Determination of arecoline in areca nut based on field amplification in capillary electrophoresis coupled with electrochemiluminescence detection.

A sensitive capillary electrophoresis-electrochemiluminescence (CE-ECL) assay with an ionic liquid (IL) was developed for the determination of arecoline in areca nut. The IL, 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF(4) ), was an effective additive improved not only the separation selectivity but also the detection sensitivity of the analyte. BMImBF(4) in the separation electrolyte made the resistance of the separation buffer much lower than that of the sample solution, which resulted in an enhanced field amplified electrokinetic injection CE. ECL intensity of arecoline is about two times higher than that of the analyte with phosphate-IL buffer system. Resolution between arecoline and other unknown compounds in real samples was improved. Under the optimized conditions (ECL detection at 1.2 V, 16 kV separation voltage, 20 mmol/L phosphate with 10 mmol/L BMImBF(4) buffer at pH 7.50, 5 mmol/L Ru(bpy)(3)(2+) and 50 mmol/L phosphate buffer in the detection reservoir), a detection limit of 5 × 10(-9) mol/L for arecoline was obtained. Relative standard deviations of the ECL intensity and the migration time were 4.51% and 0.72% for arecoline. This method was successfully applied to determination of the amount of arecoline in areca nut within 450 s.

Sensitive determination of verticine and verticinone in Bulbus Fritillariae by ionic liquid assisted capillary electrophoresis-electrochemiluminescence system.

CE/Ru(bpy)(3)(2+) electrochemiluminescence (ECL) system with the assistance of ionic liquids (ILs) was successfully established for sensitive determination of verticine and verticinone in Bulbus Fritillariae for the first time. Migration behavior of alkaloid largely relies on the hydrogen bonding interactions between alkyl imidazolium cations in ILs and the alkaloids. Running buffer containing 40 mmol/L 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF(4)) IL-8 mmol/L phosphate resulted in significant changes in separation selectivity for alkaloids with similar structures. The highest sensitivity of the detection was obtained by maintaining the detection potential at 1.2V. Under the optimized conditions, relative standard derivations of the ECL intensity and the migration time were 3.27 and 2.84% for verticine and 4.42 and 1.69% for verticinone, respectively. The standard curves were linear between 1x10(-8) and 1x10(-6) mol/L for verticine and between 5x10(-8) and 1x10(-6) mol/L for verticinone, respectively. Detection limits of 1.25x10(-10) mol/L for verticine and 1x10(-10) mol/L for verticinone were obtained (S/N=3). Developed method was successfully applied to determine the amounts of alkaloids in Bulbus Fritillariae.