Visible Light Photoelectrochemical Sensor for Acetaminophen Determination using a Glassy Carbon Electrode Modified with BiVO4 Nanoparticles

A new and simple photoelectrochemical (PEC) sensor using a glassy carbon electrode (GCE) modified with bismuth vanadate (BiVO₄) nanoparticles and dihexadecyl phosphate (DHP) film was useful for acetaminophen (AC) determination. In 0.2 mol L⁻¹ phosphate buffer (pH=9), the GCE without modification exhibited the smaller photocurrent (0.86 μA) when compared with GCE modified with 1.0 mg mL⁻¹ or 2.0 mg mL⁻¹ BiVO₄ nanoparticles suspension (5.9 and 34 μA, respectively). Based on the photocurrent signal generated through the interaction between GCE, BiVO₄ and the energy of visible light a chronoamperometric method for AC determination was developed. The AC linear range concentration from 0.099 to 0.99 μmol L⁻¹ and limits of detection and quantification of 0.027 and 0.091 μmol L⁻¹, respectively, was obtained. The proposed method was applied to the AC determination in commercial drugs and tap water with satisfactory accuracy and precision. Moreover, the PEC construction was easy and had a short response time, which might confer higher sample throughput for the method.     

A Self‐assembled L‐Cysteine and Electrodeposited Gold Nanoparticles‐reduced Graphene Oxide Modified Electrode for Adsorptive Stripping Determination of Copper

Glassy carbon electrode (GCE) modified with L‐cysteine and gold nanoparticles‐reduced graphene oxide (AuNPs‐RGO) composite was fabricated as a novel electrochemical sensor for the determination of Cu²⁺. The AuNPs‐RGO composite was formed on GCE surface by electrodeposition. The L‐cysteine was decorated on AuNPs by self‐assembly. Physicochemical and electrochemical properties of L‐cysteine/AuNPs‐RGO/GCE were characterized by scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy, Raman spectroscopy, X‐ray diffraction, cyclic voltammetry and adsorptive stripping voltammetry. The results validated that the prepared electrode had many attractive features, such as large electroactive area, good electrical conductivity and high sensitivity. Experimental conditions, including electrodeposition cycle, self‐assembly time, electrolyte pH and preconcentration time were studied and optimized. Stripping signals obtained from L‐cysteine/AuNPs‐RGO/GCE exhibited good linear relationship with Cu²⁺ concentrations in the range from 2 to 60 μg L⁻¹, with a detection limit of 0.037 μg L⁻¹. Finally, the prepared electrode was applied for the determination of Cu²⁺ in soil samples, and the results were in agreement with those obtained by inductively coupled plasma mass spectrometry.     

Development of Electrochemical Platform Based on Molecularly Imprinted Poly(methacrylic acid) Grafted on Iniferter-modified Carbon Nanotubes for 17β-Estradiol Determination in Water Samples

This paper describes the development of a new electrochemical sensor for 17β-estradiol (E2) determination based on glassy carbon electrode (GCE) modified with molecularly imprinted polymer grafted onto iniferter-multiwall carbon nanotubes surface (MIP-MWCNT) and dihexadecyl-hydrogen-phosphate (DHP). The electrochemical method was based on closed-circuit preconcentration of E2 in 0.1 mol L⁻¹ phosphate buffer (pH 7.0) during 500 s. Upon preconcentration, E2 was determined by differential pulse voltammetry (DPV) exhibiting a limit of detection of 0.01 μmol L⁻¹. The sensor exhibited higher selectivity toward E2 and it was applied for E2 determination in natural water samples, with accuracy attested by HPLC-DAD.     

Electrochemical Determination of Fenitrothion Organophosphorus Pesticide Using Polyzincon Modified‐glassy Carbon Electrode

In this paper, a glassy carbon electrode (GCE) was modified with polyzincon. The modified electrode was used as a simple, inexpensive and highly sensitive electrochemical sensor for the determination of organophosphorus pesticide fenitrothion. To fabricate the electrochemical sensor, GCE was immersed in 0.10 mmol L⁻¹ zincon solutions at pH 7.0 and then successively scanned between −1.00 to 2.20 V (vs . Ag/AgCl) at a scan rate of 70 mV s⁻¹ for six cycles. The morphology and structure of the polyzincon were studied with atomic force microscopy and scanning electron microscopy. A comparison of the electrochemical behavior of fenitrothion on the unmodified and polyzincon modified‐GCE showed that in the modified electrode not only the oxidation peak current increased, but also the overpotential shifted to lower one. The experimental conditions such as sample solution pH, accumulation potential, and time were optimized. The differential pulse voltammetric responses of fenitrothion at potential about −0.60 V was used for the determination of fenitrothion. The peak current increased with increasing the concentration of fenitrothion in the range of 5 to 8600 nmol L⁻¹ with a detection limit of 1.5 nmol L⁻¹. Finally, the electrochemical sensor was used for the analysis of fenitrothion in water and fruit samples.     

Simultaneous Electrochemical Detection of Co(II) and Cu(II) by 1‐Diazo‐2‐Naphthol‐4‐Sulfonic Acid/MWCNTs Modified Electrode

This work describes a simple preparation of 1‐diazo‐2‐naphthol‐4‐sulfonic acid (1,2,4‐acid) and multiwalled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) for the simultaneous detection of Co(II) and Cu(II). MWCNTs, with their good conductivity and large surface area, were drop‐casted onto the surface of the GCE prior to the electrodeposition of 1,2,4‐acid, a metal chelating agent. Co(II) and Cu(II) were simultaneously measured by differential pulse anodic stripping voltammetry (DPASV) in a batch system. Under optimum conditions, the linear range of Co(II) was between 0.10 and 2.5 μg mL⁻¹ with an LOD of 80 ng mL⁻¹. Two linear ranges were obtained for Cu(II), 0.0050 to 0.030 μg mL⁻¹ and 0.040 to 0.25 μg mL⁻¹,with an LOD of 2.4 ng mL⁻¹. The method offered a high operational stability for up to 52 measurements (RSD=3.4 % for Co(II) and 2.6 % for Cu(II)) and good reproducibility (RSD=1.2 % for Co(II) and 1.7 % for Cu(II)). In the simultaneous detection of Co(II) and Cu(II), there was no effect from common interferences found in wastewater. The method was successfully applied in real water samples with good recoveries (88.2±0.8 to 102.0±0.8 % for Co(II) and 96.5±0.4 to 103.8±0.9 % for Cu(II)) and the results were in good agreement with those obtained from inductively coupled plasma optical emission spectrometry (ICP‐OES) (P >0.05).     

Adsorptive Stripping Voltammetric Detection of Single‐Stranded DNA at Electrochemically Modified Glassy Carbon Electrode

Electrochemically modified glassy carbon electrode (GCE) was used to study the electrochemical oxidation and detection of denatured single‐stranded (ss) DNA by means of adsorptive stripping voltammetry. The modification of GCE, by electrochemical oxidation at +1.75 V (vs.SCE) for 10 min and cyclic sweep between +0.3 V and ?1.3 V for 20 cycles in pH 5.0 phosphate buffer, results in 100‐fold improvement in sensitivity for ssDNA detection. We speculated that the modified GCE has a high affinity to single‐stranded DNA through hydrogen bond (specific static adsorption). Single‐stranded DNA can accumulate at the GCE surface at open circuit and produce a well‐defined oxidation peak corresponding to the guanine residues at about +0.80 V in pH 5.0 phosphate buffer, while the native DNA gives no signal under the same condition. The peak currents are proportional to the ssDNA concentration in the range of 0–18.0 μg mL^?1. The detection limit of denatured ssDNA is ca. 0.2 μg mL^?1 when the accumulation time is 8 min at open circuit. The accumulation mechanism of ssDNA on the modified GCE was discussed.     

Ferrocene Decorated N-doped Carbon Modified Electrode with Enhanced Electrocatalytic Activity towards Non-enzymatic Glucose Detection

The nitrogen doped carbon (NDCN) have been synthesized by flame synthetic method to prepare ferrocene decorated NDCN. The hydrolysis product (FC-SH) of ferrocene benzyne derivative (FC-SAc) was immobilized onto NDCN modified GCE and used for glucose detection with high sensitivity. Cyclic voltammetric analysis reveal that FC-S-NDCN/GCE exhibit excellent activity for glucose oxidation when compared to FC/GCE. The FC-S-NDCN/GCE with wide linear responses range from 0.001 to 0.01 mM with the regression co-efficient of 0.998. The FC-S-NDCN/GCE show low detection limit (LOD) of 0.08 μM and exhibit sensitivity of 1580 μA mM⁻¹ cm⁻². The FC-S-NDCN glucose sensor exhibit wide linear range, high sensitivity and lower detection limit on determination of glucose.     

Over‐Oxidized Poly (Phenol Red) Film Modified Glassy Carbon Electrode for Anodic Stripping Voltammetric Determination of Ultra‐Trace Antimony (III)

In this study, we introduce a very sensitive and selective method for the differential pulse anodic stripping determination of Sb(III) ion on the over‐oxidized poly(phenol red) modified glassy carbon electrode (PPhRed_ox/GCE) in 0.1 mol L^‐1 HCl medium. The formation of both poly(phenol red) and over‐oxidized poly(phenol red) film on the electrode surfaces were characterized by electrochemical impedance spectroscopy, X‐ray photoelectron spectroscopy and scanning electron microscopy techniques. An anodic stripping peak of Sb(III) was observed at 0.015 V on the PPhRed_ox/GCE. Higher anodic stripping peak current of Sb(III) was obtained at PPhRed_ox/GCE compared with both bare GCE and poly(phenol red) film modified GCE (PPhRed/GCE). The calibration graph consisted of two linear segments of 0.044 ‐ 1.218 μg L⁻¹ and 3.40 – 18.26 μg L⁻¹ with a detection limit of 0.0075 μg L⁻¹. The proposed over‐oxidized polymer film modified electrode was applied successfully for the analysis of antimony in different spiked water samples. Spiked recoveries for water samples were obtained in the range of 93.0–103.0%. The accuracy of the method was also verified through the analysis of standard reference materials (SCP SCIENCE‐EnviroMAT™ EP−L‐2).     

Voltammetric Determination of an Anti-rheumatoid Drug Acemetacin on Graphite Flake Paste Electrode and Glassy Carbon Electrode

In this study, a simple and sensitive square wave voltammetric procedure has been developed for the determination of acemetacin (ACM) at graphite flake paste electrode (GFPE) and glassy carbon electrode (GCE). Under optimized conditions, the dependence of ACM peak current on its concentration showed wide linear range: 0.03–1.0 μmol L⁻¹ and 0.7–15.0 μmol L⁻¹ at GFPE and GCE, respectively. The developed method was successfully applied for the determination of ACM in pharmaceuticals and spiked urine with satisfying recoveries. The electrochemical oxidation of ACM is an irreversible process controlled by mixed nature of the mass transfer process.     

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

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.     

Development of an Electrochemical Sensor to Detect Dopamine and Ascorbic Acid Based on Neodymium (III) Oxide and Chitosan

Neodymium (III) oxide (Nd_Ox) was dispersed in chitosan dissolution and deposited on a glassy carbon electrode (chitosan‐Nd_Ox/GCE). The surface properties of the chitosan‐Nd_Ox/GCE were evaluated with FeCN₆⁻³ solution using cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode was used in the determination of individual dopamine (DP) and ascorbic acid (AA) with square wave adsorptive voltammetry. Under optimal parameters (pH 4.0; accumulation time; t_ACC 60s and accumulation potential; E_ACC 0.10 V) for DP and (pH 3,0; t_ACC 60s and; E_ACC −0.20 V) for AA, anodic peak currents were proportional to the concentration of DP and AA between 0.90 and 17.0 μmolL⁻¹, with detection limit of 0.079 μmolL⁻¹ for DP and 0.12 μmolL⁻¹ for AA. The sensor was used in the determination of DP and AA in human urine samples and vitamin C tablets with consistent results. The new sensor is easy to develop. In addition, the sensitivity in particular for AA was improved compared with previous work.     

Fe3O4 Nanorods-RGO-ionic Liquid Nanocomposite Based Electrochemical Sensor for Aflatoxin B1 in Ground Paprika

A novel and sensitive method for the determination of aflatoxin B1 (AFA−B1) in ground paprika using a methyltrioctylammonium chloride ionic liquid (IL), iron oxide nanorods (Fe₃O₄ nanorods) and reduced graphene oxide (RGO) fabricated glassy carbon electrode (GCE) was developed. The synthesized nanoparticles, nanocomposites and modified electrode surfaces were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA/DSC) and x-ray diffraction (XRD) analyses. Moreover, the electrochemical performance of the developed sensor was determined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The obtained results demonstrate that the sensitivity of AFA−B1 is significantly enhanced on RGO-Fe₃O₄ nanorods-IL-GCE in comparison with bare GCE, RGO-GCE and RGO-Fe₃O₄ nanorods-GCE. The redox peak currents of AFA−B1 exhibited good linear relationship with its concentration in the range from 0.02 to 0.33 ng mL⁻¹ with detection limit of (LOD) 0.03 ng mL⁻¹ and limit of quantification (LOQ) 0.36 ng mL⁻¹ respectively (S/N=3). In addition, the fabricated electrode showed good stability and reproducibility. The proposed technique was effectively applied to identify the AFA−B1 in real ground paprika samples with acceptable results.     

A Novel Electrochemical Glassy Carbon Electrode Modified with Carbon Black and Glyceline Deep Eutectic Solvent within a Crosslinked Chitosan Film for Simultaneous Determination of Acetaminophen and Diclofenac

Glyceline, reline, or ethaline deep eutectic solvents and carbon black nanoparticles within a crosslinked chitosan film are investigated as glassy carbon electrode modifiers for the first time. The selected 5 mg mL⁻¹ glyceline modified GCE was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. Simultaneous determination of acetaminophen and diclofenac by differential pulse adsorptive stripping voltammetry (DPAdSV) presented limits of detection of 2.6×10⁻⁸ and 5.2×10⁻⁸ mol L⁻¹ for acetaminophen and diclofenac, respectively, in pharmaceutical and biological samples. The obtained results were compared with those obtained by HPLC at a confidence level of 95 %.     

Selective Electroanalysis of Ascorbic Acid Using a Nickel Hexacyanoferrate and Poly(3,4‐ethylenedioxythiophene) Hybrid Film Modified Electrode

The mixed‐valent nickel hexacyanoferrate (NiHCF) and poly(3,4‐ethylenedioxythiophene) (PEDOT) hybrid film (NiHCF‐PEDOT) was prepared on a glassy carbon electrode (GCE) by multiple scan cyclic voltammetry. The films were characterized using atomic force microscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, X‐ray diffraction, and electrochemical impedance spectroscopy (AC impedance). The advantages of these films were demonstrated for the detection of ascorbic acid (AA) using cyclic voltammetry and amperometric techniques. The electrocatalytic oxidation of AA at different electrode surfaces, such as the bare GCE, the NiHCF/GCE, and the NiHCF‐PEDOT/GCE modified electrodes, was determined in phosphate buffer solution (pH 7). The AA electrochemical sensor exhibited a linear response from 5×10⁻⁶ to 1.5×10⁻⁴ M (R²=0.9973) and from 1.55×10⁻⁴ to 3×10⁻⁴ M (R²=0.9983), detection limit=1×10⁻⁶ M, with a fast response time (3 s) for AA determination. In addition, the NiHCF‐PEDOT/GCE was advantageous in terms of its simple preparation, specificity, stability and reproducibility.     

Design of Electrochemically Modified fMWCNT‐pencil Graphite Electrode Decorated with Cu and Ag Nanofilm and its Electrocatalytic Behavior Towards Imazethapyr

Herein, a facile procedure was developed for designing an electrochemical sensor based on pencil graphite electrode modified with electrochemically synthesized silver and copper nanoparticles (AgNP and CuNP) supported on functionalized multiwalled carbon nanotubes (f MWCNTs). The electrochemical and morphological characterization was carried out by cyclic voltammetry, Electrochemical Impedance Spectroscopy, Powder X‐ray diffraction, Field Emission Scanning Electron Microscopy, Transmission electron microscopy and Atomic Force Microscopy. The designed sensor exhibited electrocatalytic behavior towards the reduction of Imazethapyr. Results indicates the combination of AgNPs, CuNPs and f MWCNTs on PGE produced remarkable enhancement in electrocatalytic and sensing properties. Various electro‐kinetic parameters like R_ct, k_app, n, α, E⁰, k⁰, Γ, D and k have been evaluated by CV, impedance and Chronoamperometric studies. The electrochemical performance was improved by optimizing the effect of pH, scan rate, amount of f MWCNTs and deposition parameters of AgNP and CuNP. The sensor was efficaciously applied for determination of Imazethapyr and exhibited a linear correlation in the concentration range of 0.01–5.0 μg mL⁻¹ with low detection limits, 0.159 ng mL⁻¹ using AdSWV. The fabricated sensor exhibited good accuracy, acceptable stability and high efficacy for quantitative determination of Imazethapyr in real samples with notable recoveries ranging from 98 % to 100.2 %.     

Determination of Imidacloprid Based on the Development of a Glassy Carbon Electrode Modified with Reduced Graphene Oxide and Manganese (II) Phthalocyanine

An electrochemical sensor of glassy carbon electrode modified with reduced graphene oxide and manganese (II) phthalocyanine (GCE/rGO/MnPc) was developed as an effective alternative in the determination of imidacloprid in honey samples. The peak current variation obtained with the proposed sensor, in the presence of imidacloprid, was higher compared to the bare GCE. The followed experimental conditions were optimized: reduced graphene oxide concentration (2.0 mg mL^?1), manganese (II) phthalocyanine concentration (1.5 mg mL^?1), electrolyte pH (6.5) and electrolyte concentration (1,50 mol L^?1). The study also showed that the process of reduction of imidacloprid is irreversible and diffusion‐controlled, with a single reduction peak of approximately ?0.9 V corresponding to the reduction of the nitro group (?NO2) present in the structure, generating a derived from hydroxylamine, in a process involving about four electrons. The determination of imidacloprid in honey samples exhibited recovery values within the EPA range (between 90.5 and 101.9 %). The proposed sensor GCE/rGO/MnPc can be used as an effective alternative in the determination of imidacloprid in honey samples.     

Square-wave adsorptive stripping voltammetric approaches at two in situ modified electrodes as first analytical methods for the quantitative determination of a new anticancer drug candidate

The two adsorptive stripping voltammetric approaches for detection and quantitative determination of diethyl (2E)-2-{(2E)-[1-(4-methylphenyl)imidazolidin-2-ylidene]hydrazinylidene}butanedioate (DIB)—a novel molecule of medical importance—using two sensitive sensors based on modified glassy carbon electrodes as reusable sensors, were developed for the first time. The proposed electrochemical methods are based on adsorptive/reductive behaviour of DIB at two modified carbonic electrodes: a bismuth film-modified glassy carbon electrode (BiF/GCE) and a lead film-modified glassy carbon electrode (PbF/GCE). The electron gain mechanism for the electrochemical reduction of DIB on both developed sensors was proposed for the first time. To achieve the highest sensitivity in adsorptive stripping determinations, various experimental variables (e.g. the composition and pH of the supporting electrolytes, deposition conditions of bismuth and lead films, concentrations of plating solutions, accumulation times and potentials of DIB, etc.) were extensively examined. The comparison of validation parameters obtained during the determination of DIB at two sensors was presented. The excellent linear correlation was found between the monitored adsorptive stripping voltammetric peak current and the DIB concentration in the range of 15–600 μg L⁻¹ at an accumulation time of 30 s (with LOD = 4.2 μg L⁻¹ and LOQ = 14.0 μg L⁻¹) using the BiF/GCE as a sensor. Furthermore, the excellent linear relationship was confirmed between the monitored adsorptive stripping voltammetric peak current and the DIB concentration in the range of 9–900 μg L⁻¹ at an accumulation time of 10 s (with better LOD = 1.5 μg L⁻¹ and LOQ = 5.0 μg L⁻¹), employing the PbF/GCE as a sensor. The two optimized adsorptive stripping voltammetric approaches—as facile, sensitive, reliable and inexpensive—were successfully used as first methods for the quantitative analysis of a novel anticancer agent (DIB) in its pure pharmaceutically acceptable form. However, the practical applicability of square-wave adsorptive stripping voltammetric determination of the electroactive DIB molecule at a PbF/GCE, as the modified electrode of higher sensitivity, was presented after its successful solid phase extraction from a real serum sample.

     

A new Approach for the Voltammetric Sensing of the Phytoestrogen Genistein at a Non-modified Boron-doped Diamond Electrode

An effective electrochemical sensor was constructed using an unmodified boron-doped diamond electrode for determination of genistein by square-wave voltammetry. Cyclic voltammetric investigations of genistein with HClO₄ solution indicated that irreversible behavior, adsorption-controlled and well-defined two oxidation peaks at about +0.92 (P_A1) & +1.27 V (P_A2). pH, as well as supporting electrolytes, are important in genistein oxidations. Quantification analyses of genistein were conducted using its two oxidation peaks. Using optimized experiments as well as instrumental conditions, the current response with genistein was proportionately linear in the concentrations range of 0.1 to 50.0 μg mL⁻¹ (3.7×10⁻⁷−1.9×10⁻⁴ mol L⁻¹), by the detection limit of 0.023 μg mL⁻¹ (8.5×10⁻⁸ mol L⁻¹) for P_A1 and 0.028 μg mL⁻¹ (1.1×10⁻⁷ mol L⁻¹) for P_A2 in 0.1 mol L⁻¹ HClO₄ solution (in the open circuit condition at 30 s accumulation time). Ultimately, the developed method was effectively applied to detect genistein in model human urine samples by using its second oxidation peak (P_A2).     

Sensitive Voltammetric Determination of Bisphenol A Based on a Glassy Carbon Electrode Modified with Copper Oxide‐Zinc Oxide Decorated on Graphene Oxide

A highly sensitive and selective chemical sensor was prepared based on metallic copper‐copper oxides and zinc oxide decorated graphene oxide modified glassy carbon electrode (Cu?Zn/GO/GCE) through an easily electrochemical method for the quantification of bisphenol A (BPA). The composite electrode was characterized via scanning electron microscopy (SEM), X‐Ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of BPA in Britton‐Robinson (BR) buffer solution (pH 7.1) was examined using cyclic voltammetry (CV). Under optimized conditions, the square wave voltammetry (SWV) response of Cu?Zn/GO/GCE towards BPA indicates two linear relationships within concentrations (3.0 nmol L^?1?0.1 μmol L^?1 and 0.35 μmol L^?1?20.0 μmol L^?) and has a low detection limit (0.88 nmol L^?1). The proposed electrochemical sensor based on Cu?Zn/GO/GCE is both time and cost effective, has good reproducibility, high selectivity as well as stability for BPA determination. The developed composite electrode was used to detect BPA in various samples including baby feeding bottle, pacifier, water bottle and food storage container and satisfactory results were obtained with high recoveries.     

N-Doped Carbon Coated TiC Nanofiber Arrays on Ti-6Al-4V for Sensitive Electrochemical Determination of Cr(VI)

A sensitive electrochemical sensor for Cr(VI) detection based on N-doped carbon coated TiC nanofiber arrays (TiC@CNx NFAs) is reported. The abundant electrocatalytic active sites contained CNx shell, highly conducting TiC core, and good electrical contact between the TiC@CNx and underlying Ti alloy endow this electrode with the excellent electrochemical sensing properties. The developed electrochemical sensor shows remarkable determination activity towards Cr(VI) with a high sensitivity of 0.88 μA μM⁻¹ cm⁻², a low detection limit of 4.0 nM (S/N=3), a wide linear range from 0.2 to 24.1 μM, good selectivity and anti-interference property.