Off-line hyphenation of molecularly imprinted magnetic nanoparticle-based extraction with large volume sample stacking capillary electrophoresis for high-sensitivity detection of trace chloro-phenols

Abstract

The present work developed a sensitive and selective method for the determination of 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) in an environmental water sample by molecularly imprinted magnetic nanoparticle (Fe₃O₄@MIP) based extraction coupled with capillary electrophoresis (CE). The highly selective, fast and effective sample pretreatment method with Fe₃O₄@MIPs can overcome the low sensitivity of the highly efficient capillary electrophoresis-ultraviolet detection method (CE-UV). In order to further improve the detection sensitivity, the analytes eluted from the Fe₃O₄@MIPs were analyzed by the on-line sample preconcentration large volume sample stacking (LVSS) technique with MEKC. Under optimal concentration conditions, signal enhancements of 781, 3276 and 8916-fold were achieved for 4-CP, 2,4-DCP and 2,4,6-TCP, respectively. The average recoveries of the three analytes in spiked water samples were 99.33–104.5% with a relative standard deviation (RSD) below 6.8%. The detection limits for 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol were 1.1 × 10⁻³, 2.13 × 10⁻⁴ and 6.68 × 10⁻⁵ μg mL⁻¹, respectively.