Development of a Disposable Electrochemical Sensor based on Nanocomposite/Ionic Liquid Assisted Hollow Fiber-Graphite Electrode for Measurement of Lorazepam Using Central Composite Design

In this study a new method of preconcentration, separation and efficient measuring of so-called hollow fiber solid / liquid phase microextraction has been introduced for the determination of trace amounts of lorazepam (LRZ) in water samples, urine and hair using differential pulse voltammetry. To this end, a hybrid adsorbent material was used that involved ionic liquid assisted magnetic multi-walled carbon nanotube as the extraction phase. Nanoparticles dispersed in the ionic liquid were placed inside the pores and channels of hollow polypropylene fiber. Then the pencil graphite electrode modified with multi-walled carbon nanoparticles was put into this fiber. This combined electrode was placed in a voltammetry cell and use as a working electrode. The electrochemical behavior of LRZ on the fabricated working electrode was investigated by differential pulse voltammetry (DPV) techniques and the obtained results confirmed its efficiency for sensing of LRZ. The study was approved using the Placktett-Burman design (PBD) for screening and central composite design (CCD) for the optimization of the process parameters. Under optimal conditions, a linear calibration curve was plotted for the concentration of analyte between 0.032 to 64.2 μM with a detection limit (LOD) (S/N=3) and limit of quantification (LOQ) of 0.003 μM and 0.06 μM respectively. The suggested method was successfully applied for screening real samples; domestic water, urine and hair for LRZ.