Electrochemical sensing of Hg(ii) in chicken liver and snail shell extract samples using novel modified SDA/MWCNT electrodes.

Background: Antibiotics are extensively used as therapeutic, prophylactic and growth promoting agents in the poultry industry. However, their widespread use resulted in the presence of residuals in poultry meat and offals potentially leading to public health hazards. The present research was done to assess the distribution and concentration of residual antibiotics in chicken meat and liver samples. Methods: Ninety chicken meat and liver samples were collected and transferred to laboratory. Presence and concentration of residual tetracyclines, sulfonamides and trimethoprim were assessed using the Liquid Chromatography -Tandem Mass Spectrometry technique. Results: There were no detectable concentrations of tetracyclines in all studied samples. Twenty-eight out of 90 (31.11%) raw meat and 31 out of 90 (34.44%) liver samples were positive for residual sulfonamides. Prevalence of positive meat and liver samples for residual sulfachloropyrazine, sulfadimethoxine and trimethoprim antibiotics were 16.66%, 5.55% and 8.88% and also16.66%, 5.55% and 11.11%, respectively. Sulfathiazole residue was only detected in 1.11% of chicken liver samples. Chicken liver samples had the higher concentrations of all detected residual sulfonamides. Sulfachloropyrazine had the highest concentration in raw chicken meat (20.8±1.88 µg/kg) and liver (24.4±1.54 µg/kg) samples, while sulfadimethoxine had the lowest (6.05±0.25 µg/kg and 9.26±0.36 µg/kg, respectively). Conclusion: All detected concentrations of residual sulfonamides were lower than Maximum Residue Limits (MRLs). Presence of residual antibiotics represents a serious public health treat regarding the occurrence of antibiotic resistant bacterial strains. LC MS/MS has been introduced as a sensitive and specific technique for monitoring and surveillance of residual antibiotics in chicken samples.

Square wave anodic stripping voltammetry (SWASV) is an effective method for the detection of Cd(II), but the presence of Pb(II) usually has some potential and negative interference on the SWASV detection of Cd(II). In this paper, a novel method was proposed to predict the concentration of Cd(II) in the presence of Pb(II) based on the combination of chemically modified electrode (CME), machine learning algorithms (MLA) and SWASV. A Bi film/ionic liquid/screen- printed electrode (Bi/IL/SPE) was prepared and used for the sensitive detection of trace Cd(II). The parameters affecting the stripping currents were investigated and optimized. The morphologies and electrochemical properties of the modified electrode were characterized by scanning electron microscopy (SEM) and SWASV. The measured SWASV spectrograms obtained at different concentrations were used to build the mathematical models for the prediction of Cd(II), which taking the combined effect of Cd(II) and Pb(II) into consideration on the SWASV detection of Cd(II), and to establish a nonlinear relationship between the stripping currents of Pb(II) and Cd(II) and the concentration of Cd(II). The proposed mathematical models rely on an improved particle swarm optimization-support vector machine (PSO-SVM) to assess the concentration of Cd(II) in the presence of Pb(II) in a wide range of concentrations. The experimental results suggest that this method is suitable to fulfill the goal of Cd(II) detection in the presence of Pb(II) (correlation coefficient, mean absolute error and root mean square error were 0.998, 1.63 and 1.68, respectively). Finally, the proposed method was applied to predict the trace Cd(II) in soil samples with satisfactory results. Keywords: square wave anodic stripping voltammetry (SWASV), particle swarm, support vector machine, screen-printed electrode, heavy metals, Cd detection, soil pollution DOI: 10.25165/j.ijabe.20171005.2863 Citation: Zhao G, Wang H, Yin Y, Liu G. PSO-SVM applied to SWASV studies for accurate detection of Cd(II) based on disposable electrode. Int J Agric & Biol Eng, 2017; 10(5): 251–261.

Inexpensive and green electrochemical sensor for the determination of Cd(II) and Pb(II) by square wave anodic stripping voltammetry in bivalve mollusks

The fabrication and evaluation of a glassy carbon electrode (GCE) modified with self-doped polyaniline nanofibers (SPAN)/mesoporous carbon nitride (MCN) and bismuth for simultaneous determination of trace Cd2+ and Pb2+ by square wave anodic stripping voltammetry (SWASV) are presented here. The morphology properties of SPAN and MCN were characterized by transmission electron microscopy (TEM), and the electrochemical properties of the fabricated electrode were characterized by cyclic voltammetry (CV). Experimental parameters, such as deposition time, pulse potential, step potential, bismuth concentration and NaCl concentration, were optimized. Under the optimum conditions, the fabricated electrode exhibited linear calibration curves ranging from 5 to 80 nM for Cd2+ and Pb2+. The limits of detection (LOD) were 0.7 nM for Cd2+ and 0.2 nM for Pb2+ (S/N = 3). Additionally, the repeatability, reproducibility, anti-interference ability and application were also investigated, and the proposed electrode exhibited excellent performance. The proposed method could be extended for other heavy metal determination.

In this study, a stable, sensitive electrochemical sensor was fabricated by the electrochemical codeposition of reduced graphene oxide (rGO) and gold nanoparticles on a glassy carbon electrode (rGO-Aunano/GCE) using cyclic voltammetry (CV), which enabled a simple and controllable electrode modification strategy for the determination of trace As(III) by square wave anodic stripping voltammetry (SWASV). SWASV, CV, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the electrochemical properties and morphology of the proposed sensing platform. The number of sweep segments, the deposition potential and the deposition time were optimized to obtain ideal sensitivity. The presence of rGO from the electroreduction of graphene oxide on the sensing interface effectively enlarged the specific surface area and consequently improved the preconcentration capacity for As(III). The rGO-Aunano/GCE sensor exhibited outstanding detection performance for As(III) due to the combined effect of Aunano and rGO formed during the electroreduction process. Under the optimized conditions, a linear range from 13.375 × 10−9 to 668.75 × 10−9 mol/L (1.0 to 50.0 μg/L) was obtained with a detection limit of 1.07 × 10−9 mol/L (0.08 μg/L) (S/N = 3). The reproducibility and reliability of the rGO-Aunano/GCE sensor were also verified by performing 8 repetitive measurements. Finally, the rGO-Aunano/GCE sensor was used for the analysis of real samples with satisfactory results.

A novel and effective method for immobilization of active ruthenium (II) bipyridine complex on screen printed gold electrode surface was developed for simultaneous determination of Cd (II) and Pb (II) in an environmental water sample. The electrostatic interaction between negatively charged graphene oxide (GO) or citrate-capped gold nanoparticles (AuNPs) and positively charged ruthenium (II) bipyridine complex ([Ru(bpy)3]2+) was studied with the incorporation of cation exchanging Nafion polymer, which enhanced electron transfer rate, reduced the interference caused by active compounds and results in long term stability. The comparison between the hybrid Ru-GO/Nafion and Ru-Au/Nafion nanocomposites’ behavior was electrochemically investigated in this paper through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave anodic stripping voltammetry (SWASV). Additionally, the surface morphologies of the screen-printed electrode were evaluated using energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). The proposed Ru-GO/Nafion sensor exhibited a higher sensitivity towards cadmium ion with a detection limit of 4.2 ppb compared to the Ru-Au/Nafion assay, which reveals low sensitivity with a limit of detection of 12.01 ppb. The developed assays show excellent electrochemical performance towards lead ions with a detection limit of 5.3 ppb and 2.5 ppb for Ru-GO/Nafion and Ru-Au/Nafion, respectively, indicating that the lead ions can be accumulated more on the surface of Ru-Au/Nafion SPGE. The hybrid nanocomposite assays were successfully employed in river and tap water samples and validated using Atomic Absorption Spectroscopy (AAS).

Novel synthesized SABA/MWCNTs composite to detect Cd2+ and Pb2+ ions in real samples of rice water, tobacco extract and raw milk

Synthesis of a three-dimensional (BiO)2CO3@single-walled carbon nanotube nanocomposite and its application for ultrasensitive detection of trace Pb(II) and Cd(II) by incorporating Nafion

Sensitive stripping voltammetric determination of Cd(II) and Pb(II) by a Bi/multi-walled carbon nanotube-emeraldine base polyaniline-Nafion composite modified glassy carbon electrode

A new modified carbon paste electrode using N1-hydroxy-N1,N2-diphenylbenzamidine for the square wave anodic stripping voltammetric determination of Pb(II) in environmental samples

Individual and Simultaneous Stripping Voltammetric and Mutual Interference Analysis of Cd2+, Pb2+ and Hg2+ with Reduced Graphene Oxide-Fe3O4 Nanocomposites

Rapid and simultaneous electrochemical method to measure copper and lead in canine liver biopsy

In this work, an antimony trioxide-modified multi-walled carbon nanotube paste electrode (Sb2O3/CNTPE) was employed for determination of Cu2+ ions by using square wave anodic stripping voltammetry (SWASV) in the presence of 8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) as a chelating agent. The field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS) and electrochemical impedance spectroscopy (EIS) methods were applied to estimate the morphology and properties of the modified electrode. Measurements related to SWASV were taken in 0.6 M HCl at −1.0 V versus Ag|AgCl|KCl (3 M) for 90 s (deposition step). After equilibrium time of 15 s, an ASV appeared at 0.0 V versus Ag|AgCl|KCl (3 M) (stripping step). The sensor depicted a fairly linear response for Cu2+ in the concentration range of 2–100 ppb with appropriate detection limit about 0.39 ppb and limit of quantification about 1.3 ppb. The stability of the modified electrode during 7 weeks and its behavior in the presence of some metal ions was evaluated. The practical applicability of the Sb2O3/CNTPE was established on the voltammetric determination of Cu2+ in tap water as a sample.

Fabrication of carbon nanotube and synthesized Octadentate ligand modified electrode for determination of Hg (II) in Sea water and Lake water using square wave anodic stripping voltammetry

A glassy carbon electrode (GCE) was chemically modified with p ‐propylaniline/L–Cys molecules for the sensitivity determination of Cd(II), Pb(II) and Hg(II) in aqueous medium. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) characterized passivation of the electrode and 97.4 % surface coverage with p ‐propylaniline/L–Cys molecules. Nanofilm coating was characterized by cyclic voltammetry (CV), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR) techniques to observe the surface morphology. The porous structure uniformly distributed thiol, amine and carboxylate groups throughout the coating to selectively coordinate and preconcentrate the three metal ions. Under the optimized conditions (deposition potential: −1 V vs. SCE, deposition time: 90s), square wave anodic stripping voltammetry (SWASV) electroanalysis results indicated the linear increment of electrochemical signals with an increase in the concentration of Cd(II), Pb(II) and Hg(II) in range of 2.5 to 30 μg L −1 . Based on the calibration plot, limit of detection (LOD, 3 σ /m) are 0.103 μg L −1 , 0.055 μg L −1 and 0.01 μg L −1 respectively. Analysis of drinking and tap water samples demonstrated precision and accuracy of the electrode as a prospective sensor for analysis of more complex aqueous environmental matrices.