Differential Pulse Stripping Voltammetry Research Articles

Sensitive Differential Pulse Stripping Voltammetry of Caffeine in Medicines and Cola Using a Sensor Based on Multi-Walled Carbon Nanotubes and Nafion

Sensitive Differential Pulse Stripping Voltammetry of Caffeine in Medicines and Cola Using a Sensor Based on Multi-Walled Carbon Nanotubes and Nafion

Preparation of nano-sized Pb 2+ imprinted polymer and its application as the chemical interface of an electrochemical sensor for toxic lead determination in different real samples

In this work, a new nano-structured ion imprinted polymer (IIP) was synthesized by copolymerization of methacrylic acid–Pb 2+ complex and ethylene glycol dimethacrylate according to the precipitation polymerization. Methacrylic acid acted as both functional monomer and complexing agent to create selective coordination sites in a cross-linked polymer. A carbon paste electrode modified with IIP-nanoparticles was used for fabrication of a Pb 2+ sensitive electrode. Differential pulse stripping voltammetry method was applied as the determination technique, after open circuit sorption of Pb 2+ on the electrode and its reduction to metallic form. The IIP modified electrode showed a considerably higher response, compared to the electrode embedded with non-imprinted polymer (NIP). This indicated that the suitable recognition sites were created in the IIP structure in the polymerization stage. Various factors, effective on the response behavior of the electrode, were investigated and optimized. The introduced sensor showed a linear range of 1.0 × 10 −9 to 8.1 × 10 −7 M and detection limit of 6.0 × 10 −10 M (S/N = 3). The sensor was successfully applied for the trace lead determination in different samples.

Amperometric proton selective strip-sensors with a microelliptic liquid/gel interface for organophosphate neurotoxins

A novel strip-based disposable amperometric proton sensor that can selectively detect organophosphate neurotoxins ( i.e., paraoxon) is described. The detection methodology is based on measuring the current change involved in the assisted proton transfer by a proton selective ligand ( e.g., ETH 1778) across a microelliptic hole interface between the aqueous and polyvinylchloride-2-nitrophenyloctylether gel phase. The selective detection of paraoxon is achieved by measuring protons released by the specific hydrolysis of paraoxon with the organophosphorus hydrolase enzyme. A two-step process involving the hydrolysis and proton transfer reaction was characterized using cyclic voltammetry and differential pulse stripping voltammetry. A strip-based sensor fabricated using a simple polydimethylsiloxane (PDMS) mold with the resulting device was found to exhibit a linear response over a wide range of paraoxon concentrations (0.5 μM–100 μM) present in aqueous samples. In addition to the excellent detection limit and a wide dynamic range, a superb selectivity in the presence of common interfering agents in agricultural samples is achieved.

Differential pulse stripping voltammetry of moderately hydrophobic ions based on hydrophobic ionic liquid membranes supported on the Ag/AgCl electrode

Differential pulse stripping voltammetry (DPSV) based on the ion transfer across the hydrophobic ionic liquid and an aqueous sample solution has been achieved for the analysis of moderately hydrophobic ions. The ionic liquid membrane was made of the double layers of gelled trioctylmethylammonium bis(nona-fluorobutanesulfonyl)amide ([TOMA +][C 4C 4N −]), a hydrophobic ionic liquid. The first [TOMA +][C 4C 4N −] layer containing trioctylmethylammonium chloride (TOMACl) was in contact with a AgCl layer of a planar Ag/AgCl electrode, and the second [TOMA +][C 4C 4N −] layer without containing TOMACl was in contact with a sample solution. The linearity between the DPSV peak and the concentration of analytes, tetrapropylammonium and tridecafluoroheptanoate, was found between 5 μmol dm −3 and 200 μmol dm −3 of these ions.

A Study on Preparation and Use of Nano Poly Pyrrole and Nano Poly (3,4-Ethylenedioxythiophene) Coated Glassy Carbon Electrode For The Determination of Antihistamine in Pharmaceutical and Urine Sample

Pheniramine maleate (PA), an antihistamine, was determined by Differential Pulse Stripping voltammetry using nano polypyrrole (Ppy) and nano poly(3,4-ethylenedioxythiophene) (PEDOT) modified glassy carbon electrodes. The cyclic voltammetric behavior of pheniramine was studied in aqueous acidic, neutral and alkaline conditions. One well-defined oxidation peak was observed in the cyclic voltammograms at all pHs. The influence of pH, scan rate and concentration revealed irreversible electron transfer and the oxidation was diffusion controlled adsorption. The SEM analysis confirmed good accumulation of PA on the electrode surface. A systematic study of influence of various experimental parameters that affect the stripping voltammetric response was carried out and the maximum peak current conditions were arrived at. Calibration was made under maximum peak current conditions. The range of study was 0.05 to 0.4 μg/mL on Ppy/GCE and 0.025 to 0.4μg/mL on PEDOT/GCE and the lower limit of determination were 0.035μg/mL on Ppy/GCE and 0.016μg/mL on PEDOT/GCE. The suitability of the method for the determination of PA in pharmaceutical preparations and urine samples was also ascertained.

Application of multiway-variate calibration to simultaneous voltammetric determination of three catecholamines.

Three structurally similar catecholamines, adrenaline (AA), dopamine (DA) and noradrenaline (NA), which are neurotransmitters well known for their treatment of neural disorders and many other diseases, were investigated at a glassy carbon electrode (GCE) with the use of differential pulse stripping voltammetry (DPSV). The aim was to develop a simple, rapid and cost effective method of simultaneous analysis of these three substances in typical samples such as human urine. Each analyte showed typical reversible redox behaviour with the use of cyclic voltammetry in aqueous medium in the pH range of 4.0-7.9, and composite voltammograms of the three analytes were found to consist of three significantly overlapping peaks corresponding to the three individual substances. Thus, two- and three-way multi-variate data analysis methods were investigated. These included unfolding methods such as-partial least squares (UPLS), principal component regression (UPCR) and radial basis function-artificial neural networks (URBF-ANN), as well as trilinear models, such as parallel factor analysis (PARAFAC) and N-way PLS (NPLS). The results were compared with those obtained from two-way voltammetric data matrix with the use of conventional models, PLS, PCR and RBF-ANN. It was found that most of the three-way models, such as PARAFAC and UPLS, performed somewhat better than others on the basis of the %RPET (5.6∼5.9) and mean %Recovery (94∼102). The proposed methods were then applied for the determination of human urine samples spiked with the three catecholamines, and the results were satisfactory.

An Amperometric Proton Selective Sensor with an Elliptic Microhole Liquid/Gel Interface for Vitamin-C Quantification

An amperometric ascorbic acid selective sensor utilizing the transfer reaction of proton liberated from the dissociation of ascorbic acid in aqueous solution across an elliptic micro-hole water/ organic gel interface is demonstrated. This redox inactive sensing platform offers an alternative way for the detection of ascorbic acid to avoid a fouling effect which is one of the major concerns in redox based sensing systems. The detection principle is simply measuring the current change with respect to the assisted transfer of protons by a proton selective ionophore (e.g., ETH 1778) across the micro-hole interface between the water and the polyvinylchloride-2-nitrophenyloctylether gel phase. The assisted transfer reaction of protons generated from ascorbic acid across the polarized micro-hole interface was first characterized using cyclic voltammetry. An improved sensitivity for the quantitative analysis of ascorbic acid was achieved using differential pulse stripping voltammetry with a linear response ranging from 1 to 100 µM concentrations of ascorbic acid. As a demonstration, the developed sensor was applied for analyzing the content of vitamin-C in different types of commercial pharmaceutical tablets and syrups, and a satisfactory recovery from these samples were also obtained.

Utilization of heat-dried Pseudomonas aeruginosa biomass for voltammetric determination of Pb(II)

In this research, thermally dried Pseudomonas aeruginosa cells were used as a biological material for the construction of a microbial biosensor. The preparation, optimization and application of the developed microbial biosensor, which analyzed Pb(II), are presented. The method was based on stripping of adsorbed metal ions from the modified electrode surface. Modified carbon paste electrodes were preconcentrated at open circuit, and then electrochemically measured by using cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV) techniques. It was found that the thermally dried cells were capable of adsorbing Pb(II) ions from aqueous solutions and could determine the ions prominently at optimum experimental conditions. Many important parameters to acquire the best electrochemical response were carried out, including effect of different electrolyte solutions, pH, deposition potential, deposition time, ionic strength, preconcentration time, and effect of interference ions. Finally, a calibration graph was obtained with a linear range from 1.0×10(-6) to 2.0×10(-5) M Pb(II) (R(2)=0.9916) and detection limit was found as 6.0×10(-7) M Pb(II) by using 3×S(b)/m formula. Other analytical properties of the developed microbial biosensor were also investigated. The suggested usage format of P. aeruginosa for the determination of Pb(II) does not require complicated immobilization procedure, easy to handle, and not time consuming.

Simultaneous Differential Pulse Adsorptive Stripping Determination of Imipramine and Its Metabolite Desipramine by the PLS‐1 Multivariate Method

AbstractA method, using stripping differential pulse voltammetry, for the simultaneous determination of Imipramine and its metabolite Desipramine is reported. Both compounds produce, at glassy carbon electrode, an electrochemical signal due to an adsorptive‐oxidative process. The voltammograms show a very high overlap degree between IM and DE peaks. The multivariate calibration method PLS‐1 was employed for the simultaneous determination of both compounds. An experimental design together with the response surface methodology has been used to find the optimum experimental conditions. The developed procedure has been utilized in the analysis of fortified human serum samples with good recovery values for each analyte.

Enzymatic deposition of Au nanoparticles on the designed electrode surface and its application in glucose detection

This paper reported the enzymatic deposition of Au nanoparticles (AuNPs) on the designed 3-mercapto-propionic acid/glucose oxidase/chitosan (MPA/GOD/Chit) modified glassy carbon electrode and its application in glucose detection. Chit served as GOD immobilization matrix and interacted with MPA through electrostatic attraction. AuNPs, without nano-seeds presented on the electrode surface, was produced through the glucose oxidase catalyzed oxidation of glucose. The mechanism of production of AuNPs was confirmed to be that enzymatic reaction products H 2O 2 in the solution reduce gold complex to AuNPs. The characterizations of the electrode modified after each assembly step was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy showed the average particle size of the AuNPs is 40 nm with a narrow particle size distribution. The content of AuNPs on the electrode surfaces was measured by differential pulse stripping voltammetry. The electrochemical signals on voltammogram showed a linear increase with the glucose concentration in the range of 0.010–0.12 mM with a detection limit of 4 μM. This provided a method to the determination of glucose.

Development of ultrasensitive surfactants doped poly(3,4-ethylenedioxythiophene)/multiwalled carbon nanotube sensor for the detection of pyrethroids and an organochlorine pesticide

Fabrication of nano size poly(3,4-ethylenedioxythiophene)/multiwalled carbonnanotubes film on a glassy carbon electrode (PEDOT/MWCNT/GCE) in the presence of anionic and cationic surfactants is reported. The modified composite electrodes were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies. SEM studies confirmed the formation of nano size film on the working electrode. Electroanalytical studies were carried out using the above prepared electrode by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV). This electrode exhibited higher sensitivity towards the reduction of cypermethrin (CYP), deltamethrin (DEL), fenvalerate (FEN) falling under pyrethroids family and an organochlorine pesticide dicofol (DCF). In CV, all the selected pesticides were found to exhibit one well-defined irreversible reduction peak at pH 13. Optimum conditions for DPSV were experimentally determined by varying several parameters. The practical application of the newly developed sensor was affirmed by quantification of the selected pesticides in spiked water samples.

An advanced investigation on a new algal sensor determining Pb(II) ions from aqueous media

It has been well documented that heavy metal accumulation in environment is harmful for living organisms at even trace levels. A new voltammetric algal sensor based on Phormidium sp. modification for Pb(II) determination from aqueous solutions was developed, and selectivity of the biomass to Pb(II) was investigated comprehensively. Many important experimental parameters were performed by using electrochemical techniques, including cyclic voltammetry and differential pulse stripping voltammetry. The preconcentrated ions at open circuit were reduced by scanning the potential from −1.5 to 1.5 V and current values obtained were related to the concentration of Pb(II) in the solutions. The best peak values belonging to Pb(II) were achieved at pH 8.0 with 0.05 M Tris–HCl solution. Preconcentration time was selected as 10 min, and the sensor was found in a linear range from 5.0 × 10 −8 M to 2.0 × 10 −5 M Pb(II) (0.01–4.0 mg L −1) with a detection limit of 2.5 × 10 −8 M. Other analytical properties of the developed microbial biosensor were also investigated. According to the Fourier transform infrared attenuated total reflectance (FTIR-ATR) analyses, the possible functional groups involved in Pb(II) accumulation in the Phormidium sp. were defined as carboxyl, sulphoxide and alcoholic groups. A simple chemical modification by formaldehyde both enhanced Pb(II) determination and content of functional groups involving Pb(II) binding. The proposed usage form of Phormidium sp. does not need complicated immobilization procedures and expensive preliminary preparations.

Electrocatalytical Oxidation and Determination of Luteolin at Ionic Liquid Modified Electrode

A glassy carbon electrode modified with hydrophobicity 1-n-butyl-3-methylimidazolium hexafluoro-phosphate([BMIM]PF6 /GCE) was fabricated. In a 0. 2 mol /L phosphate buffer solution( pH 4. 0 ～ 8. 0), cyclic voltammetry and differential pulse stripping voltammetry were used to investigate the electrochemical behavior of luteolin at the modified electrode and a new method for detection of luteolin was established. As a result,an improved response of luteolin at the modified electrode was observed with peak potential shift negatively and increase of peak current. An electrocatalytic quasi-reversible redox process of controlled by absorption was obtained for luteolin on the surface of the modified electrode in a potential range of - 0. 2 ～ 0. 7 V at pH = 7. 0. The charge transfer coefficient( α) and adsorbed amount( Γ) were calculated to be 0. 5 and 4. 6 × 10 -10 mol /cm2,respectively. The anodic current increased linearly with luteolin concentration in a range of 1. 0 × 10 -10 ～ 1. 6 × 10 -8 mol /L with a detection limit of 3. 2 × 10 -11 mol /L,and the recovery is between 98. 7% and 102. 0% . The method is simple,quick,accurate and reliable. It may provide a novel way for flavonoid determination in wild chrysanthemum flower.

Simultaneous voltammetric analysis of tetracycline antibiotics in foods

The new simple, cost effective and well performing differential pulse stripping voltammetry method for the simultaneous determination of antibiotics – oxytetracycline, tetracycline and chlorotetracycline was researched and developed. It depends on the reduction of these compounds at a hanging mercury drop electrode. The samples were extracted from (i) spiked animal feed, and (ii) fresh fish muscle dosed with the drugs. The voltammograms from the drug mixture produced complex, overlapping profiles, and chemometrics methods were applied for calibration modelling. The analytical linear ranges were within 0.02–0.18 μg mL −1 and the corresponding LODs were 3–5 μg L −1 for the three analytes. These values compare well with those from the HPLC and fluorescence methods in the literature. The % relative prediction errors from the verification trials were between 4% and 9% with % Recoveries being 103–107. Also, the % Recoveries of the antibiotics from animal feeds as measured by the new method were comparable with those from the HPLC analysis (85%), i.e. the method is highly competitive, especially as a screening approach.

Experimental Design Optimization of Arsenic Speciation in Groundwater

The optimization of a Differential-Pulse Stripping Voltammetry (DPSV) procedure for arsenic speciation determination, using sodium diethyldithiocarbamate (DDTC-Na) as complexing agent, is described. An experimental design methodology was used to select the optimal experimental conditions. A robust regression method was used for the calibrations under these conditions that eliminate anomalous points. Electroinactive As(V) was reduced to As(III) with sodium thiosulfate prior to determination. The detection limit obtained was 1.95 × 10−9 mol dm−3. This procedure was successfully applied to the determination of arsenic speciation in groundwater.

Enhanced Sensing of Carbendazim, a Fungicide on Functionalized Multiwalled Carbon Nanotube Modified Glassy Carbon Electrode and Its Determination in Real Samples

An electrochemical sensor was developed by modifying a glassy carbon electrode (GCE) with functionalized multiwalled carbon nanotubes (FMWCNTs). The fabricated electrode was used to examine the redox behavior of carbendazim (CAR) in different pH solutions (pH 1.0–13.0). Surface morphology of the modified film was studied by scanning electron microscopy (SEM). An electroanalytical procedure for the determination of CAR was developed by adsorptive differential pulse stripping voltammetry (DPSV) over the range 0.01–5 × 104 µ g L−1. The developed procedure was also validated in real samples such as soil and water samples, and the applicability of the reported method is highly encouraging.

Using of Rhizopus arrhizus as a sensor modifying component for determination of Pb(II) in aqueous media by voltammetry

For the sensitive determination of Pb(II) from aqueous solutions, a new voltammetric biosensor based on carbon paste electrode modified with Rhizopus arrhizus was developed. The preconcentrated ions at open circuit were reduced by using differential pulse stripping voltammetry technique. The obtained current values were related to the concentration of Pb(II) in the solutions. The best results were achieved at pH 7 with 0.01 M Tris–HCl buffer solution applying a preconcentration time of 12 min. The linear range for the biosensor was found to be within 1.0 × 10 −7–1.25 × 10 −5 M, with a detection limit of 0.5 × 10 −8 M. The selectivity of the microbial biosensor was explored by adding interfering heavy metals to accumulation medium one by one, and their matrix effects were also investigated in the model metal solutions. Energy dispersive X-ray spectra analysis were applied to show the specific effect of the fungal biomass on the Pb(II) determination.

The performance of differential pulse stripping voltammetry at micro-liquid–liquid interface arrays

Microporous silicon membranes were recently introduced to create hexagonally-patterned arrays of micro-scale interfaces between two immiscible electrolyte solutions (μITIES). In this report we present a simulation study of the application of differential pulse stripping voltammetry (DPSV) using these μITIES arrays for ion sensing. Simulations showed that the stripping current for ion detection was enhanced by use of relatively deep pores (i.e. a low pore aspect ratio) and a viscous organic phase. These factors decrease the speed of escape of the pre-concentrated ion from the organic side of the ITIES. The stripping current initially increased steeply with pre-concentration time but eventually reached a plateau. Experiments performed using a μITIES array with micropores of radius 26 μm, depth of 100 μm and with a gelified organic phase demonstrated the saturation of the stripping peak with increasing pre-concentration time for the DPSV detection of tetraethylammonium ion. The reasons for the saturations are discussed in terms of diffusion coefficients and depth of the micropores.

Amperometric proton selective sensors utilizing ion transfer reactions across a microhole liquid/gel interface

A new cost-effective amperometric proton selective sensor utilizing a single microhole interface between two immiscible electrolyte solutions (ITIES) is developed. The sensing methodology is based on measuring currents associated with proton transfer across the interface assisted by a proton selective ionophore. The ellipse shaped micro-interface was first fabricated by simple mechanical punching with a sharp needle on a thin PVC film (12 μm thick) commercially available as a food wrapping material. The microhole was then filled up with a gellified polyvinylchloride (PVC)-2-nitrophenyloctylether (NPOE) to create a single microhole liquid/liquid interface. Direct ion transfer reactions across the polarized interface serving as ion sensing platforms were studied using cyclic voltammetry. In order to enhance the selectivity of proton sensing, a proton selective ionophore, octadecyl isonicotinate (ETH1778), was incorporated into the organic gel layer and their electrochemical sensing characteristics were investigated using cyclic voltammetry and differential pulse stripping voltammetry. As an example, we employed the proton selective sensor for the determination of glucose concentrations. The detection scheme involves two steps: (i) protons are first generated by the oxidation of glucose with glucose oxidase in the aqueous phase; and (ii) the current associated with the proton transfer across the interface is then measured for correlating the concentration of glucose.

Poly(2-amino-4-thiazoleacetic acid)/multiwalled carbon nanotubes modified glassy carbon electrodes for the electrochemical detection of copper(II)

Poly(2-amino-4-thiazoleacetic acid)/multiwalled carbon nanotubes modified glassy carbon electrodes obtained by electropolymerization of 2-amino-4-thiazoleacetic acid, were used for the voltammetric determination of copper ions. The voltammetric response of copper ions at poly(2-amino-4-thiazoleacetic acid)/multiwalled carbon nanotubes modified glassy carbon electrodes was evaluated by differential pulse stripping voltammetry. The peak currents were linearly dependent on the concentrations of the copper ions in the range from 7.0 × 10 −7 M to 5.0 × 10 −5 M, with a coefficiency of 0.9987. The detection limit is 5.0 × 10 −10 M calculated for a signal-to-noise ratio of 3 (S/N = 3). And it could be used for the simultaneous determination of copper and cadmium ions. The proposed method was successfully applied to the determination of copper ions in natural water. The concentration of Cu 2+ was calculated to be 2.0 × 10 −5 M by standard addition method. The recovery rate was 94%.