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This work reports the construction of screen‐printed electrode (SPE) modified with carbon black (CB) and magnetic Fe3O4 nanoparticles coated with molecularly imprinted polymer (mag@MIP) based on an alternative low‐cost approach. The proposed device was used for the sensitive and selective voltammetric determination of the antibiotic ciprofloxacin. The results obtained from cyclic voltammetry pointed to the improvement of the SPE response toward the irreversible oxidation of ciprofloxacin after the modification of the electrode surface with CB‐based film and the magnetic preconcentration of mag@MIP containing adsorbed ciprofloxacin molecules. Compared to the non‐molecularly imprinted sensor (mag@NIP), the presence of cavities selective for ciprofloxacin recognition in the mag@MIP nanoparticles accounted for the improvement in analytical signal of the molecularly imprinted sensor. The application of differential pulse voltammetry for ciprofloxacin determination yielded a linear response in the concentration range of 0.5 to 7.0 μmol L−1. The repeatability and interference tests results showed that the proposed electrochemical sensor has good measurement accuracy and selectivity. The proposed device was applied for the voltammetric determination of ciprofloxacin in river water and synthetic urine samples, where recovery rates close to 100 % were recorded for all the samples. The quantification data obtained from the application of the proposed voltammetric method were quite consistent with those of the HPLC reference method. [ABSTRACT FROM AUTHOR]

The non‐enzymatic electrochemical sensing of hydrogen peroxide (H2O2) is described. This study utilized a 3D bicontinuous nanoporous platinum‐gold alloy‐based sensor (NP−Pt(Au) electrode), which has a morphology that resembles a molecular sieve. SEM and CV were used to evaluate the morphological and electrochemical characteristics of the NP−Pt(Au) electrodes. The cathodic voltammetric response of H2O2 was enhanced at the NP−Pt(Au) as compared to planar Pt electrodes. The nanoporous electrode was able to maintain the H2O2 voltammetric profile even in the presence of the biofouling agent, serum albumin. Its application as a non‐enzymatic sensor for the amperometric measurement of H2O2 was explored. [ABSTRACT FROM AUTHOR]

A porous electrode material combining the features of vertically aligned multi-walled carbon nanotubes (VAMWCNT) and diamond-like carbon films (DLC) have been developed for a highly sensitive electrochemical sensor. For working electrode preparation, DLC has been grown onto VAMWCNT, forming a porous, conductive and stable composite. The electrochemical performance of this DLC:VAMWCNT electrode has been investigated toward detection and analysis of three well-known molecules, namely paracetamol, codeine and caffeine. A ternary mixture of these analytes was simultaneously determined under optimum experimental conditions using square-wave voltammetry. Wide linear concentration ranges and the limits of detection of 3.34×10−7 mol L−1, 1.57×10−7 mol L−1 and 3.67×10−7 mol L−1 were obtained for paracetamol, codeine and caffeine, respectively. We conclude that the proposed voltammetric method and the DLC:VAMWCNT electrode comprise a reliable methodology for simultaneous determination of paracetamol, codeine and caffeine in biological matrix samples. [ABSTRACT FROM AUTHOR]

Pb2+ ions are highly toxic to living beings because they tend to bioaccumulate in the body. For this reason, the development of simpler, low‐cost, and easy‐to‐operate techniques that can detect and quantify low concentrations of metal ions would help to identify contaminating media and improve public health. This work proposes a Pb2+ voltammetric sensor based on a carbon paste electrode modified with hydrothermal biochar (hydrochar, HC) obtained from malt bagasse waste (HC/CPE). The obtained hydrochar was characterized by zero‐charge point, FT‐IR, XRD and thermogravimetry. The differential pulse adsorptive anodic stripping voltammetry (DPAdASV) technique was used to perform the Pb2+ determination. After optimizing important parameters for detecting Pb2+ ions and the parameters of the voltammetric technique employed, a linear response range of 0.50 to 7.06 μmol L−1 with a limit of detection (LOD) and limit of quantification (LOQ) of 55.0 and 181.5 nmol L−1 were achieved, respectively. The developed voltammetric procedure was applied towards the Pb2+ determination at tap water and river water samples, with excellent recoveries (ranging of 91.19 to 109.22 %), proving that the HC‐based electrode has great potential for detecting Pb2+ ions. Hydrothermal carbonization allowed the biomass to be converted into functionalized hydrochar, eliminating the need for subsequent functionalization/activation steps for use as a Pb2+ adsorbing material on the electrodic surface. The proposed sensor also proved to be easy to assemble and environmentally friendly by using biomass waste as the carbon material. Thus, the proposed sensor adds to the literature the possibility of simple and easy detection of metal ions with a waste reuse bias. [ABSTRACT FROM AUTHOR]