Development and Validation of Capillary Electrophoresis Method for Simultaneous Determination of Six Pharmaceuticals in Different Food Samples Combining On-line and Off-line Sample Enrichment Techniques

A rapid and highly sensitive capillary electrophoresis method was developed combining on-line and off-line sample enrichment techniques that are capable to determine six widely used pharmaceuticals, viz. amoxicillin, carbamazepine, diclofenac, indomethacin, ibuprofen, and paracetamol from various food samples. A new sample preconcentration technique, i.e., in situ aggregated microextraction, was utilized to extract the analytes from various food samples. The process was carried out by the formation of aggregate phase in situ in the aqueous sample by ion association between oppositely charged surfactants, viz. Tiron® and cetyltrimethylammonium bromide. The separation and quantification of analytes were carried out in micellar electrokinetic chromatography mode at −20 kV. In short, the uncoated fused silica capillaries were filled with 80 mM phosphate buffer solution (pH 6.0) to act as leading electrolyte, and the samples were dissolved in 100 mM borate buffer and injected by electrokinetic mode applying −10 kV for 600 s. The method showed good linearity in between 0.06 and 50 μg/L for all six pharmaceuticals. Good repeatability and recoveries were obtained for all analytes in the range of 94.45–106.32% using optimized experimental conditions. The limit of detection ranged from 0.02 to 0.08 μg/L, and the limit of quantification ranged from 0.06 to 0.25 μg/L for six pharmaceuticals. The sensitivity of the developed micellar electrokinetic chromatography method was increased about 2500-folds compared to conventional capillary zone electrophoresis method. Finally, the developed analytical procedure was applied successfully for the detection of selected pharmaceuticals in fruits, urine, and river water samples.