Potential of Capillary Electrophoresis (CE) and Chip-CE with Dual Detection (Capacitively-Coupled Contactless Conductivity Detection (C⁴D) and Fluorescence Detection) for Monitoring of Nicotine and Cotinine Derivatization

Abstract

Capillary electrophoresis (CE) coupled with capacitively-coupled contactless conductivity (C⁴D) and fluorescence (FD) detectors and chip-CE for monitoring of nicotine and cotinine derivatization was demonstrated. Separation of the substrates and intermediates could be achieved by CE-C⁴D in 7 min (R_s > 2.7) using 45 mM acetic acid (pH 3.0) and this system was applied to detect the intermediate formation. Final fluorescent products could be analyzed by micellar electrokinetic chromatography (MEKC-FD) in 5 mM borate buffer (pH 9.0) containing 10 mM sodium dodecylsulfate (SDS) (%RSD < 3.00%). Transferring of MEKC-FD to chip-CE allowed for shorter analysis time (2.5 min) and decreased sample consumption. The chip-CE-FD shows good detection and quantitation limits (< 7.5 μM) and precision (%RSD < 2.81%) and was employed to determine nicotine and cotinine in artificial urine. This work reveals the potential of CE and chip-CE with dual detectors as simultaneous, convenient and rapid methods for monitoring pyridine derivatization.