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Enantioseparation and sensitive analysis of ofloxacin by poly(3,4-dihydroxyphenylalanine) functionalized magnetic nanoparticles-based solid phase extraction in combination with on-line concentration capillary electrophoresis

Xiao, Xue, Wu, Jia, Li, Zhenqun, Jia, Li
Journal of chromatography 2019 v.1587 pp. 14-23
adsorbents, adsorption, blood, blood sampling, capillary electrophoresis, cattle, chromatography, desorption, detection limit, dihydroxyphenylalanine, drugs, enantiomers, magnetism, methanol, nanoparticles, ofloxacin, pH, solid phase extraction, sonication, urine
Chiral separation of low concentrations of pharmaceuticals in biofluids is a challenge task. In this study, a method is developed to enantioseparate trace amount of racemic ofloxacin in urine and bovine blood by combining magnetic solid phase extraction (MSPE) and chiral capillary electrophoresis (CE). Poly(3,4-dihydroxyphenylalanine) modified magnetic nanoparticles (polyDOPA-MNPs) are prepared and used as the adsorbents in MSPE to extract ofloxacin. The polyDOPA-MNPs are spherical, about 130 nm in diameter and the polyDOPA shell is about 3 nm. The extraction process of polyDOPA-MNPs for ofloxacin includes 2 min adsorption and 2 min desorption with the assistance of sonication. Under the optimized MSPE conditions (3 mg polyDOPA-MNPs as adsorbents, sample pH 7.0, 75% (v/v) AcOH in methanol as eluent, adsorption time 2 min, desorption time 2 min), the extraction efficiency of ofloxacin is 95%. In chiral CE, pressure-assisted field-enhanced sample injection (PA-FESI) is developed to improve the detection sensitivity of ofloxacin enantiomers. The MSPE/PA-FESI chiral CE method demonstrates a good linearity in the concentration range of 0.01–0.06 μg/mL, with a detection limit as low as 0.29 ng/mL. The feasibility of the method is verified by the successful determination of trace amounts of ofloxacin enantiomers in spiked urine and bovine blood samples.