Repetitive injection field-amplified sample stacking for cationic compounds determination.

Area of Science:

• Analytical Chemistry
• Biochemistry

Background:

• Capillary electrophoresis (CE) often requires pre-concentration techniques to enhance analyte detection.
• Field-amplified sample stacking (FASS) is a powerful pre-concentration method for CE.

Purpose of the Study:

• To develop and optimize a FASS technique for sensitive determination of psychiatric drugs.
• To apply the developed method for the analysis of psychiatric drugs in human urine samples.

Main Methods:

• Optimization of background electrolyte (BGE) composition and sample matrix.
• Utilizing repetitive sample injection with counter-pressure for effective sample stacking.
• Applying voltage and counter-pressure for a focusing step post-injection.

Main Results:

• Achieved a 4-fold effective injection volume.
• Optimized conditions involved 80 mM H3PO4 as BGE and 0.5 mM H3PO4 with 30% methanol in the sample matrix.
• Obtained low detection limits for six psychiatric drugs (2.23-6.21 ng/mL) in human urine after liquid-liquid extraction.

Conclusions:

• The developed FASS technique significantly enhances sensitivity for psychiatric drug analysis.
• The method is robust and applicable for the determination of target drugs in complex biological matrices like urine.