An Innovative Nanoparticle Modified Carbon Paste Microsensor for Ultrasensitive and Selective Detection of Danofloxacin in Environmental and Urinary Samples

An ultrasensitive and selective voltammetric microsensor (multiwalled carbon nanotube [MWCNT]/carbon black nanoparticle [nCB])-modified carbon paste microelectrode (mCPµE) with ultra-trace level detection limit is designed for the determination of danofloxacin (DAN) in real samples. The (MWCNT/nCB)-mCPµE consists of a carbon paste cavity microelectrode (MEC) modified with nCBs and MWCNTs. The nanostructure of the different MEC materials are characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Under optimal conditions, a wide linear range (2.5 × 10⁻⁹–2.5 × 10⁻⁷ mol L⁻¹) is obtained. The detection and quantification limits are estimated at 4.3 × 10⁻¹⁰ and 1.43 × 10⁻⁹ mol L⁻¹, respectively. For the measurement of DAN in the presence of many possible interfering chemical molecules, the suggested microsensor demonstrates remarkable selectivity. Analysis of the real samples confirms that the (MWCNT/nCB)-mCPµE is a suitable electrochemical sensor for the determination of DAN in wastewater and urine samples with satisfactory recoveries of 103.5%–104.6% and relative standard deviations less than 4.93%. Finally, in terms of sustainability (availability of materials used), analytical efficiency (precision and very low limit of quantification), and economic considerations (use of a very small quantity of materials), the proposed method outperforms previously reported methods.