Britton-Robinson Buffer Solution Research Articles

Sensitive electrochemical determination of yohimbine in primary bark of natural aphrodisiacs using boron-doped diamond electrode

For the first time, a simple and sensitive analytical method for the direct determination of yohimbine is presented using differential pulse voltammetry with a boron-doped diamond electrode. Two irreversible oxidation peaks, a distinct one at +0.80 and a second poorly-defined one at +1.65 V, were observed when cyclic voltammetry was carried out in Britton–Robinson buffer solution at pH 7 (vs. Ag/AgCl). With optimized differential pulse voltammetric parameters (pulse amplitude 100 mV, pulse time 25 ms, step potential 5 mV and scan rate 10 mV s−1), the current response of yohimbine at +0.80 V was linearly proportional to the concentration in the range from 0.25 to 90.9 μmol L−1 with a low detection limit of 0.13 μmol L−1 (0.046 mg L−1) and a good repeatability (relative standard deviation of 2.5% at 18.4 μmol L−1 for n = 6). The practical applicability of the developed method was demonstrated by the assessment of the total content of yohimbine in extracts of the primary bark of natural aphrodisiacs such as Pausinystalia yohimbe and Rauvolfia serpentina with recoveries in the range of 92–97%. The proposed electrochemical procedure represents an inexpensive and effective analytical alternative for the quality control analysis of products containing yohimbine and other biologically and structurally related alkaloids used as natural dietary supplements.

Synthesis and electrochemical characterization of sol–gel-derived RuO2/carbon nanotube composites

Ruthenium oxide was coated on multiwalled carbon nanotubes (MWCNTs) to obtain nanocomposite electrode which has a good response to the pH. To synthesize this electrode, gold and cobalt were coated on a stainless steel 304 substrates, respectively, and then, vertically aligned carbon nanotubes were grown on the prepared substrates by chemical vapor deposition. Gold reduced activity of the stainless steel, while cobalt served as a catalyst for growth of the carbon nanotube. Ruthenium oxide was then coated on MWCNTs via sol–gel method. At last, different techniques were used to characterize the properties of synthesized electrode including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction, and cyclic voltammetry. SEM results showed that the length of the carbon nanotubes varied with reaction time, and in this research, it was maintained around 9 μm with a diameter about 100 nm. Electrochemical analysis revealed that optimum sol concentration and heat treatment temperature to meet the best pH sensing response were 0.1 M RuCl3 sol and 200 °C, respectively. Moreover, the obtained electrode represented a linear and near-Nernstian response (about −63 mV/pH) throughout the whole pH range (2–12) of Britton–Robinson buffer solutions.

Boron-doped diamond electrochemical sensor for sensitive determination of nicotine in tobacco products and anti-smoking pharmaceuticals

A sensitive, selective and reliable electrochemical method for the determination of nicotine using differential pulse voltammetry on a bare boron-doped diamond electrode has been developed. Nicotine yielded a single oxidation peak at a highly positive potential of + 1.45 V (vs. Ag/AgCl/3 M KCl) in Britton–Robinson buffer solution at pH 8. The influence of supporting electrolyte, pH and scan rate on the current response of NIC was investigated. At optimized experimental conditions, a linear relation between peak current and concentration of nicotine was found for the range from 0.5 to 200 μM (0.08–32.9 mg L− 1) with a detection limit of 0.3 μM (0.05 mg L− 1) and a good repeatability (relative standard deviation of 2.1% at 25 μM concentration level, n = 10) was achieved without any electrode surface modification. The practical usefulness of the developed procedure was successfully demonstrated with the determination of nicotine in tobacco products and anti-smoking pharmaceuticals with results similar to those obtained by a high-performance liquid chromatography and to the contents declared by the manufacturer, respectively. Prior to analysis, the sample pretreatment includes only sonication and/or simple liquid–liquid extraction. The proposed sensor represents an effective electrochemical tool and a promising alternative for quality control analysis of products in tobacco and pharmaceutical industry.

In vitro study of the interaction of cysteine with a thiazide diuretic (hydrochlorothiazide) at different ph by voltammetric and spectroscopic techniques

The interaction of cysteine (RSH) with a thiazide diuretic, hydrochlorothiazide (HCTZ) was characterized by UV-Vis absorption spectroscopy and square-wave voltammetry in Britton-Robinson (B-R) buffer solution (with pH 5, 7 and 9). On the square-wave voltamogram of cysteine, the reduction peak current of mercurous cysteine thiolate (Hg2(RS)2) decreased and its peak potential shifted to more positive values with the addition of HCTZ. This results showed that the RSH interacted with HCTZ. The stoichiometry of HCTZ-RSH molecular complex was determined by voltammetric data with the result of 1: 1. By using linear regression analysis of the voltammetric data at pH 5, 7 and 9, the apparent formation constants of HCTZ-RSH complex were calculated to be 9.54 × 103, 2.80 × 104 and 2.55 × 104 M−1, respectively. At the same time, this interaction was also supported by UV-Vis spectroscopic measurements. According to the voltammetric and spectroscopic results, it was suggested that the interaction mode between RSH and HCTZ molecules might be a combination of hydrophobic interactions and hydrogen bonds.

Electrocatalytic activity of salicylic acid on Au@Fe3O4 nanocomposites modified electrode and its detection in tomato leaves infected with Botrytis cinerea

Salicylic acid (SA) is one of essential phytohormones in the regulation of many physiological processes, especially for the defense of plants under various biotic stresses. Although SA could be electrochemically detected with various ways, their application was limited by unsatisfactory detection performance, or the requirement of acid/alkaline solutions. In this study, glassy carbon electrodes (GCEs) were coated with chitosan (CS) and then modified using the nanocomposite of Au@Fe3O4 for the detection of SA. It was found that the Au@Fe3O4-CS modified GCEs could be applied for the electrochemical determination of SA in the Britton–Robinson buffer solution at pH 7.0. After the optimization of the concentration of Au@Fe3O4 and the pH value of the buffer solution for detection, the concentration of SA could be measured with the linear range from 1.0μM to 1.2mM and the lowest detection limit at 0.10μM based on differential pulse voltammetry. The electrochemical response of SA at the Au@Fe3O4 modified GCEs was stable and reproducible. Moreover, the modified electrodes were applied for monitoring time-dependent variation of SA extracted from normal leaves of tomatoes and those infected by fungal pathogen. Our investigation revealed that the Au@Fe3O4 modified GCE could effectively determinate SA in mild conditions with a wide linear range, which can be potentially applied for the study of defense mechanisms of plants.

Square-wave voltammetric determination of pantoprazole using ex situ plated antimony-film electrode

The antimony film electrode (SbFE) was used for expedient measurement of pantoprazole, i.e. an important pharmaceutical substance. The SbFE was prepared ex situ on a supporting glassy carbon electrode and employed in direct square-wave voltammetric mode. After studying and optimizing several experimental parameters, the electrode exhibited an auspicious electroanalytical performance in Britton–Robinson buffer solution with the calculated LOD of 9.1×10−7molL−1 and an excellent reproducibility with the RSD of ±0.8%. Actual applicability of the SbFE in organic electroanalysis was demonstrated via measuring low concentration levels of pantoprazole in a real pharmaceutical dosage form.

Analytical application of polymethylene blue-multiwalled carbon nanotubes modified glassy carbon electrode on anticancer drug irinotecan and determination of its ionization constant value

The voltammetric behavior of anticancer drug irinotecan (IRT) was investigated at poly (methylene blue)/multi-walled carbon nanotube (PMB/MWCNT) modified glassy carbon electrode (GCE). The modified electrode surface was characterized by a scanning electron microscope (SEM). The PMB/MWCNT modified GCE exhibits a distinct shift of the oxidation potential of IRT on the cathodic direction and a considerable enhancement of the peak current compared with bare electrode. The calibration curve was linear between the concentration range 8.0×10−6 and 8.0×10−5M with the detection limit of 2.14×10−7M by differential pulse voltammetry in pH 10.0 Britton–Robinson buffer solution. Controlled potential coulometry was applied to find transferred electron numbers due to the oxidation of IRT. In this study, the pKa value of IRT was also determined by the dependence of the retention factor on the pH of the mobile phase. The effect of the mobile phase composition on the ionization constant was studied by measuring the pKa at different acetonitrile–water mixtures, ranging between 35 and 50% (v/v) using the reversed-phase liquid chromatography (RP-LC) method with UV detector. IRT was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the stressed samples were detected by the proposed method. Sensitive, rapid, and fully validated electrochemical and RP-LC methods for the determination of IRT in its dosage form were presented in details.

Electrochemical Oxidative Detection of Guanosine‐5′‐triphosphate Based on a New Ionic Liquid Modified Carbon Paste Electrode

AbstractAn ionic liquid (IL) 1‐(3‐chloro‐2‐hydroxy‐propyl)‐3‐methylimidazolium trifluoroacetate was used as the modifier for the preparation of the modified carbon paste electrode (CPE). The IL‐CPE showed excellent electrocatalytic activity towards the oxidation of guanosine‐5′‐triphosphate (5′‐GTP) in a pH 5.0 Britton‐Robinson buffer solution. Due to the presence of high conductive IL on the electrode surface, the electrooxidation of 5′‐GTP was greatly promoted with a single well‐defined irreversible oxidation peak appeared. The electrode reaction was an adsorption‐controlled process and the electrochemical parameters of 5′‐GTP on IL‐CPE were calculated with the electron transfer coefficient (α) as 0.44, the electron transfer number (n) as 1.99, the apparent heterogeneous electron transfer rate constant (ks) as 2.21 × 10−9 s−1 and the surface coverage (ΓT) as 1.53 × 10−10 mol cm−2. Under the selected conditions a linear calibration curve between the oxidation peak currents and 5′‐GTP concentration was obtained in the range from 2.0 to 1000.0 μmol L−1 with the detection limit as 0.049 μmol L−1 (3σ) by differential pulse voltammetry. The proposed method showed good selectivity to the 5‘‐GTP detection without the interferences of coexisting substances and the practical application was checked by measurements of the artificial samples.

Kinetics Investigation and Determination of Pipoxolan Hydrochloride and Its Degradant Using Liquid Chromatography

An LC method was developed for the quantitative determination of pipoxolan hydrochloride (PPH) and its degradant. Forced degradation studies were performed on bulk sample using acid (1 M hydrochloric acid), alkaline (0.2 M sodium hydroxide), oxidation (0.33% hydrogen peroxide), heat (70 degrees C), and photolytic degradation. The chromatographic method was fine-tuned using the samples generated from forced degradation studies. Good resolution between the peaks corresponding to the degradants and the analyte was achieved on a Discovery C18 LC column (25 cm x 4.6 mm id, 5 pm particle size). The mobile phase was methanol-10 mM sodium dihydrogen phosphate (60+40, v/v); pH was adjusted to 6.5 using 0.2 M sodium hydroxide. Quantitation was achieved with UV detection at 214 nm based on peak area. The proposed LC method was used to investigate the kinetics of acidic and alkaline degradation processes of PPH at different temperatures, and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. The pH-rate profiles of degradation of PPH in Britton-Robinson buffer solutions within the pH range 2-12 were studied. The developed method was validated with respect to linearity, accuracy, precision, and robustness. Forced degradation studies proved the stability-indicating power of the method.

Voltammetric behavior and determination of doxycycline in pharmaceuticals at molecularly imprinted and non-imprinted overoxidized polypyrrole electrodes

In this paper, electrochemical behavior of a member of tetracycline group compounds doxycyline (DC) was investigated in 20, 30, 40% (v/v) acetonitrile (ACN)–water binary mixture at the pH of 2.0–4.0 prepared Britton–Robinson (BR) buffers, by the differential pulse voltammetric method (DPV). Voltammetric determination of DC was carried out using molecularly imprinted (MIP) and non-imprinted polypyrrole (NIP) modified electrodes. Both types of electrode were prepared by the cyclic voltammetric method. The effect of the ACN–water ratio and pH, on the performance of the MIP electrode was investigated and optimized. The highest anodic signal of DC with MIP electrode was obtained in BR buffer solution was prepared in 30% (v/v) ACN–water at pH 2.0. The detection limit was determined as 4.35×10−5M (S/N=3). The method was also applied for electrochemical determination of DC in pharmaceutical samples. The recovery factors for Tetradox® and Monodox® were found 96.30%, 61.18% respectively with the relative standard deviations 0.46 and 0.54. The results of experiments using two commercial drugs showed that the MIP electrode can be used as a sensor to determine DC in pharmaceuticals.

Electrochemical Detection of Amaranth in Food Based on the Expanded Graphite Paste Electrode

Abstract A sensitive and simple electrochemical method was developed for successful determination of amaranth in food samples by square-wave adsorptive stripping voltammetry based on an expanded graphite paste electrode (EGPE). The EGPE has strong and sensitive voltammetric responses to amaranth, owing to the multiporous structure and large surface area of EG. The electroanalytical determination of this azo dye was found to be optimal in Britton-Robinson buffer solutions (pH 7.0) under the following experimental conditions: accumulation time, 400 s; accumulation potential, 0.4 V; pulse amplitude, 25 mV; and frequency, 10 Hz. Under the optimum experimental conditions, the oxidation peak current was proportional to the concentration of amaranth over two ranges from 0.01 to 0.1 and 0.1 to 4.0 μM. These linear ranges of the EGPE toward amaranth were wider than other electrodes reported before. The LOD was estimated to be 0.005 μM (S/N = 3:1). The developed method was applied to the determination of amaranth in retsina samples, and the results were confirmed by HPLC. Statistical analysis of these data showed that the results of the two methods compared favorably. This work provides a simple and easy approach to the determination of amaranth in foods with high sensitivity and excellent selectivity.

Renewable silver-amalgam film electrode for voltammetric monitoring of solar photodegradation of imidacloprid in the presence of Fe/TiO2 and TiO2 catalysts

A rapid and sensitive voltammetric method has been developed for the characterization and determination of the imidacloprid insecticide by means of square-wave voltammetry (SWV) with a silver-amalgam film electrode (Hg(Ag)FE) in the aqueous Britton–Robinson buffer solution as the supporting electrolyte. In the investigated pH range between 2.0 and 9.0 two reduction peaks of imidacloprid were observed, and they were both obtained in a fairly negative potential range, (approximately from −0.8 to −1.5V). Their shape strongly depended on the pH of the supporting electrolyte. The analytical measurements, based on the first peak, were performed at the pH of 7.0, and imidacloprid was determined in the concentration range of 0.91−47.48μgcm−3. The reproducibility of the analytical signal was characterized by a relative standard deviation smaller than 1.0%, and the calculated values of detection and quantitation limits were 0.27μgcm−3 and 0.91μgcm−3, respectively. The applicability of the elaborated SWV method was tested by monitoring imidacloprid concentration during its solar photolytic and photocatalytic degradation in the presence of two heterogeneous catalysts: TiO2 and TiO2 modified with 1.9% w/w Fe (1.9% Fe/TiO2). Under photolytic conditions, imidacloprid degraded very slowly, and the presence of TiO2 as a catalyst accelerated the process, while 1.9% Fe/TiO2 showed a remarkable efficiency in the removal of imidacloprid under natural insolation. In all investigated cases the results obtained using the Hg(Ag)FE-SWV method were in agreement with those obtained by means of the comparative HPLC–DAD method, which confirmed that the developed voltammetric method can be used to monitor the degradation of imidacloprid.

Voltammetric investigation on interaction of Hyaluronic Acid with crystal violet and its analytical application

In this paper, the interaction of hyaluronic acid (HA) with crystal violet (CV) was investigated carefully by linear sweep voltammetry on the dropping mercury working electrode (DME). In pH 5.0 Britton-Robinson (B-R) buffer solution, CV has a sensitive, well-defined second order derivative linear sweep voltammetric reductive wave at –0.85 V (vs. SCE). After adding a certain amount of HA into CV solution, the reductive peak current decreased without any shift of reductive peak potential. Based on the difference in the reductive peak current, a new voltammetric method for the detection of HA was established. The reaction conditions and the electrochemical determination were studied and optimized. Under the optimized conditions, the decrease of peak current showed a good linear relationship with the HA concentration in the range from 10.0 to 40.0 mg/L. The linear regression equation was got as ∆ip″(nA)= 84.07 C–527.86 (mg/L) (n=8, γ=0.997) and the detection limit was calculated as 2.65 mg/L (3σ). This new established method was further used to HA determination in the synthetic samples with satisfactory results and good recovery. The stoichiometry of CV-HA complex was calculated and the binding mechanism was also discussed by the electrochemical data.

ELECTROCHEMICAL DETERMINATION OF ACETAMINOPHEN AT THE SURFACE OF A GLASSY CARBON ELECTRODE MODIFIED WITH MULTI-WALLED CARBON NANOTUBE

A multi-walled carbon nanotubes (MWCNTs) film coated glassy carbon electrode (GCE) was fabricated, and the electrochemical behavior of acetaminophen (AAP) was studied in Britton–Robinson (BR) buffer (pH 7.0), using cyclic voltammetry (CV), square-wave voltammetry (SWV) and differential pulse voltammetry (DPV). Cyclic voltammograms of AAP showed enhanced redox responses for the MWCNT/GCE with respect to the bare GCE. The anodic peak potential shifted to less positive values by increasing the pH. The electrochemical oxidation of AAP at MWCNT/GCE was quasi-reversible and diffusion-controlled. Experimental parameters, such as pH, scan rate, SW frequency and step height, were optimized for AAP measurement. Under the optimum pH of 7.0 in 0.1 M BR buffer solution, the DPV anodic peak current showed a linear relation versus AAP concentration in the range of 7.9×10-7 to 3.4×10-4 M with a detection limit of 3.3×10-7 for DPV, and from 6.5×10-7 to 3.5×10-4 M for SWV with a detection limit of 2.1×10-7 (signal to noise = 3). Moreover, this method demonstrated good reproducibility (RSD = 1.3%, n = 10) and long-term stability. These have been applied to the determination of AAP in effervescent dosage samples.

Electrochemistry of adenosine-5′-diphosphate on ionic liquid modified carbon electrode and its detection

A sensitive electrochemical method was proposed for the determination of adenosine-5′-diphosphate (ADP) on an ionic liquid (IL) 1-(3-chloro-2-hydroxy-propyl)-3-methylimidazole chloride modified carbon paste electrode (CPE) in a pH 4.5 Britton-Robinson (B-R) buffer solution. Compared with CPE, IL modified CPE (CILE) showed strong electrocatalytic ability to promote the electrochemical oxidation of ADP. A well-defined irreversible oxidation peak of ADP appeared at +1.381 V with an adsorption-controlled process, which was due to the presence of high conductive IL on the electrode. The experimental conditions were optimized and the electrochemical parameters of ADP were calculated with the electron transfer coefficient (α) as 0.293, the electron transfer number (n) as 1.23, the apparent heterogeneous electron transfer rate constant (k s) as 3.325 × 10−6 s−1 and the surface coverage (ΓT) as 0.92 × 10−8 mol/cm2. Under the optimum conditions, the oxidation peak current was linear to ADP concentration in the range from 3.0 to 1000.0 μmol/L with the detection limit as 2.78 μmol/L (3σ) by differential pulse voltammetry. The CILE also eliminated the interferences of commonly coexisting substances and was successfully applied to detect the ADP artificial samples.

Green electrochemical sensor for environmental monitoring of pesticides: Determination of atrazine in river waters using a boron-doped diamond electrode

A novel, simple and sensitive electrochemical method for the determination of atrazine using a square-wave voltammetry on boron-doped diamond electrode was developed. Atrazine provided a single well-defined reduction peak at −1.1V vs. Ag/AgCl electrode in Britton–Robinson buffer solution at pH 3. The effect of supporting electrolyte, pH and scan rate on the current response of atrazine was studied to select the optimum experimental conditions. The linear concentration range from 0.05 to 40μM (R2=0.999, n=6), the good repeatability (relative standard deviation of 2.9% at 10μM for n=6) and the detection limit of 10nM were achieved at optimized square-wave voltammetric parameters (step potential of 5mV, frequency of 60Hz and amplitude of 80mV). The influence of possible interfering agents appeared to be minor which evidently proved the good selectivity of method. The proposed method was successfully applied for the determination of atrazine in spiked river water samples with satisfactory recoveries (92 to 100%) and the good agreement to results obtained by reference high performance liquid chromatography method at confidence interval for 95% probability. In this way, boron-doped diamond could represent an environmentally acceptable (green) alternative to highly toxic mercury electrodes for monitoring of pesticides.

Determination of Perfluorooctane Sulfonate by Light Scattering-Fluorescence Ratio Method

Perfluorooctane sulfonate(PFOS) can quench the fluorescence of rhodamine B(RhB) in pH=1.81 Britton-Robinson(BR) buffer solution,and results in light scattering enhancement by electrostatic forces and hydrophobic interactions.In this work,a light scattering-fluorescence ratio method of PFOS was established with a common spectrofluorometer by measuring the light emission signals through one scanning,out of which a ratio of the intensity of light scattering at 340 nm to that of fluorescence at 596 nm could be obtained.The linear range is from 0.17 to 10.0 μmol/L,and the limit of detection(3σ) is 17 nmol/L.The method has been applied to the determination of PFOS in the environmental samples with RSD≤4.2%.

Determination of Trace Amounts of Sulfamethizole Using a Multi-Walled Carbon Nanotube Modified Electrode: Application of Experimental Design in Voltammetric Studies

The present paper is the first report for the simultaneous investigation of various factors affecting the oxidation peak currents of sulfamethizole (SM) in a 0.20 M Britton-Robinson (B-R) buffer solution. Experimental factors (pH, multiwalled carbon nanotube amount, scan rate, step potential, and modulation amplitude) on voltammetric determination of SM were optimized simultaneously by a central composite rotatable design (CCRD). Then, in the optimized conditions, differential pulse voltammetry (DPV) was applied for selective determination of SM at the surface of a multi-walled carbon nanotube modified carbon paste electrode (MWCNT/CPE).The modified electrode showed enhanced effect on the oxidation peak current of SM. In these conditions the linear dynamic range for SM was from 0.10 up to 131.94 µM and the detection limit was found to be 14.31 nM. The characterization of MWCNT/CPE was carried out bycyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Also, linear sweep voltammetry (LSV) and chronocoulometry of SM were studied. Using these techniques, the diffusion coefficient (D = 4.91 × 10−5 cm2 s−1) and the kinetic parameters such as the electron transfer coefficient (α = 0.79) and exchange current density (j0 = 2.78 × 10−12 µA cm−2) for SM were calculated. The proposed method was then successfully applied to the determination of SM in plasma samples.

Determination of Propylthiouracil in Pharmaceuticals by Differential Pulse Voltammetry Using a Cathodically Pretreated Boron-Doped Diamond Electrode

A simple procedure is described for the determination of propylthiouracil (PTU) by differential pulse voltammetry (DPV) using a cathodically pretreated boron-doped diamond (BDD) electrode. Cyclic voltammetry studies indicate that the oxidation of PTU is irreversible at a peak potential of 1.42 V (vs. Ag/AgCl (3.0 mol L-1 KCl)) in a Britton-Robinson (BR) buffer solution (pH 2.0). Under optimized conditions, the obtained analytical curve was linear (r = 0.9985) for the PTU concentration range of 1.0 to 29.1 mmol L-1 in a BR buffer solution (pH 2.0), with a detection limit of 0.90 mmol L-1. The proposed method was successfully applied in the determination of PTU in pharmaceutical samples, with results in agreement at a 95% confidence level with those obtained using an official titration method.

A highly sensitive sensor for synephrine detection based on multi-walled carbon nanotubes modified glass carbon electrodes

A sensitive, fast and cheap sensor, based on a glassy carbon electrode (GCE) modified with a multiwalled carbon nanotubes (MWCNTs)/Nafion film, is reported for the quantitative determination of synephrine in the Chinese traditional herbal drug Pericarpium citri reticulatae using . The electrochemical behavior of synephrine at this sensor was explored in Britton–Robinson buffer solution using cyclic voltammetry. An oxidation peak at 1027 mV was observed for synephrine when a bare GCE was used, whereas an oxidation peak at 998 mV with greatly enhanced peak current was obtained at the MWCNTs/Nafion/GCE, showing the electrocatalytic nature of the modified electrode. Moreover, cyclic voltammetric studies indicated that the oxidation of synephrine at the modified electrode was irreversible, adsorption controlled and involved two electrons. A calibration plot of oxidation peak current versus synephrine concentration was linear in the range of 1 × 10−8 to 1 × 10−5 mol L−1. The detection limit of synephrine was found to be 8 × 10−9 mol L−1 by linear sweep voltammetry . The effect of pH and scan rate of synephrine were studied. This is currently the first report on the determination of trace synephrine by a purely electroanalytical method. The analytical performance of this sensor was also evaluated for the detection of synephrine in real samples.