capillary electrophoresis: application to negatively charged solutes

Area of Science:

• Analytical Chemistry
• Biochemistry

Background:

• Capillary electrophoresis (CE) is crucial for analyzing complex biological samples.
• Effective sample pretreatment is essential for CE analysis.
• Solid-phase extraction (SPE) is a common sample preparation technique.

Purpose of the Study:

• To investigate the applicability of solid-phase extraction (SPE) coupled at-line with capillary electrophoresis (CE).
• To develop an automated method for sample handling and analysis.
• To assess the performance and robustness of the integrated SPE-CE system.

Main Methods:

• Utilized a laboratory-made interface for at-line coupling of SPE with CE.
• Employed fresh, disposable SPE cartridges for each sample to prevent carry-over.
• Performed sample handling in parallel with previous analyses to increase throughput.
• Analyzed negatively charged test compounds, including non-steroid anti-inflammatory drugs, in serum and urine.

Main Results:

• Achieved linearity over at least two concentration decades.
• Reported detection limits around 40 µg/l for the analytes.
• Demonstrated system robustness with a single capillary used for approximately 900 samples over 1 year without blocking.
• Successfully implemented overnight runs, indicating high system stability.

Conclusions:

• The at-line SPE-CE system provides an efficient and robust method for analyzing complex biological samples.
• The automated approach significantly improves sample throughput.
• The system is suitable for routine analysis of negatively charged compounds in biological matrices like serum and urine.