Concentration and separation of hypoglycemic drugs using solid-phase extraction-capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Conventional capillary electrophoresis (CE) techniques have limitations in detecting very dilute analytes.
• Hypoglycemic drugs, particularly sulfonylureas, require sensitive analytical methods for monitoring in biological samples like urine.

Purpose of the Study:

• To develop and validate a solid-phase extraction-capillary electrophoresis (SPE-CE) method for direct analysis of hypoglycemic drugs in urine.
• To improve the sensitivity and selectivity of drug detection compared to standard CE methods.

Main Methods:

• Development of an on-line solid-phase extraction (SPE) coupled with capillary electrophoresis (CE) for sample preconcentration.
• Optimization of non-micellar electrokinetic chromatography (MEKC) separation conditions using a borate/phosphate buffer system.
• Analysis of six sulfonylurea drug standards and assessment of linearity and sensitivity.

Main Results:

• Effective extraction and concentration of six sulfonylurea drugs from urine samples.
• Achieved detection limits approximately 5 ng/ml, significantly lower than conventional CE.
• Demonstrated improved resolution of closely related drugs (glipizide and glyburide) compared to standard capillary zone electrophoresis (CZE).
• Established a linear sample loading range from 0.12 to 1.9 microliters.

Conclusions:

• SPE-CE offers a significant increase in sensitivity for the detection of hypoglycemic drugs in urine.
• The SPE process can alter chromatographic selectivity, enabling separation of compounds unresolved by standard CE.
• This SPE-CE method provides a robust and sensitive approach for direct analysis of target drugs in complex matrices.