Modified Paste Electrode Research Articles

Enhancing of hydroquinone and catechol oxidation using a graphite and graphene composite polymer modified paste electrode

ABSTRACT An innovative electrochemical redox response of hydroquinone (HQN) and catechol (CCL) was analysed using a bare graphite and graphene composite paste electrode (BGGCPE) and polymerised L-leucine modified graphite and graphene composite paste electrode (LCN-MGGCPE) was successfully developed in 0.2 M phosphate buffer solution (PBS) with pH 6.0 at a 0.1 V/s scan rate. Fabricated electrode using simple and cost-effective method, the polymerised LCN-MGGCPE surface shows more electrochemical activity, sensitivity and selectivity towards the determination for HQN and CCL. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), Differential pulse voltammetry (DPV), and electrochemical impudence spectroscopy (EIS) were utilised as analytical techniques while LCN-MGGCPE and BGGCPE surface characterisation were studied using a scanning electron microscopy (SEM) technique. LCN-MGGCPE exhibited superior electrochemical activity compared to BGGCPE towards the oxidation responses of both HQN and CCL. Additionally, the effect of pH studies, scan rate change for HQN, and concentration change of analyte molecule were examined, with the 0.025 to 0.500 V/s scan rate varied and revealing an adsorption-controlled process. The concentration changes of CVs methods ranged from 0.2 to 320 μM, DPVs ranged from 0.2 to 1100 μM and LSVs ranged from 0.2 to 850 μM, the calculated a limit of detection (LOD) of CV, DPV, and LSV, is 0.020 μM, 0.026 μM, and 0.011 μM and a limit of quantification (LOQ) of 0.068 μM, 0.088 μM, and 0.035 μM. The electrochemically developed LCN-MGGCPE shows good reproducibility, repeatability, stability, sensitivity and simultaneous analysis of analyte molecules were studied. This study presents a promising pathway for the growth of effective sensors for the determination of HQN in medicinal and water sample applications.

Electroanalysis of tert-butylhydroquinone in food products using a paste electrode enlarged with single wall carbon nanotubes as catalyst

In this study, an electrochemical sensor was introduced as a simple and fast electro­analytical tool to monitor and sensing of tert-butylhydroquinone (TBHQ) in food products. The suggested electrochemical sensor is fabricated by modification of paste electrode (PE) by single wall carbon nanotubes (SWCNTs) as nanocatalyst. The oxidation current of TBHQ was improved by about 2.62 times and its oxidation potential was reduced by about 50 mV after using SWCNTs as conductive catalyst on a carbon paste matrix. The oxidation current of TBHQ showed a linear dynamic range of 0.05 to 390 µM in the sensing process using SWCNTs/PE as the electroanalytical sensor. On the other hand, SWCNTs/PE successfully monitored TBHQ with a detection limit of 10 nM at optimum conditions. The real sample analysis data clearly showed a recovery range of 97.2 to 104.3 %, which is very interesting for a new analytical tool in the food-sensing process.

A Nanocomposite Paste Electrode Sensor for Simultaneous Detection of Uric Acid and Bisphenol A Using Zinc Hydroxide Nitrate-Sodium Dodecylsulfate Bispyribac.

The fabrication of a zinc hydroxide nitrate-sodium dodecylsulfate bispyribac modified with multi-walled carbon nanotube (ZHN-SDS-BP/MWCNT) paste electrode for uric acid and bisphenol A detection was presented in this study. Electrochemical impedance spectroscopy, chronocoulometry, square-wave voltammetry, and cyclic voltammetry were all used to examine the electrocatalytic activities of modified paste electrodes. The modified electrode's sensitivity and selectivity have been considered in terms of the composition of the modifier in percentages, the types of supporting electrolytes used, the pH of the electrolyte, and square-wave voltammetry parameters like frequency, pulse size, and step increment. Square-wave voltammetry is performed by applying a small amplitude square-wave voltage to a scanning potential from -0.3 V to +1.0 V, demonstrating a quick response time and high sensitivity. The ZHN-SDS-BP/MWCNT sensor demonstrated a linear range for uric acid and bisphenol A from 5.0 µM to 0.7 mM, with a limit of detection of 0.4 µM and 0.8 µM, respectively, with good reproducibility, repeatability, and stability as well. The modified paste electrode was successfully used in the determination of uric acid and bisphenol A in samples of human urine and lake water.

Electrochemical determination of phosphodiesterase-3 enzyme inhibitor drug Milrinone with nanodiamond modified paste electrode

Milrinone (MIL) is an essential cardiac inotrope drug for cardiovascular disease. In this study, a simple nanosensor based on a nanodiamond carbon paste electrode modified with flower-like ZnO particles was developed to determine MIL electrochemically rapidly and accurately. The flower-like ZnO nanoparticles were synthesized by a simple and cheap sonochemical method. The structure and morphology of the ZnO nanoparticles were investigated by Fourier transform infrared spectrometer and scanning electron microscopy. The electron transfer properties of bare carbon paste electrodes, nD@CPE, CPE/ZnO, and flower-like carbon paste electrodes modified with ZnO and decorated with nanodiamonds (nD@CPE/ZnO) were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was confirmed that the nanosensor, which was electrochemically characterized by EIS and CV, was designed to increase electrical conductivity and facilitate electron transfer upon the modification of CPE with nanomaterials. The electrochemical behavior of MIL on the modified electrode was investigated by differential pulse voltammetry (DPV). Owing to the developed nD@CPE/ZnO nanosensor, the peak current of 10 µM MIL in pH 4.0 BR buffer solution was found to be approximately 19 times higher in DPV compared to bare CPE. Under optimum conditions, the constructed nanosensor offered a linear calibration curve of concentration ranging from 0.2 to 10 µM with the detection limit (LOD) and quantification limit (LOQ) 41 nM and 136 nM, respectively, for MIL in pH 4.0 Britton Robinson buffer solution. The same electrode was used for stability control after 7 days and its current response was found to decrease to 96.7%. The developed method was successfully used for the determination of MIL in human serum and urine samples. The method based on the use of modified nD@CPE/ZnO, showed linearity from 0.6 to 10 µM in serum and 0.8–10 µM in urine. LOD values were found as 128 nM and 176 nM in serum and urine samples, respectively. According to these results, this optimized method showed reasonable sensitivity for the determination of MIL in serum and urine samples.

Determination of Salicylic Acid Using a Highly Sensitive and New Electroanalytical Sensor

Background:A drug sensor (salicylic acid, in this case) was designed and made up of this research. The senor was made by modification of paste electrode (MPE) with CuO-SWCNTs and 1-hexyl-3-methylimidazolium chloride (HMICl). The MPE/CuO-SWCNTs/HMICl showed catalytic activity for the oxidation signal of salicylic acid in phosphate buffer solution.Methods:Electrochemical methods were used as a powerful strategy for the determination of salicylic acid in pharmaceutical samples. Aiming at this goal, carbon paste electrode was amplified with conductive materials and used as a working electrode.Results:The MPE/CuO-SWCNTs/HMICl was used for the determination of salicylic acid in the concentration range of 1.0 nM – 230 µM using differential pulse voltammetric (DPV) method. At pH=7.0, as optimum condition, the MPE/CuOSWCNTs/HMICl displayed a high-quality ability for the determination of salicylic acid in urine, pharmaceutical serum, and water samples.Conclusion:The MPE/CuO-SWCNTs/HMICl was successfully used as a new and high performance working electrode for the determination of salicylic acid at a nanomolar level and in real samples.

Gold nanoparticles anchored graphitized carbon nanofibers ionic liquid electrode for ultrasensitive and selective electrochemical sensing of anticancer drug irinotecan.

Anelectrochemical sensor is describedfor highly sensitive and selective determination of anticancer drug irinitecan (IRT). Gold nanoparticles anchored graphitized carbon nanofibers (Au@GCNFs) was prepared. Au@GCNFs was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray. The combination of high catalytic activity of the nanocomposite Au@GCNFs and the good conductivity ionic liquid [BMIM]PF6 (IL) resulted ina modified paste electrode (IL/Au@GCNFs-PE). The IL/Au@GCNFs-PE exhibits excellent electrocatalytic activity for selective determination of IRT in the presence of physiological electroactive species, such as ascorbic acid (AA), dopamine (DA), uric acid (UA), and caffeine (CAF) mixture, typically at working potential of 0.88V vs. Ag/AgCl. The linear response ranges 4.0nM-1.79μM and 4.5nM-1.57μM with limits of detection of1.55nM and 1.70nM were calculated for IRT in the absence and presence of the quaternary mixture, respectively. The sensor is reproducible and stable over four weeks, and interference by biologically essential compounds is negligible. The method was applied to the determination of IRT in pharmaceutical formulations, in spiked blood serum and urine, and in clinical patient blood. The recovery values ranged from 96.0 to 104.2%. Graphical abstract The combination of high catalytic activity of the new nanocomposite AuNPs@GCNFs with the good conductivity ionic liquid (IL) resulted to a modified paste electrode (IL/Au@GCNFs-PE). The novel sensor was successfully applied for the sensitive and selective detection of IRT in biological samples in the presence of quaternary ascorbic acid (AA), dopamine (DA), uric acid (UA), and caffeine (CAF) mixture.

Voltammetric Determination of Ophthalmic Drug Dexamethasone Using Poly-glycine Multi Walled Carbon Nanotubes Modified Paste Electrode

Background: Dexamethasone has been used in ophthalmology for the treatment of different eye diseases and it is a powerful synthetic member of the glucocorticoid class of steroid medicament having anti-inflammatory and immunosuppressant characteristics. The aim of this study is to develop a rapid, sensitive and selective voltammetric method for its determination using polygylcine-multi walled carbon nanotubes (polyglycine-MWCNTs) modified paste electrode. Methods: The electro-activity and the voltammetric behavior of dexamethasone on the polyglycine- MWCNTs electrode were deduced by cyclic voltammetry (CV), square wave stripping voltammetry (SWSV), differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV). The method permits accurate and sensitive detection of the ophthalmic drug dexamethasone in the presence of ascorbic acid, dopamine and uric acid from the generated anodic peaks at +950 mV, +740 mV and +700 mV, respectively. Results: The cyclic voltammetric study indicates that dexamethasone created a single anodic peak at about +1100 mV in pH 3 B-R solution and none of the cathodic peak appeared in the subsequent reverse scan. The detection and quantification limits measured for LSV were 0.087 mg/L and 0.29 mg/L, respectively. The extent of recoveries in the presence of equal amounts (1:1 mass ratio) of ascorbic acid, dopamine and uric acid were calculated as 98.28 ± 0.45, 94.46 ± 1.77 and 98.57 ± 0.60%, respectively. The voltammetric procedure was also applied to dexamethasone spiked urine samples(5.0 mg/L) and the percent recovery was determined as 95.2% with the relative standard deviations of 3.29%. Conclusion: Sensitive and selective voltammetric method was proposed for the direct determination of dexamethasone. The modified polyglycine-MWCNTs paste electrode enabled the direct determination of dexamethasone in the presence of biological molecules such as ascorbic acid, dopamine and uric acid. Keywords: Dexamethasone, ophthalmic drug, modified electrode, voltammetry, determination, carbon nanotubes.

Development of an Electrochemical Sensor Based on Covalent Molecular Imprinting for Selective Determination of Bisphenol‐A

AbstractIn this study, an electrochemical sensor was developed and used for selective determination of bisfenol‐A (BPA) by integrating sol‐gel technique and multi‐walled carbon nanotubes (MWCNTs) modified paste electrode. BPA bounded by covalently to isocyanatopropyl‐triethoxy silane (ICPTS) was synthesized as a new precursor (BPA‐ICPTS) and then BPA‐imprinted polymer (BPA‐IP) sol‐gel was prepared by using tetramethoxysilane (TMOS) and BPA‐ICPTS. Non‐imprinted polymer (NIP) sol‐gel was obtained by using TMOS and (3‐Aminopropyl) triethoxysilane. Both BPA‐IP and NIP sol‐gels were characterized by nitrogen adsorption‐desorption analysis, FTIR, SEM, particle size analyzer and optical microscope. Carbon paste sensor electrode was fabricated by mixing the newly synthesized BPA‐IP with MWCNTs, graphite powder and paraffin oil. The electrochemical characterization of the sensor electrode was achieved with cyclic and differential pulse voltammetric techniques. The response of the developed sensor under the most proper conditions was linear in BPA concentration range from 4.0×10−9 to 1.0×10−7 mol L−1 and 5.0×10−7 to 5.0×10−5 mol L−1 and the detection limit was 4.4×10−9 mol L−1. The results unclosed that the proposed sensor displayed high sensitivity and selectivity, superior electrochemical performance and rapid response to BPA.

Photo catalytic applications of gold nanoparticles synthesized by green route and electrochemical degradation of phenolic Azo dyes using AuNPs/GC as modified paste electrode

A highly efficient, quick and environmentally benign protocol has been adopted to synthesize AuNPs using the plant extract of Sueda fruciotosa. UV–vis spectroscopy, XRD, HRTEM, SEM and FTIR were used to characterize the prepared AuNPs. Different concentrations of plant extract were used to optimize the size, morphology and distribution of AuNPs. AuNPs were of small size and spheroid in shape at lower concentration. AuNPs showed a surface plasmon resonance at 443 nm. According to HRTEM the average size of AuNPs was 6–8 nm. The AuNPs were appraised for their photo degradation activity on methylene blue (MB) as an experimental substrate. Photo-catalytic activity of AuNPs was found to be dependent on the concentration of catalyst, irradiation time, size and aggregation of AuNPs. Furthermore, AuNPs exhibited an excellent electro-catalytic activity. The sensitivity of modified AuNPs was also studied for phenolic Azo dyes (PAD) which showed its good degradation activity. These gold nanoparticles found to be significantly applicable in the field of electrochemistry, sensors, catalysis, nano-devices, treatment of waste water and conversion of toxic agents into less toxic compound.

Iron Nanoparticles Coated with Nanostructured Carbon: Synthesis and Application in Glucose Biosensors

Nanowires of carbon coated ferric oxide (Fe2O3/C) have been studied to be applied at an electrochemical glucose biosensor as a new type of carbon paste electrode (CPE) modifier. The Fe2O3/C was synthesized by adapting co-precipitation hydrothermal route. Firstly, amperometric sensor based on a modified CPE doped with Fe2O3 has been developed and compared with CPE doped with Fe2O3/C for hydrogen peroxide (H2O2) determination. The performance evaluations for the modified materials and sensors were studied in detail through cyclic voltammetry (CV) method. After, the electrochemical sensor performance was also evaluated for glucose oxidase (GOx) response biosensor due to considerable interest in the blood sugar control. The results demonstrate that the GOx retains its biocatalytic activity toward the oxidation of glucose and that the bioelectrode modified by the Fe2O3/C matrix has potential for use in biosensors and other bioelectronics devices.

Electrochemical Sensor Based on Multiwall Carbon Nanotube-Paste Electrode for Determination of Promethazine in Pharmaceutical Formulations and Blood Plasma

A multi-walled carbon nanotube modified paste electrode (MWCN-PE) was used for determination of promethazine (PMZ) in drug formulations and blood plasma by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Results revealed that the MWCN-PE shows an electrocatalytic activity toward the anodic oxidation of PMZ by a marked enhancement in the current response in buffered solution at pH 5.0. At the MWCN/CPE, the anodic peak potential of PMZ was shifted by 28.0 mV to more negative potential in comparison with bare carbon paste electrode. The detection limit for this method was 0.025 µmol L-1. Results indicated that the modified electrode could be employed for the determination of promethazine hydrochloride in pharmaceutical formulations and plasma samples.

Voltammetric determination of silver with a new multi-walled carbon nanotube modified paste electrode

This study introduces the sensitive determination of silver using modified carbon paste electrode based on multi-walled carbon nanotubes and a new synthesized chelating agent of N-(4-{4-[(anilinocarbothioyl)amino]benzyl}phenyl)-N-phenylthiourea. This electrochemical method is based on accumulation of silver ions at the surface of a new multi-walled carbon nanotube modified paste electrode. After preconcentration, the measurements were carried out in a closed circuit by electrolysis of the accumulated Ag(I) ions by voltammetric scanning from −0.2 to +0.2 V. Under the optimized conditions, a linear response range from 0.5 to 270 ng mL−1 was obtained. The detection limit and relative standard deviation for seven replicate measurements were 0.079 ng mL−1 and ±2.4%, respectively. The procedure was applied to determination of silver(I) in water, tea leaves and a certified reference material with satisfactory results.

Multiwall Carbon Nanotube‐Ionic Liquid Modified Paste Electrode as an Efficient Sensor for the Determination of Diazepam and Oxazepam in Real Samples

AbstractA carbon‐based electrode using multiwall carbon nanotube as a modifier and room temperature ionic liquid as a binder has been applied for the determination of diazepam (DZP) and oxazepam (OZP) in real samples including serum, urine and tablets. Square wave voltammetry as an appropriate electrochemical technique was applied to achieve improved limits of detection and higher sensitivities. The electrochemical studies were investigated under various experimental conditions such as pH, buffer concentration, ionic strength, deposition potential, deposition time and scan rate to achieve higher sensitivities. Linear concentration ranges for DZP and OZP were 0.02–0.76 mg L−1 and 0.05–1.90 mg L−1 with the detection limits of 4.1 µg L−1 and 5.8 µg L−1, respectively. The proposed method was successfully applied for the analysis of commercially available tablets as well as serum and urine samples and satisfactory results were obtained.

Electrochemical determination of homocysteine using carbon nanotubes modified paste electrode and isoprenaline as a mediator

Homocysteine (HCy) is an important amino acid containing thiol group and is known as a risk factor in relation to ischemic heart disease and stroke. In this study the electrochemical determination of homocysteine (HCy) has been described using isoprenaline hydrochloride (ISP) as a mediator on multiwall carbon nanotubes modified paste electrode (MWCNTPE). Electrochemical behavior of homocysteine was investigated by cyclic voltarrtmetry and chronoamperometry. The cyclic voltammograms showed that the electrocatalytic oxidation of homocysteine occurs in the presence of ISP on the surface of MWCNTPE at a potential about 640 mV. Also, results showed that the oxidatation peak current of HCy at the modified carbon nanotubes electrode was more than unmodified electrode. The diffusion coefficient and the kinetic parameters including electron transfer coefficient and rate constant of electrocatalytic reaction were determined using electrochemical approaches. Linear sweep voltammetry results showed that electrocatalytic oxidation peak current of HCy had linear dynamic range in the range of 5.0 to 800 μmol L−1 with a detection limit of 3.3 μmol L−1 in pH 3.5 (universal buffer).

Electrocatalytic oxidation and determination of homocysteine at carbon nanotubes modified paste electrode using dopamine as a mediator

A carbon paste electrode modified with multiwall carbon nanotubes (MWCNTPE) was prepared to study the electrocatalytic activity of dopamine (DP) in the presence of homocysteine (HCy) and it was used for determination of HCy. The diffusion coefficient of HCy (D = 6.79×10−6 cm2 s−1), and the kinetic parameters of its oxidation such as electron transfer coefficient (α = 0.46), and rate constant (kh = 7.44×102 dm3 mol-1 s-1) were also determined using electrochemical approaches. Under the optimum pH of 5.0, the peak current of oxidation of HCy at MWCNTPE in the presence of DP occurs at a potential about 530 mV and the results showed that the oxidation peak current of HCy at the modified carbon nanotubes electrode was higher than on unmodified electrode. The peak current of differential pulse voltammograms of HCy solutions increased linearly in the range of 3.0-600.0 μM HCy with the detection limit of 2.08 μM HCy. This method was also examined for determination of HCy in physiological serum and urine samples.

Determination of ascorbic acid by a modified multiwall carbon nanotube paste electrode using cetrimonium iodide/iodine

A new modified graphite-multiwall carbon nanotube paste electrode for the determination of ascorbic acid (AA) based on cetrimonium iodide-iodine is described. The electrochemical response characteristics of the modified electrode toward AA were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in phosphate buffer solution (pH 2.0). When compared to activated carbon, graphite, and multiwall carbon nanotube paste electrode containing new modifier, the proposed modified paste electrode not only shifted the oxidation potential of AA towards less positive potential but also enhanced its oxidation peak current. Further, the oxidation of AA was highly stable at the modified paste electrode. The optimum analytical conditions were sought. The current response of AA increases linearly while increasing its concentration from 5.6 \times 10^{-5} to 1.2 \times 10^{-2} M with the correlation coefficient of 0.999 and a detection limit (3\sigma) was found to be 1.2 \times 10^{-6} M. The present modified paste electrode was also successfully used for the determination of AA in the presence of common interference compounds. The present modified electrode was successfully used in the determination of AA in pharmaceutical and food samples.

Preparation of Tetraheptylammonium Iodide-Iodine Graphite-Multiwall Carbon Nanotube Paste Electrode: Electrocatalytic Determination of Ascorbic Acid in Pharmaceuticals and Foods

The present work describes the construction of a new modified graphite-multiwall carbon nanotube paste electrode by casting the appropriate mixture of tetraheptylammonium iodide-iodine as a new modifier. The modified paste electrode was used for the determination of ascorbic acid (AA) in a phosphate buffer solution (pH 2.0). When compared to activated carbon, a graphite and multiwall carbon nanotube paste electrode containing a new modifier, the proposed modified paste electrode not only shifted the oxidation potential of AA towards a less-positive potential but also enhanced its oxidation peak current. Further, the oxidation of AA was highly stable at the modified paste electrode. The optimum analytical conditions were sought. The current response of AA increases linearly while increasing its concentration from 5.6 × 10(-5) to 1.2 × 10(-2) M with a correlation coefficient of 0.9991; the detection limit (3σ) was found to be of 3.6 × 10(-5) M. The present modified paste electrode was also successfully used for the determination of AA in the presence of common interference compounds. The present modified electrode was successfully demonstrated towards the determination of AA in pharmaceutical and food samples.

Electrochemical Behavior of Nitrochlorobenzene Isomers Based on Ordered Porous Silica Carbon Paste Electrode

Several ordered porous materials with representative well-regulated size and cavum structure was synthesized, such as HMS, MCM-41, MCM-48, SBA-15. The ordered porous materials modified carbon paste electrodes were fabricated and well-characterized. The voltammetry behavior of ferrocene at modified paste electrode was investigated. The voltammetry behavior of nitrochlorobenzene isomers at the modified carbon paste electrode was studied respectively. The differences in adsorption of nitrochlorobenzene isomers at these electrodes interface were investigated respectively in electrochemical methods, and the corresponding determination methods were established successfully. Under the optimal condition, o-, m-, p-chloronitrobenzene had a clear reduction peak current. The obvious voltammetric peak showed a linear relationship with the concentration of chloronitrobezene range. The constructed electrode showed excellent reproducibility and stability. The CVs at MCM-41/CPE show clear difference between the three isomers. Based on the difference of their electrochemical behavior, the system for the electrochemical detection of nitrochlorobenzene would be established. The high sensitivity, the good selectivity, the satisfactory repeatability make the method full of practical value. The theory meaning of this research to discuss the electrochemical reaction mechanism of chloronitrobenzene isomers was great.

Potentiometric stripping analysis of bismuth based on carbon paste electrode modified with cryptand [2.2.1] and multiwalled carbon nanotubes

An electrochemical method based on potentiometric stripping analysis (PSA) employing a cryptand [2.2.1] (CRY) and carbon nanotube (CNT) modified paste electrode (CRY–CNT-PE) has been proposed for the subnanomolar determination of bismuth. The characterization of the electrode surface has been carried out by means of scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC). It was observed that by employing CRY–CNT-PE, a 9-fold enhancement in the PSA signal ( dt/ dE) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, dt/ dE (s/V) was proportional to the Bi(III) concentration in the range of 5.55 × 10 −8 to 9.79 × 10 −11 M ( r = 0.9990) with the detection limit (S/N = 3) of 3.17 × 10 −11 M. The practical analytical utilities of the modified electrode were demonstrated by the determination of bismuth in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. Moreover, the results obtained for bismuth analysis in commercial and real samples using CRY–CNT-PE and those obtained by atomic absorption spectroscopy (AAS) are in agreement at the 95% confidence level.

Electrocatalytic oxidation and sensitive detection of deferoxamine on nanoparticles of Fe2O3@NaCo[Fe(CN)6]-modified paste electrode

Electrocatalytic oxidation of deferoxamine was studied on carbon paste electrodes modified with nanoparticles of iron(III) oxide core-cobalt hexacyanoferrate-shell using cyclic voltammetry and chronoamperometry. Voltammetric curves represented two quasi-reversible redox transitions which in the presence of deferoxamine, the two anodic peak currents increased, followed by decreases in the corresponding cathodic currents. This indicated that deferoxamine was oxidized on the immobilized cobalt hexacyanoferrate via two electrocatalytic steps. The rate constants, the electron transfer coefficients and the diffusion coefficient involved in the electrocatalytic oxidation of deferoxamine were reported. A sensitive and time-saving determination procedure was developed for the analysis of the drug in both batch and flow systems, and the corresponding analytical parameters were reported. The proposed amperometric method was also successfully applied to the direct assays of spiked human serum with iron–drug complex.