Molecularly Imprinted Monolithic Column for Selective On-Line Extraction of Enrofloxacin and Ciprofloxacin from Urine

Abstract

A simple on-line molecularly imprinted solid-phase extraction coupled with liquid chromatographic separation was developed for the simultaneous determination of enrofloxacin and its active metabolite ciprofloxacin from urine samples. The molecularly imprinted monolithic columns were synthesized in water-containing systems using norflorxacin as dummy template and methanol–water (5:1, v/v) as porogenic solvent, which reveal high affinity to enrofloxacin and ciprofloxacin in the aqueous environment. Due to the unique porous structure and flow-through channels existing in the network skeleton of the imprinted monolith, urine samples could be injected directly into the imprinted column, proteins and other biological matrix were quickly washed out and the analytes were selectively retained and enriched. Good linearity was obtained from 0.05 to 200 mg L−1 with relative standard deviations less than 3.1%. The recoveries were higher than 87% at three different concentrations and the limit of detection of the method was 0.01 mg L−1. Moreover, by increasing the injection volume, the sensitivity of the method could be further improved.