Voltammetric Determination of Rutin Using a Carbon Composite Electrode Modified with Copper(II)-Resin

Abstract

The preparation and electrochemical characterization of a carbon composite electrode modified with copper(II)-resin as well as its behavior toward rutin were investigated using cyclic and linear sweep voltammetry. The best voltammetric response was observed for a composite composition of 20% (m/m) copper(II)-resin, 0.10 mol L^?1 KNO₃/10^?6 mol L^?1 HNO₃ solution (pH 6.0) as the supporting electrolyte, and a scan rate of 50 mVs^?1. A linear voltammetric response for rutin was obtained in the concentration range from 9.90 × 10^?7 to 8.07 × 10^?6 mol L^?1, with a detection limit of 2.65 × 10^?8 mol L^?1. The proposed electrode was useful for the quality control and routine analysis of rutin in pharmaceutical formulations.     

Correlation between Electrochemical Impedance and Spectroscopic Measurements in Adsorbing Paraquat on Silver: Application in Underground Water Samples

The electrochemical impedance spectroscopy (EIS) has been used to study the interaction between paraquat and carbon modified by silver (Ag? CPE) and silver particles‐impregnated natural phosphate (Ag/NPh? CPE). This study was developed using spectrophotometry (UV? Vis) and infrared spectroscopy. The resulting interaction was controlled by adsorption at lower concentration (≤1.0×10^?5 mol L^?1) and by diffusion in the opposite case. Both electrodes are used to determining paraquat with a low detection limit (<1.0×10^?12 mol L^?1). The precision expressed as relative standard deviation RSD for the concentration level 1.0×10^?5 mol L^?1 of paraquat, (n=8) were 0.93 % and 1.1 % for Ag/NPh? CPE and Ag? CPE respectively.     

Determination of Rutin in Green Tea Infusions Using Square‐Wave Voltammetry with a Rigid Carbon‐Polyurethane Composite Electrode

This paper presents a comparative study on the electrochemical behavior of the flavonoid rutin on a rigid carbon‐polyurethane composite electrode and on a glassy carbon electrode. The electrochemical oxidation reaction of rutin was found to be quasireversible and affected by adsorption on the electrode surface. A square‐wave voltammetric method was developed for determination of rutin in green tea infusion samples using the RCPE electrode and data treatment by a deconvolution procedure. The detection limit achieved in buffered solutions was 7.1×10^?9 mol L^?1 using the RCPE and 1.7×10^?8 mol L^?1 using the GC electrode the average reproducibility for five determinations being 3.5%.     

A novel sensor based on multi-walled carbon nanotubes and boron-doped double-layer molecularly imprinted membrane for the analysis of SCZ in pharmaceutical and biological samples

ABSTRACT

A molecularly imprinted electrochemical sensor for the rapid detection of the anti-parasitic drug Secnidazole (SCZ) is reported. In this work, the build electrochemical sensor was based on a carbon paste electrode (CPE) modified with multi-wall carbon nanotubes (MWCNTs) and boron-embedded duplex molecularly imprinted composite membranes (B-DMICMs), that significantly increased the efficiency of the sensor for the detection of template molecule SCZ. Density functional theory (DFT) was employed to study the interactions between the template and monomers to select appropriate functional monomers for rational design of the B-DMICMs.The optimal experimental conditions were optimised for the factors affecting the performance of the sensor. Under the optimal conditions, the reduction peak currents of SCZ by differential pulse voltammetry increased linearly with SCZ concentration in the range from 3.0 × 10^?4 to 1.0 × 1.0^?6 mol L^?1 and 1.0 × 1.0^?6 to 1.91 × 10^?8 mol L^?1 with a detection limit of 1.72 × 10^?8 mol L^?1 for secnidazole, which is significantly lower than those in the currently used methods and in previous reports. This method offers low cost, sensitive and effective determination of SCZ and can potentially be used for detection of SCZ in pharmaceutical and biological samples with good precision and accuracy.     

Direct Electroanalytical Determination of Fluvastatin in a Pharmaceutical Dosage Form: Batch and Flow Analysis

Abstract

The reduction of luvastatin (FLV) at a hanging mercury-drop electrode (HMDE) was studied by square-wave adsorptive-stripping voltammetry (SWAdSV). FLV can be accumulated and reduced at the electrode, with a maximum peak current intensity at a potential of approximately ?1.26 V vs. AgCl/Ag, in an aqueous electrolyte solution of pH 5.25. The method shows linearity between peak current intensity and FLV concentration between 1.0 × 10^?8 and 2.7 × 10^?6 mol L^?1. Limits of detection (LOD) and quantification (LOQ) were found to be 9.9 × 10^?9 mol L^?1 and 3.3 × 10^?8 mol L^?1, respectively.

Furthermore, FLV oxidation at a glassy carbon electrode surface was used for its hydrodynamic monitoring by amperometric detection in a flow-injection system. The amperometric signal was linear with FLV concentration over the range 1.0 × 10^?6 to 1.0 × 10^?5 mol L^?1, with an LOD of 2.4 × 10^?7 mol L^?1 and an LOQ of 8.0 × 10^?7 mol L^?1. A sample rate of 50 injections per hour was achieved.

Both methods were validated and showed to be precise and accurate, being satisfactorily applied to the determination of FLV in a commercial pharmaceutical.     

Electrochemical Behaviors of Adenosine‐5′‐triphosphate on Molecular Wire Modified Carbon Paste Electrode and Its Sensitive Detection

A new electrochemical method was proposed for the determination of adenosine‐5′‐triphosphate (ATP) based on the electrooxidation at a molecular wire (MW) modified carbon paste electrode (CPE), which was fabricated with diphenylacetylene (DPA) as the binder. A single well‐defined irreversible oxidation peak of ATP appeared on MW‐CPE with adsorption‐controlled process and enhanced electrochemical response in a pH 3.0 Britton‐Robinson buffer solution, which was due to the presence of high conductive DPA in the electrode. The electrochemical parameters of ATP were calculated with the electron transfer coefficient (α) as 0.54, the electron transfer number (n) as 1.9, the apparent heterogeneous electron transfer rate constant (k_s) as 2.67 × 10^?5 s^?1 and the surface coverage (Γ_T) as 4.15 × 10^?10 mol cm^?2. Under the selected conditions the oxidation peak current was proportional to ATP concentration in the range from 1.0 × 10^?7 mol L^?1 to 2.0 × 10^?3 mol L^?1 with the detection limit as 1.28 × 10^?8 mol L^?1 (3σ) by sensitive differential pulse voltammetry. The proposed method showed good selectivity without the interferences of coexisting substances and was successful applied to the ATP injection samples detection.     

A novel and simple biosensor based on poly(indoleacetic acid) film and its application for simultaneous electrochemical determination of dopamine and epinephrine in the presence of ascorbic acid

A novel and simple biosensor based on poly(indoleacetic acid) film-modified electrode (PIAA/CPE) was fabricated by electrochemical polymerization of indoleacetic acid on a carbon paste electrode (CPE) through cyclic voltammetry. The resulting electrode was characterized by scanning electron microscopy, and the electrochemical behaviors of dopamine (DA) and epinephrine (EP) at the electrode were studied. It was illustrated that PIAA/CPE had excellent electrochemical catalytic activities toward DA and EP. The anodic peak currents (I _pa) were dramatically enhanced by about seven-fold for DA and ten times for EP at PIAA/CPE. Thus, the determinations of DA and EP were carried out using PIAA/CPE successfully. The linear responses were obtained in the range of 3.0?×?10^?7～7.0?×?10^?4 and 1.0?×?10^?6 ～8.0?×?10^?4 mol L^?1 with the detection limits (3σ) of 1?×?10^?7 and 4?×?10^?7 mol L^?1 corresponding with DA and EP, respectively. Moreover, the cathodic peaks of DA and EP were well-separated with a potential difference about 325 mV in pH 5.3 phosphate-buffered saline, so simultaneous determination of DA and EP was carried out in this paper. Additionally, the interference studies showed that the PIAA/CPE exhibited excellent selectivity in the presence of ascorbic acid (AA). With good selectivity and sensitivity, the present method has been successfully applied to the determination of DA and EP in pharmaceutical samples.     

Detection of rutin at DNA modified carbon paste electrode based on a mixture of ionic liquid and paraffin oil as a binder

A DNA-modified carbon paste electrode (DNA-CPIE) was designed by using a mixture of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate and paraffin oil as the binder. The electrochemistry of rutin at the DNA-CPIE was investigated by cyclic voltammetry and differential pulse voltammetry. Rutin exhibits a pair of reversible redox peaks in buffer solutions of pH 3.0, and respective electrochemical parameters are established. Under the optimal conditions, the oxidative peak current is linear with the concentration of rutin in the range from 8?×?10^?9 to 1?×?10^?5 mol L^?1, and the detection limit is 1.3?×?10^?9 mol L^?1 (at S/N?=?3). The electrode exhibits higher sensitivity compared to DNA modified carbon paste electrode without ionic liquid and better selectivity comparing with electrodes without DNA. It also showed good performance, stability, and therefore represents a viable method for the determination of rutin.     

A simple method for determination of urapidil at a glassy carbon electrode modified with poly(sodium4-styrenesulfonate) functionalized graphene

ABSTRACT

A simple, highly sensitive voltammetric method for the determination of urapidil at poly(sodium4-styrenesulfonate) functionalized graphene-modified electrode (PSS-Gr/GCE) was described. Based on the PSS-Gr composites-modified glassy carbon electrode as a simple voltammetric sensor, it exhibited good conductivity and high sensitivity to urapidil. Under the optimize condition, a good linear relationship was obtained between peak currents and urapidil concentrations in the wider range of 2.0 × 10^?9–8.0 × 10^?8 mol L^?1 and 2.0 × 10^?7–2.0 × 10^?5 mol L^?1 with detection limit of 8 × 10^?10 mol L^?1 (S/N = 3). Based on the high sensitivity and good selectivity of the proposed electrode, the proposed method could apply to the detect of urapidil in urapidil sustained release tablets with satisfactory results.     

Preparation of CuO-Nanoparticle-Modified Electrode and Its Application in the Determination of Rutin

Abstract

In this article, highly pure, well-dispersed, 10-nm CuO nanoparticles were obtained by a hydrothermal reduction process, with oxalic acid as precipitator. The CuO nanoparticles were characterized by x-ray powder diffraction, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. The CuO nanoparticles were modified onto a gold electrode to study the effect on the redox of the rutin. Cyclic voltammetry results show that the CuO nanoparticles were very active for rutin and that the CuO-nanoparticle-modified electrode can even determine rutin in a certain range of concentration from 5.0 × 10^?7 to 5.0 × 10^?4 mol L^?1 by differential pulse voltammertry, which provides a new application for CuO nanoparticles.     

Fluorescence Probe Enhanced Spectrofluorimetric Method for the Determination of Prulifloxacin in Pharmaceutical Formulations and Biological Fluids

Abstract

Spectrofluorimetry for the determination of prulifloxacin (PUFX) was developed based on the strong fluorescence of PUFX after adding fluorescence probe yttrium in buffer solution (pH = 6.80), and various factors of influencing fluorescence have been researched. Under the optimum conditions, the liner range was 2.0 × 10^?8 to 9.1 × 10^?6 mol L^?1 and the detection limit was 8.5 × 10^?9 mol L^?1. The relative standard deviation was 2.1% for 11 measurements of 5.0 × 10^?7 mol L^?1 PUFX standard solution. The mechanism of the sensitizing effect of probe was discussed. The method was applied for the determination of PUFX in actual sample; the result obtained was satisfactory.     

Sensitive Simultaneous Determination of Rutin and Folic Acid with the Use of a Solid Lead Electrode by Means of Adsorptive Stripping Voltammetry

In this article a solid lead electrode (PbE) was utilized for the first time for determination of organic substances by means of adsorptive stripping voltammetry. A new procedure of simultaneous determination of rutin and folic acid was developed. Two well shaped and well separated reduction signals of rutin and folic acid were obtained with the use of PbE. The optimization of analytical procedure was presented. The calibration graphs for rutin and folic acid for an accumulation time of 120 s were linear in the ranges from 2×10^?9 to 1×10^?7 mol L^?1 and from 2×10^?9 to 5×10^?8 mol L^?1, respectively. The obtained detection limits for rutin and folic acid determination following accumulation time of 120 s were 7.9×10^?10 and 8.4×10^?10 mol L^?1. Potential interference effects were investigated. The proposed procedure was used for analysis of pharmaceutical preparations with satisfactory results showing practical applications. The analytical parameters of the proposed procedure were compared with other voltammetric procedures of mentioned substances determination.     

Molecular Imprinting-Chemiluminescence Sensor for the Determination of Prulifloxacin

Abstract

A selective molecular imprinting-chemiluminescence sensor is developed for the determination of prulifloxacin by using a prulifloxacin-imprinted polymer as recognition material and the cerium(IV)/sodium thiosulfate/prulifloxacin chemiluminescence reaction as the detection system. The linear response range of the sensor is from 8.0 × 10^?8 to 7.0 × 10^?6 mol L^?1 with a detection limit of 2.0 × 10^?8 mol L^?1. The relative standard deviation for 5.0 × 10^?7 mol L^?1prulifloxacin solution is 1.3% (n = 7). This sensor has been applied to the determination of prulifloxacin in urine samples, and the results obtained are satisfactory.     

Voltammetric detection of guanosine and adenosine using a carbon paste electrode modified with 1-ethyl-3-methylimidazolium ethylsulfate

A novel kind of carbon paste electrode (CPE) was prepared by mixing graphite powder, liquid paraffin and the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate. The resulting electrode was used for the simultaneous determination of guanosine and adenosine by differential pulse voltammetry. Compared to a conventional CPE, the oxidation peak currents are largely increased, and the oxidation peak potentials are negatively shifted. The electrochemical responses to guanosine and adenosine were investigated. Under optimized conditions, the calibration curves are linear in the concentration range from 1.0?×?10^-6?mol?L^-1 to 1.6?×?10^-4?mol?L^-1 for guanosine, and from 1.0?×?10^-6?mol?L^-1 to 2.7?×?10^-4?mol?L^-1 for adenosine at pH 3.5. Substances potentially interfering in the biological matrix do no interfere. The method was successfully applied to detect adenosine and guanosine in human urine without sample treatments.

Magnetite NPs@C with Highly‐Efficient Peroxidase‐Like Catalytic Activity as an Improved Biosensing Strategy for Selective Glucose Detection

This work reports the novel application of carbon‐coated magnetite nanoparticles (mNPs@C) as catalytic nanomaterial included in a composite electrode material (mNPs@C/CPE) taking advantages of their intrinsic peroxidase‐like activity. The nanostructured electrochemical transducer reveals an enhancement of the charge transfer for redox processes involving hydrogen peroxide. Likewise, mNPs@C/CPE demonstrated to be highly selective even at elevated concentrations of ascorbic acid and uric acid, the usual interferents of blood glucose analysis. Upon these remarkable results, the composite matrix was further modified by the addition of glucose oxidase as biocatalyst, in order to obtain a biosensing strategy (GOx/mNPs@C/CPE) with enhanced properties for the electrochemical detection of glucose. GOx/mNPs@C/CPE exhibit a linear range up to 7.5×10^?3 mol L^?1 glucose, comprising the entirely physiological range and incipient pathological values. The average sensitivity obtained at ?0.100 V was (1.62±0.05)×10⁵ nA L mol^?1 (R²=0.9992), the detection limit was 2.0×10^?6 M while the quantification limit was 6.1×10^?6 mol L^?1. The nanostructured biosensor demonstrated to have an excellent performance for glucose detection in human blood serum even for pathological values.     

Voltammetric Behavior and Determination of Cinnarizine in Pharmaceutical Formulations and Serum

Abstract

The electrochemical reduction of cinnarizine was investigated by cyclic and linear sweep adsorptive voltammetry at glassy carbon electrode in Britton-Robinson buffers over the pH range 2.5–11.5. For analytical purposes, a well-defined adsorption-controlled cathodic peak was obtained at pH 2.5. By cathodic adsorptive linear sweep voltammetry, a linear calibration plot was obtained in the range of 2.0 × 10^?7 to 5.0 × 10^?6 mol L^?1 with detection limit of 9.0 × 10^?9 mol L^?1. The method was successfully applied to the determination of cinnarizine in commercial formulations with mean recovery and relative standard deviation of 100.24% and 1.46, respectively. The proposed method was also applied for drug determination in spiked serum samples by applying the standard addition method with a mean recovery of 97.80% and standard deviation of 3.06.     

Stripping voltammetry method for determination of manganese as complex with oxine at the carbon paste electrode with and without modification with montmorillonite clay

Oxine (8-hydroxyquinoline) was used as an efficient and selective ligand for stripping voltammetry trace determination of Mn(II). A validated square-wave adsorptive cathodic stripping voltammetry method has been developed for determination of Mn(II) selectively as oxine complex using both the bare carbon paste electrode (CPE) and the modified CPE with 7 % (w/w) montmorillonite-Na clay. Modification of carbon paste with montmorillonite clay was found to greatly enhance its adsorption capacity. Limits of detection of 45 ng l^?1 (8.19?×?10^?10 mol L^?1) and 1.8 ng l^?1 (3.28?×?10^?11 mol L^?1) Mn(II) were achieved using the bare and modified CP electrodes, respectively. The achieved limits of detection of Mn(II) as oxine complex using the modified CPE are much sensitive than the detection limits obtained by most of the reported electrochemical methods. The developed stripping voltammetry method using both electrodes was successfully applied for trace determination of Mn(II) in various water samples without interferences from various organic and inorganic species.     

The electrochemical oxidation of pentachlorophenol and its sensitive determination at chitosan modified carbon paste electrode

We report on a novel electrochemical method to detect trace pentachlorophenol (PCP) by using a chitosan (CS) modified carbon paste electrode (CS/CPE). Compared with that at a bare carbon paste electrode (CPE), the current response was greatly improved at the CS/CPE due to the enhancement effect of CS. Under optimal working conditions, the oxidation peak current of PCP was proportional to its concentration in the range of 1.0 × 10^?7 to 5.0 × 10^?6 and 5.0 × 10^?6 to 1.0 × 10^?4 mol/L, with an extremely low detection limit of 4.0 × 10^?8 mol/L. Our method was successfully used to detect the PCP concentration in vegetable samples.     

Flow-Injection Chemiluminescent Determination of Piroxicam Using Tris (2,2′-bipyridyl) Ruthenium(II)—Potassium Permanganate System

Abstract

A rapid and sensitive chemiluminescence method using flow-injection has been developed for the determination of an analgesic agent drug, piroxicam. The method is based on the chemiluminescence reaction of piroxicam with an acidic potassium permanganate and Ru(bipy)₃ ²⁺. The chemiluminescence intensity is greatly enhanced when quinine sulfate is used as a sensitizer. After optimization of the different experimental parameters, a calibration graph was obtained over a concentration range of 3.0 × 0^?8–3.0 × 0^?5 mol L^?1 with the detection limit of 1.0 × 0^?8 mol L^?1. The relative standard deviation is 1.5% (n = 11) for the determination of 8.0 × 10^?7 mol L^?1 piroxicam. The proposed method was successfully applied to commercial tablets, spiked serum, and urine samples.     

Flow Injection Analysis of Maleic Hydrazide Using an Electrochemical Sensor Based on Palladium‐Dispersed Carbon Paste Electrode

A new analytical methodology for the electrochemical detection of the herbicide maleic hydrazide (3,6‐dihydroxypyridazine) by flow injection analysis is presented. This method is supported by the novel application of a palladium‐dispersed carbon paste electrode as an amperometric sensor for this herbicide. Maleic hydrazide shows anodic electrochemical activity on carbon‐based electrodes (glassy carbon or carbon paste electrodes) in all the pH range. This electrochemical activity is enhanced using metal‐dispersed carbon paste electrodes, especially at Pd‐dispersed CPE which displays good oxidation signals at 690 mV (0.050 M phosphate buffer pH 7.0), 140 mV lower than at unmodified electrodes. Under the optimized conditions, the electroanalytical performance of Pd‐dispersed CPE in flow injection analysis was excellent, with good reproducibility (RSD 3.3%) and a wide linear range (1.9×10^?7 to 1.0×10^?4 mol L^?1). A detection limit of 1.4×10^?8 mol L^?1 (0.14 ng maleic hydrazide) was obtained for a sample loop of 100 μL at a fixed potential of 700 mV in 0.050 M phosphate buffer solution at pH 7.0 and a flow rate of 2.0 mL min^?1. The proposed method was applied for the maleic hydrazide detection in natural drinking water samples.