Dispersive micro-solid phase extraction using magnetic nanoparticle modified multi-walled carbon nanotubes coupled with surfactant-enhanced spectrofluorimetry for sensitive determination of lomefloxacin and ofloxacin from biological samples.

A dispersive micro-solid-phase extraction (D-μ-SPE) procedure coupled with surfactant-enhanced spectrofluorimetric detection was developed for determination of ofloxacin and lomefloxacin from biological and environmental samples. The D-μ-SPE procedure was performed using magnetic Fe3O4 nanoparticle grafted multi-walled carbon nanotube as an efficient adsorbent. The main factors affecting the signal enhancement (including surfactant concentration and pH) and extraction efficiency (including pH, extraction time, sample volume, amount of magnetic adsorbent, and desorption conditions) were investigated in detail. Under the optimized conditions, the calibration curves were linear (R(2)˃0.9995) over the concentration range of 50-450 ng mL(-1) with detection limits (LOD) of 12 and 15 ng mL(-1) for ofloxacin and lomefloxacin respectively. The relative standard deviation (RSD %) of 1.9 and 2.1% (C=100 ng mL(-1), n=5) and the enrichment factor of 192 and 188 were achieved for ofloxacin and lomefloxacin respectively. Finally, the method was successfully applied to the extraction and preconcentration of these drugs in biological (plasma and urine) samples.