A Sensitive Sensor Based on Single‐walled Carbon Nanotubes: Its Preparation, Characterization and Application in the Electrochemical Determination of Drug Clorsulon in Milk Samples

Abstract

Within this paper, a glassy carbon electrode modified with single‐walled carbon nanotubes (SWCNTs−GCE) was prepared, and employed for the determination of clorsulon (Clo), which is a frequently used veterinary drug against common liver fluke. The comprehensive topographical and electrochemical characterizations of bare GCE and SWCNTs−GCE were performed by atomic force microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. Significantly enhanced electrochemical characteristics of SWCNTs−GCE toward a ferrocyanide/ferricyanide redox couple was observed when compared to bare GCE. Further, the prepared sensor was applied for the voltammetric determination of Clo, which was electrochemically investigated for the first time in this work. Voltammetric experiments were performed using square‐wave voltammetry with optimized parameters in phosphate buffer solution, pH 6.8, which was selected as the most suitable medium for the determination of Clo. The corresponding current at approx. +1.1 V increased linearly with Clo concentration within two linear dynamic ranges of 0.75–4.00 μmol L−1 (R2=0.9934) and 4.00–15.00 μmol L−1 (R2=0.9942) with a sensitivity for the first calibration range of 0.76 μA L μmol−1, a limit of detection of 0.19 μmol L−1, and a limit of quantification of 0.64 μmol L−1. The developed method was subsequently applied for quantitative analysis of Clo in milk samples with results proving high repeatability and recovery.

Electrochemical Biosensor Employing Bi2S3 Nanocrystals-Modified Electrode for Bladder Cancer Biomarker Detection

“…The basic electrochemical characteristics of the modified electrodes were obtained by CV, DPV and EIS utilizing 5 mM (Fe[CN] 6 ) 3− / 4− and 0.5 M KCl as REDOX mediator. As shown in Figure S1, the effective surface areas (A eff ) of bare and modified sensors were calculated to be 0.134 cm 2 and 0.109 cm 2 , which may be ascribed to the better conductivity of carbon conductor electrodes than bismuth sulfide semiconductor nanocrystals [29]. For purpose of comparison, a bare electrode (C), Bi 2 S 3 NCs-modified electrode (C/Bi 2 S 3 ), and an antibody-coated NCs-modified electrode before (C/Bi 2 S 3 /Antibody) and after BSAblocking (C/Bi 2 S 3 /Antibody/BSA) were prepared and tested measured in the presence of PBS (0.067 M) containing above REDOX mediator.…”

Composite Electrodes Based on Carbon Materials Decorated with Hg Nanoparticles for the Simultaneous Detection of Cd(II), Pb(II) and Cu(II)

“…Table 1 summarizes the analytical parameters found for each metal (Cd 2+ , Pb 2+ and Cu 2+ ). The electroactive area (A) can be estimated from Ip using the Randles-Sevčik equation [43]:…”

Determination of Chemical Oxygen Demand (COD) Using Nanoparticle-Modified Voltammetric Sensors and Electronic Tongue Principles

“…Unfortunately, the KHP substance is very hard to be oxidized with these four electrodes, but this is a fact that can be also assessed from these measurements. To demonstrate the enhanced performance of the deposited electrode E1, the active surface areas of the four electrodes were calculated according to the Randles-Sevcik Equation (1) [25,26], in which n is the number of electrons involved in the redox reaction, F is the Faraday's constant (96,485 C•mol −1 ), A is the electrode active area in cm −2 , c is the concentration of electroactive substance (mol•cm −3 ), 𝑣𝑣 is the scan rate (V•s −1 ), R is the gas constant (8.314 J•mol −1 •K −1 ), T is the temperature in K, and D is the analyte diffusion coefficient (6.32•10 −6 •cm −2 •s −1 ). Seven cyclic voltammograms of each electrode at different scan rates (10, 25, 50, 100, 200, 300, and 500 mV•s −1 ) were recorded in the solution of 5 mmol•L −1 [Fe(CN)6] 3−/4− .…”