A New Approach for the Determination of Metronidazole Using Switchable Solvent Coupled with Au-MWCNTs-Modified Electrochemical Sensor

In this work, a new liquid-phase microextraction method coupled with an electrochemical technique using a switchable solvent was proposed for the determination of metronidazole. The extraction solvent used was dipropylamine (DPA), which exhibited switchable hydrophilicity. This means that it can become miscible or immiscible when in contact with carboxylic acids in the aqueous sample. The metronidazole was then measured using a glassy carbon electrode that was modified with Au- multiwalled carbon nanotubes (MWCNTs). The effect of different parameters such as the type and amount of trigger, the addition of salt, and the volume of extraction solvent on the efficiency of switchable hydrophilic solvent-based liquid-phase microextraction (SHS-LPME) was investigated using the one-factor-at-a-time method. After optimizing the conditions, the linear calibration curve was obtained in the concentration range of 0.005–250 μmol/L. Accordingly, the limit of quantification (LOQ) of 0.005 μmol/L and the limit of detection (LOD) of 0.0015 μmol/L were obtained, respectively.