Dopamine In Pharmaceutical Samples Research Articles

Development of an Electrochemical Sensor for Selective Determination of Dopamine Based on Molecularly Imprinted Poly(p‐aminothiophenol) Polymeric Film

AbstractIn this study, a molecularly imprinted electrochemical sensor (MIP/DA) was investigated for selective and sensitive determination of dopamine (DA) by electrochemical polymerization of p‐aminothiophenol in the presence of DA on gold electrode. According to electrochemical behaviour of the sensor, gained through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), MIP/DA sensor showed distinctive electron transfer characteristics in comparison to the non‐imprinted (NIP/DA) sensor. Besides the MIP/DA sensor showed high selectivity for dopamine through its analyte specific cavities. The sensor had a broad working range of 5.0×10−8–2.0×10−7 M with a limit of detection (LOD) of 1.8×10−8 M and the developed sensor was successfully applied for determination of dopamine in pharmaceutical samples.

An electrochemical sensor for sensitive detection of dopamine based on MWCNTs/CeO2-PEDOT composite

In this study, firstly, multi-walled carbon nanotubes (MWCNTs) were electrochemically deposited on a glassy carbon electrode (GCE) and, secondly, this was modified with nanoceria-poly(3,4-ethylenedioxythiophene) (CeO2-PEDOT) composite prepared according to the chemical synthesis process in the presence of sodium dodecylsulfate (SDS). The CeO2-PEDOT composite was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The MWCNTs/CeO2-PEDOT modified electrode was used for the sensitive analysis of dopamine (DA) in the presence of uric acid (UA) and ascorbic acid (AA) for the first time. Compared with a bare GCE, the MWCNTs/CeO2-PEDOT modified GCE exhibited a more effective electrocatalytic performance with regard to the oxidation of DA. Under optimum conditions, the prepared GCE/MWCNTs/CeO2-PEDOT sensor showed two wide linear ranges of 0.10–10 μmol L−1 and 40–400 μmol L−1 with a good detection limit of 0.03 μmol L−1. Important effects of interferences such as Ca2+, K+, Na+, glucose, urea, sucrose, citric acid and cystine were not observed on the differential pulse response of dopamine for the prepared sensor. In addition, the sensor designed as a new platform was successfully utilized for the electrochemical analysis of DA in pharmaceutical samples.

Electrochemical sensor for the detection of dopamine in real samples using polyaniline/NiO, ZnO, and Fe3O4 nanocomposites on glassy carbon electrode

Polyaniline (PANI)-MO (where MO are NiO, ZnO, and Fe3O4 nanoparticles) nanocomposites coating on glassy carbon electrode (GCE) was used for the electrochemical detection of dopamine (DA) in the presence of ascorbic acid (AA) and serotonin (SE). The electrochemical response of dopamine on the modified electrode was determined using differential pulse voltammetry (DPV) at physiological pH 7.0. The dynamic range for the dopamine determination was from 2.0 × 10−5 to 2.4 × 10−6 M with detection limits 0.153 × 10−7, 0.166 × 10−7, and 0.176 × 10−7 M for GCE/PANI-NiO, GCE/PANI-ZnO, and GCE/PANI-Fe3O4 sensors, respectively. The LOD value reveals that the best electrode is GCE/PANI-NiO. The common interfering species such as ascorbic acid and serotonin do not interfere over this range of concentrations which show the selectivity of the proposed sensors. The prepared electrode exhibited satisfactory stability when stored at ambient conditions. It has been demonstrated in this study that the GCE/PANI-MO modified electrode can be successfully used for the assay of dopamine in pharmaceutical samples of dopamine hydrochloride injection.

Electropolymerization of ferulic acid on multi-walled carbon nanotubes modified glassy carbon electrode as a versatile platform for NADH, dopamine and epinephrine separate detection

The polymerization of ferulic acid (poly-FA) on multi-walled carbon nanotubes (MWCNT) modified glassy carbon electrode was performed and the modified platform applied for the determination of NADH, epinephrine (EP) and dopamine (DA), one at a time. Cyclic voltammetry and chronoamperometry were employed to investigate the electrocatalytic oxidation of NADH, EP and DA on the modified electrode, in aqueous solutions. The obtained analytical curves for NADH, EP, and DA showed linear ranges between 59–1560, 73–1406, and 5–120μmolL−1, respectively. The detection limits were 17.7, 22.2 and 2.2μmolL−1 for NADH, EP and DA, respectively. The catalytic constant for the oxidation of NADH, EP and DA on the modified electrode were 5.56×103, 6.99×103 and 1.15×104Lmol−1s−1, respectively. The obtained versatile electrode was applied to the successful determination of EP, in epinephrine hydrochloride injection and DA in pharmaceutical samples.

A biosensor based on gold nanoparticles stabilized in poly(allylamine hydrochloride) and decorated with laccase for determination of dopamine.

Gold nanoparticles stabilized in poly(allylamine hydrochloride) (AuNP-PAH) were used as a support for the immobilization of the enzyme laccase obtained from genetically-modified microorganisms (Aspergillus oryzae) and successfully applied in the development of a new biosensor for the determination of dopamine by square-wave voltammetry. The electrochemical characterization of the biosensor was performed by cyclic voltammetry and electrochemical impedance spectroscopy and indicated that the nanomaterial used for the electrode modification facilitated the electron transfer. Under optimized conditions, the calibration curve showed a linear range for dopamine from 0.49 to 23.0 μmol L(-1), with a limit of detection of 0.26 μmol L(-1). The biosensor demonstrated suitable selectivity and stability, good intra-day and inter-day repeatability and electrode-to-electrode repeatability, with relative standard deviations of 4.95, 4.85 and 4.21%, respectively. The proposed biosensor was successfully applied to the determination of dopamine in pharmaceutical samples and the results were in agreement with those obtained using a spectrophotometric method. The recoveries of 97.6 to 105.5% obtained for the samples demonstrate that the proposed method is suitable for practical applications. The good analytical performance of the proposed method can be attributed to the efficient immobilization of laccase in the nanomaterial and the facilitation of electron transfer between the protein and the electrode surface due to the presence of the Au nanoparticles and the PAH polymer.

Highly selective and sensitive dopamine and uric acid electrochemical sensor fabricated with poly (orotic acid)

A novel dopamine (DA) and uric acid (UA) electrochemical sensor (poly-OA/CPE) was fabricated by electrochemical polymerization of orotic acid (OA) on a carbon paste electrode (CPE). The sensor was characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) and the electrochemical behaviors of DA and UA were investigated. The experimental results illustrated that the sensor has an excellent electrocatalytic activity towards the oxidation of DA and UA. By using differential pulse voltammetry (DPV) method, low detection limits (S/N=3) of 0.08μM and 0.28μM for DA and UA were obtained, with the linear calibration curves over the concentration range of 0.31–15.21μM and 17.71–141.01μM for DA and 0.82–11.32μM and 13.62–200.62μM for UA, respectively. Moreover, the sensor exhibits good selectivity and sensitivity toward simultaneous determination of DA and UA. The practical analytical utility is illustrated by the determination of DA in pharmaceutical samples without any preliminary treatment.

Halloysite clay nanotubes and platinum nanoparticles dispersed in ionic liquid applied in the development of a catecholamine biosensor

Halloysite clay nanotubes were used as a support for the immobilization of the enzyme peroxidase from clover sprouts (Trifolium), and employed together with platinum nanoparticles in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid (Pt-BMI·PF(6)) in the development of a new biosensor for the determination of catecholamines by square-wave voltammetry. Under optimized conditions, the analytical curves showed detection limits of 0.05, 0.06, 0.07, 0.12 μM for dopamine, isoproterenol, dobutamine and epinephrine, respectively. The biosensor demonstrated high sensitivity, good repeatability and reproducibility, and long-term stability (18% decrease in response over 150 days). A recovery study of dopamine in pharmaceutical samples gave values from 97.5 to 101.4%. The proposed biosensor was successfully applied to the determination of dopamine in pharmaceutical samples, with a maximum relative error of ±1.0% in relation to the standard (spectrophotometric) method. The good analytical performance of the proposed method can be attributed to the efficient immobilization of the peroxidase in the nanoclay, and the facilitation of electron transfer between the protein and the electrode surface due to the presence of the Pt nanoparticles and ionic liquid.

Determination of dopamine at the nanogram level based on the formation of Prussian blue nanoparticles by resonance Rayleigh scattering technique

In pH 2.6 HCl solution, dopamine (DA) could reduce Fe(III) to Fe(II), which further reacted with [Fe(CN) 6] 3− to form a Fe 3[Fe(CN) 6] 2 complex. By virtue of hydrophobic force and Van der Waals force, the complex aggregated to form Fe 3[Fe(CN) 6] 2 nanoparticles with the average diameter of about 20 nm. This resulted in a significant enhancement of resonance Rayleigh scattering (RRS). The maximum wavelength of the ion-association complex was located at about 350 nm. The increment of scattering intensity (Δ I RRS) was directly proportional to the concentration of DA in the range of 0.06–1.0 μg/mL. This method has high sensitivity and the detection limit (3 σ) for DA was 3.43 ng/mL. In this work, the characteristics of absorption and RRS spectra of this reaction have been studied. The optimum reaction condition and influencing factors have been investigated. The method was applied to the determination of DA in pharmaceutical samples with satisfactory results. Furthermore, the reaction mechanism and the reasons of RRS enhancement have been explored.

A Biosensor for Sensitive and Selective Determination of Dopamine Based on Poly(methyl red) Film Modified Electrode

Poly (methyl red) film was deposited on a carbon paste electrode (CPE) through cyclic voltammetry (CV) and a novel and simple biosensor (PMR/CPE) for highly sensitive and selective determination of dopamine (DA) was fabricated. The polymer film was characterized by scanning electron microscopy (SEM) and the electrochemical behavior of DA at PMR/CPE was studied. It was illustrated that the polymer film had excellent electrochemical catalytic activity towards DA. The anodic peak current of DA was dramatically enhanced by about four folds at PMR/CPE and the standard rate constant (Ks) for DA could be calculated to be 4.686 s−1. Moreover, the separation of oxidation peak potentials of DA and uric acid (UA) was 140 mV, and no oxidation peak for ascorbic acid (AA) appeared at PMR/CPE. Thus, the sensitive and selective determination of DA was carried out successfully. The linear response was obtained over two concentration internals: 1.00 × 10−8∼1.00 × 10−7 mol L−1 and1.00 × 10−7∼1.00× 10−3 mol L−1 with a low detection limit (S/N = 3) of 5 × 10−9 mol L−1. With favorable selectivity and sensitivity, the present method has been successfully applied to the determination of DA in pharmaceutical samples.

Novel and sensitive methods for the determination of dopamine based on the resonance Rayleigh scattering, second-order scattering and frequency doubling scattering quenching effects

Three novel methods were designed for the determination of dopamine (DA) by means of the quenching effects on resonance Rayleigh scattering (RRS) and non-linear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS) intensities. In Britton–Robinson buffer medium (pH 6.02), I 3 − could react with DA to produce I −, which resulted in the decreases of the RRS, SOS and FDS intensities of the ethyl violet (EV)–I 3 − system, and the decreases of scattering intensity (Δ I) were directly proportional to the concentrations of DA in a certain range. The detection limit (3 σ) for DA was 0.0195 μmol/L for the RRS method, 0.286 μmol/L for the SOS method and 0.0985 μmol/L for the FDS method, respectively. In this work, the characteristics of absorption, RRS, SOS and FDS spectra of this reaction have been studied; the optimum reaction condition and influencing factors have been investigated. The methods were applied to the determination of DA in pharmaceutical samples with satisfactory results.

Bean sprout peroxidase biosensor based on l-cysteine self-assembled monolayer for the determination of dopamine

Abstract A new bean sprout peroxidase was immobilized on a gold electrode modified with self-assembled monolayers (SAM) of l -cysteine for the determination of dopamine in pharmaceutical samples using square wave voltammetry. In the bean sprout–(SAM)–Au electrode, the peroxidase, in the presence of hydrogen peroxide, catalyzes the oxidation of dopamine to the corresponding quinone, which is electrochemically reduced back to dopamine at +0.15 V vs. Ag/AgCl. The performance and the factors influencing the response of this biosensor were studied in detail. The best performance was obtained using 0.1 mol L −1 phosphate buffer solution (pH 6.0), 6.0 × 10 −5 mol L −1 hydrogen peroxide, frequency of 100 Hz, pulse amplitude of 80 mV and scan increment of 4.0 mV. The analytical curve was linear for dopamine concentrations from 9.91 × 10 −6 to 2.21 × 10 −4 mol L −1 and the detection limit was 4.78 × 10 −7 mol L −1 . The recovery of dopamine ranged from 98.0 to 111.8% and the relative standard deviation was 3.1% for a solution containing 1.30 × 10 −5 mol L −1 dopamine ( n = 6). The lifetime of this biosensor was 15 days (at least 300 determinations). The results obtained for dopamine determination in pharmaceutical formulations using the proposed bean sprout–SAM–Au electrode were in agreement with those obtained with the standard method at the 95% confidence level.

Development of a new biomimetic sensor based on an Fe IIIFe II complex for the determination of phenolic compounds

The dinuclear iron complex, [Fe IIIFe II(BPBPMP)(OAc) 2]ClO 4, containing the unsymmetrical ligand, 2-bis[{(2-pyridylmethyl)-aminomethyl}-6-{(2-hydroxybenzyl)(2-pyridylmethyl)}-aminomethyl]-4-methylphenol (H 2BPBPMP), has been described as being the first synthetic analogue for the redox properties of uteroferrin. This iron complex was employed in the construction of a new biomimetic sensor for the determination of phenolic compounds by square-wave voltammetry. The responses under optimized conditions were obtained for a 75:15:10% (w/w/w) composition of the graphite powder:Nujol:iron complex, 0.1 mol L −1 phosphate buffer solution (pH 7.0) and 4.5 × 10 −5 mol L −1 hydrogen peroxide. From the several phenolic compounds available (carbidopa, catechol, dopamine, hydroquinone, l-dopa and methyldopa), dopamine was selected, used for optimization of the biomimetic sensor and applied in determinations in pharmaceutical formulations. The analytical curve was linear for dopamine concentrations from 5.0 × 10 −5 to 6.5 × 10 −3 mol L −1 ( r = 0.9993). The recovery of dopamine from pharmaceutical sample ranged from 95.8 to 104.2% and the relative standard deviation was 2.6% for a solution containing 3.0 × 10 −3 mol L −1 dopamine ( n = 12). The lifetime of this biomimetic sensor was 6 months (at least 800 determinations). The results obtained for dopamine in pharmaceutical samples using the proposed biomimetic sensor and those obtained by the official method are in agreement at the 95% confidence level.

A zucchini-peroxidase biosensor applied to dopamine determination

A biosensor modified with peroxidase from crude extract of zucchini ( Cucurbita pepo) was developed for the determination of dopamine in pharmaceutical samples. This enzyme catalyses the oxidation of dopamine to dopaminequinone, in presence of hydrogen peroxide, which the electrochemical reduction can be followed at a peak potential of –0.02 V. The recovery of dopamine from the samples ranged from 94.8% to 106% and a rectilinear analytical curve for dopamine concentration from 5.0 × 10 –4 to 3.0 × 10 –3 mol L –1 ( r = 0.9982) was obtained. The detection limit was 2.6 × 10 –5 mol L –1 and the relative standard deviation was less than 1.2% for 7.9 × 10 –4 mol L –1 dopamine in 0.1 mol L –1 phosphate buffer solution at pH 6.0 ( n = 10).