Microelectrodes with gold nanoparticles and self-assembled monolayers for in vivo recording of striatal dopamine

Electrochemical determination of in vivo dopamine (DA) using implantable microelectrodes is essential for monitoring the DA depletion of an animal model of Parkinson's disease (PD), but faces substantial interference from ascorbic acid (AA) in the brain area due to similar electroactive characteristics. This study utilizes gold nanoparticles (Au-NPs) and self-assembled monolayers (SAMs) to modify platinum microelectrodes for improving sensitivity and specificity to DA and alleviating AA interference. With appropriate choice of ω-mercaptoalkane carboxylic acid chain length, our results show that a platinum microelectrode coated with Au-NPs and 3-mercaptopropionic acid (MPA) has approximately an 881-fold specificity to AA. During amperometric measurements, Au-NP/MPA reveals that the responsive current is linearly dependent on DA over the range of 0.01-5 μM with a correlation coefficient of 0.99 and the sensitivity is 2.7-fold that of a conventional Nafion-coated electrode. Other important features observed include fast response time (below 2 s), resistance to albumin adhesion and low detection limit (7 nM) at a signal to noise ratio of 3. Feasibility of in vivo DA recording with the modified microelectrodes is verified by real-time monitoring of electrically stimulated DA release in the striatum of anesthetized rats with various stimulation parameters and administration of a DA uptake inhibitor. The developed microelectrodes present an attractive alternative to the traditional options for continuous electrochemical in vivo DA monitoring.     

柠檬酸修饰(CA/GC)电极对多巴胺(DA)和肾上腺素(EP)同时检测

应用电沉积方法制备柠檬酸修饰电极(CA/GC), 差分脉冲法研究多巴胺(DA)和肾上腺素(EP)在该修饰电极上的电化学行为．结果表明, 两样品DA、EP在该电极的还原峰电位差380 mV, 而抗坏血酸(AA)在此电位区无还原峰, 因此可实现该修饰电极对DA和EP的同时检测, 而且高浓度AA不发生干扰．在pH 6.0的磷酸盐缓冲液中, DA和EP还原峰电流与其浓度分别在1.0×10-6 ~ 6.0×10-5 mol•L-1和2.0×10-6 ~ 6.0×10-5 mol•L-1 范围内呈线性关系．CA/GC电极制备简单, 重现性好, 可望用于多巴胺针剂(DA)和肾上腺素针剂(EP)的同时检测     

银掺杂聚L-酪氨酸修饰电极同时测定多巴胺、肾上腺素和抗坏血酸

用循环伏安法制备银掺杂聚L-酪氨酸修饰玻碳电极,研究了多巴胺、肾上腺素和抗坏血酸在其电极上的电化学行为,建立了同时测定多巴胺、肾上腺素和抗坏血酸的新方法。当3种组分共存时,在磷酸盐缓冲溶液(pH6.0)中,扫描速率为140mV/s,多巴胺和肾上腺素在修饰电极上分别产生还原峰,峰电位分别为0.198和-0.205V,多巴胺和肾上腺素氧化峰重叠,峰电位为0.313V(vs.Ag/AgCl);抗坏血酸产生一个氧化峰,峰电位0.108V(vs.Ag/AgCl)。多巴胺和肾上腺素的ΔEpc=0.403V,抗坏血酸的氧化峰与多巴胺和肾上腺素的ΔEpa=0.205V,用还原峰和氧化峰可同时测定多巴胺、肾上腺素和抗坏血酸,3种组分同时测定的线性范围分别为5.0×10-6～1.0×10-4mol/L,8.0×10-6～1.0×10-4mol/L和3.0×10-5～1.0×10-3mol/L;检出限分别为5.0×10-7,8.0×10-7和5.0×10-6mol/L。本方法用于人尿液中多巴胺、肾上腺素和抗坏血酸的同时测定,结果满意。     

Enhanced sensing of dopamine in the present of ascorbic acid based on graphene/poly(p-aminobenzoic acid) composite film

Graphene/p-aminobenzoic acid composite film modified glassy carbon electrode (Gr/p-ABA/GCE) was first employed for the sensitive determination of dopamine (DA). The electrochemical behavior of DA at the modified electrode was investigated by cyclic voltametry (CV), differential pulse voltametry (DPV) and amperometric curve. The oxidation peak currents of DA increased dramatically at Gr/p-ABA/GCE. The modified electrode was used to electrochemically detect dopamine (DA) in the presence of ascorbic acid (AA). The Gr/p-ABA composite film showed excellent electrocatalytic activity for the oxidation of DA in phosphate buffer solution (pH 6.5). The peak separation between DA and AA was large up to 220 mV. Using DPV technique, the calibration curve for DA determination was obtained in the range of 0.05-10 μM. The detection limit for DA was 20 nM. AA did not interfere with the determination of DA because of the very distinct attractive interaction between DA cations and the negatively Gr/p-ABA composite film. The proposed method exhibited good stability and reproducibility.     

Caffeic Acid‐Modified Glassy Carbon Electrode for the Simultaneous Determination of Epinephrine and Dopamine

A stable electroactive thin film of poly(caffeic acid) has been deposited on the surface of a glassy carbon electrode by potentiostatic technique in an aqueous solution containing caffeic acid. The electrochemical behaviors of epinephrine (EP), dopamine (DA) and their mixture have been studied. The oxidation peaks of EP and DA at the poly(caffeic acid) modified glassy carbon electrode appeared at the same potential, but the anodic peak currents of the mixture of DA and EP were almost equal to the sum of individual anodic peak currents of EP and DA, whereas the cathodic peak current only related to the concentration of DA under appropriate condition. Base on these, the simultaneous voltammetric measurement of EP and DA at the poly(caffeic acid) film modified electrode has been developed. Ascorbic acid (AA) had no interference with the simultaneous determination of EP and DA under the same condition because the oxidative peak potential of AA was less than those of DA and EP. The modified electrode has been satisfactorily used for the simultaneous determination of EP and DA in real samples.     

An electrochemical ascorbic acid sensor based on palladium nanoparticles supported on graphene oxide

In this study, an electrochemical ascorbic acid (AA) sensor was constructed based on a glassy carbon electrode modified with palladium nanoparticles supported on graphene oxide (PdNPs-GO). PdNPs with a mean diameter of 2.6 nm were homogeneously deposited on GO sheets by the redox reaction between PdCl₄²⁻ and GO. Cyclic voltammetry and amperometric methods were used to evaluate the electrocatalytic activity towards the oxidation of AA in neutral media. Compared to a bare GC or a Pd electrode, the anodic peak potential of AA (0.006 V) at PdNPs-GO modified electrode was shifted negatively, and the large anodic peak potential separation (0.172 V) of AA and dopamine (DA), which could contribute to the synergistic effect of GO and PdNPs, was investigated. A further amperometric experiment proved that the proposed sensor was capable of sensitive and selective sensing of AA even in the presence of DA and uric acid. The modified electrode exhibited a rapid response to AA within 5 s and the amperometric signal showed a good linear correlation to AA concentration in a broad range from 20 μM to 2.28 mM with a correlation coefficient of R = 0.9991. Moreover, the proposed sensor was applied to the determination of AA in vitamin C tablet samples. The satisfactory results obtained indicated that the proposed sensor was promising for the development of novel electrochemical sensing for AA determination.     

同时测定多巴胺和肾上腺素的大环镍膜修饰电极

研究了大环镍膜修饰电极对多巴胺和肾上腺素的电化学响应特性；结果表明，该修饰电极对多巴胺和肾上腺素的电极反应具有良好的催化活性，多巴胺和肾上腺素在修饰电极上的氧化电位比在裸铂电极上分别负移了230mV和70mV，使二者的阳极峰得到很好的分离，且灵敏度大为提高；将该修饰电极用于多巴胺和肾上腺素的同时检测，获得满意结果，生物体中的主要干扰物质抗坏血酸和NO2^-等均不干扰测定。     

Gold electrodes from compact discs modified with platinum for amperometric determination of ascorbic acid in pharmaceutical formulations

A simple, rapid and precise amperometric method has been developed for quantification of ascorbic acid (AA) in pharmaceutical formulations using flow-injection analysis (FIA). A slice of recordable compact disc (CD) modified by electrodeposition of platinum was employed as the working electrode. The proposed flow system allows determinations in the 1 mumol l(-1) of the analyte and enables 90 determinations per h, employing only 150-mul sample. The method permits the direct quantification of ascorbic acid in many pharmaceutical products, avoiding cumbersome processes as previous separations, solvent extraction or sample filtration. This new procedure was applied to commercial pharmaceutical tablets and the results obtained were identical than the ones obtained by the classical iodometric method. The calibration plots for freshly prepared ascorbic acid standards were highly linear in the concentration range of 1-10 mumol l(-1) with a relative standard deviation (R.S.D.) <1%. For all real samples studied, the deviations were situated between 0.5 and 8.7%.     

Modified platinum electrode with phytic acid and single-walled carbon nanotube: Application to the selective determination of dopamine in the presence of ascorbic and uric acids

A platinum (Pt) electrode modified by single-walled carbon nanotubes (SWNTs) and phytic acid (PA) was investigated by voltammetric methods in buffer solution. The PA-SWNTs/Pt-modified electrode demonstrated substantial enhancements in electrochemical sensitivity and selectivity towards dopamine (DA) in the presence of L-ascorbic acid (AA) and uric acid (UA). The PA-SWNTs films promoted the electron transfer reaction of DA, while the PA film, acting as a negatively charged linker, combined with the positively charged DA to induced DA accumulation in the film at pH under 7.4. However, the PA film restrained the electrochemical response of the negatively charged AA due to the electrostatic repulsion. The anodic peak potentials of DA, AA and UA could be separated by electrochemical techniques, and the interferences from AA and UA were effectively eliminated in the DA determination. Linear calibration plots were obtained in the DA concentration range of 0.2-10 μM and the detection limit of the DA oxidation current was determined to be 0.08 μM at a signal-to-noise ratio of 3. The results indicated that the modified electrode can be used to determine DA without interference from AA and UA, while ensuring good sensitivity, selectivity, and reproducibility.     

Electropolymerized film of functionalized thiadiazole on glassy carbon electrode for the simultaneous determination of ascorbic acid, dopamine and uric acid

The present study reports the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in 0.20 M phosphate buffer solution (pH 5.0) using electropolymerized ultrathin film of 5-amino-2-mercapto-1,3,4-thiadiazole (AMT) on glassy carbon (GC) electrode. The bare GC electrode does not separate the voltammetric signals of AA, DA and UA. However, electropolymerized AMT (p-AMT) modified GC electrode not only resolved the voltammetric signals of AA, DA and UA but also dramatically enhanced their oxidation peak currents when compared to bare GC electrode. The enhanced oxidation currents for AA, DA and UA at p-AMT modified electrode are due to the electrostatic interactions between them and the polymer film. Using amperometric method, we achieved the lowest detection of 75 nM AA, 40 nM DA and 60 nM UA at p-AMT modified electrode. The amperometric current was linearly increased from 200 nM to 0.80 mM for each AA, DA and UA and the lowest detection limit was found to be 0.92, 0.07 and 0.57 nM, respectively (S/N = 3). The practical application of the modified electrode was demonstrated by the determination of DA in dopamine hydrochloride injection.     

Pt Nanoparticle‐modified Carbon Fiber Microelectrode for Selective Electrochemical Sensing of Hydrogen Peroxide

We report a simple approach to the production of carbon fiber‐based amperometric microbiosensors for selective detection of hydrogen peroxide (H₂O₂), which was achieved by electrometallization of carbon fiber microelectrodes (CFMs) by electrodeposition of Pt nanoparticles. The Pt‐carbon hybrid sensing interface provided a sensitivity of 7711±587 μA ? mM^?1 ? cm^?2, a detection limit of 0.53±0.16 μM (S/N=3), a linear range of 0.8 μM–8.6 mM, and a response time of <2 sec. The morphologies of the Pt nanoparticle‐modified CFMs were characterized by scanning electron microscopy. To achieve selectivity, permseletive layers, polyphenylenediamine (PPD) and Nafion, were deposited resulting in exclusion of the anionic and cationic interferents, ascorbic acid and dopamine, respectively, at their physiologically relevant concentrations. The resultant sensors displayed a sensitivity to hydrogen peroxide of 1381±72 μA ? mM^?1 ? cm^?2, and a detection limit of 0.86±0.19 μM (S/N=3). This simple and rapid metallization method converts carbon fiber microelectrodes, which are readily accessible, to microscale Pt electrodes in 2 min, providing a platform for oxidase‐based amperometric biosensors with improved spatial resolution over more commonly used platinum electrode array microprobes.     

Fast batch injection analysis of H(2)O(2) using an array of Pt-modified gold microelectrodes obtained from split electronic chips

A fast and robust analytical method for amperometric determination of hydrogen peroxide (H(2)O(2)) based on batch injection analysis (BIA) on an array of gold microelectrodes modified with platinum is proposed. The gold microelectrode array (n=14) was obtained from electronic chips developed for surface mounted device technology (SMD), whose size offers advantages to adapt them in batch cells. The effect of the dispensing rate, volume injected, distance between the platinum microelectrodes and the pipette tip, as well as the volume of solution in the cell on the analytical response were evaluated. The method allows the H(2)O(2) amperometric determination in the concentration range from 0.8 μmolL(-1) to 100 μmolL(-1). The analytical frequency can attain 300 determinations per hour and the detection limit was estimated in 0.34 μmolL(-1) (3σ). The anodic current peaks obtained after a series of 23 successive injections of 50 μL of 25 μmolL(-1) H(2)O(2) showed an RSD<0.9%. To ensure the good selectivity to detect H(2)O(2), its determination was performed in a differential mode, with selective destruction of the H(2)O(2) with catalase in 10 mmolL(-1) phosphate buffer solution. Practical application of the analytical procedure involved H(2)O(2) determination in rainwater of S?o Paulo City. A comparison of the results obtained by the proposed amperometric method with another one which combines flow injection analysis (FIA) with spectrophotometric detection showed good agreement.     

Simultaneous determination of epinephrine, uric acid and xanthine in the presence of ascorbic acid using an ultrathin polymer film of 5-amino-1,3,4-thiadiazole-2-thiol modified electrode

This paper describes the simultaneous determination of epinephrine (EP), uric acid (UA) and xanthine (XN) in the presence of ascorbic acid (AA) using electropolymerized ultrathin film of 5-amino-1,3,4-thiadiazole-2-thiol (p-ATT) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 5). Although bare GC electrode resolves the voltammetric signals of AA and XN, it fails to resolve the voltammetric signals of EP and UA in a mixture. However, the p-ATT modified electrode not only separates the voltammetric signals of AA, EP, UA and XN with potential difference of 150, 120 and 400 mV between AA-EP, EP-UA and UA-XN, respectively but also shows higher oxidation current for these molecules. The p-ATT modified electrode exhibits excellent selectivity towards the oxidation of EP, UA and XN in the presence of 40-fold higher concentration of AA. Further, the p-ATT modified electrode was also used for the selective determination of EP in the presence of 40-fold higher concentrations of AA, UA and XN. Using amperometric method, we achieved the lowest detection of 40 nM EP and 60 nM each UA and XN. The amperometric current response was increased linearly with increasing EP concentration in the range of 4.0 × 10⁻⁸ to 4.0 × 10⁻⁵ M and the detection limit was found to be 27 × 10⁻¹¹ M (S/N = 3). The practical application of the present modified electrode was demonstrated by determining the concentration of EP in epinephrine tartrate injection and XN in human urine samples.     

Selective Detection of Dopamine and Its Metabolite,DOPAC, in the Presence of Ascorbic Acid Using Diamond Electrode Modified by the Polymer Film

The surface of boron‐doped diamond (BDD) electrode is modified by the polymer film for the first time. The cationic polymer film of N,N‐dimethylaniline (DMA) is electrochemically deposited on BDD electrode surface. This polymer (PDMA) film‐coated BDD electrode is used as a sensor which selectively detect dopamine (DA) in the presence of ascorbic acid (AA). This electrode also can detect both DA and its metabolite, 3,4‐dihydroxy phenyl acetic acid (DOPAC) in the presence of AA in the range of the physiological concentrations of these species. Favorable ionic interaction (i.e., electrostatic attraction) between the PDMA film and AA or DOPAC lowers their oxidation potentials and enhances the current response for AA and DOPAC compared to that at the bare electrode. The PDMA film also shows a hydrophobic interaction with DA and DOPAC. In cyclic voltammetric measurements, the PDMA film‐coated electrode can successfully separate the oxidation potentials for AA and DA coexisting in the same solution and the separation is about 200 mV. AA oxidizes at more negative potential than DA. In square‐wave voltammetry, the sensitivity of the PDMA film‐coated BDD electrode for DA in the presence of higher concentration of AA is higher than that of the PDMA film‐coated glassy carbon electrode. The hydrodynamic amperometric experiments confirm that the oxidation of AA is not affected by the oxidized product of DA and vice versa. So, unlike the bare electrode the catalytic oxidation of AA by the oxidized DA is eliminated at the PDMA film‐coated BDD electrode. The sensitivities of the modified electrode for AA, DA and DOPAC, which are present in the same solution with their physiological concentration ratios, are calculated to be 0.070, 0.363 and 0.084 μA μM^?1, respectively. The modified electrode exhibits a stable and sensitive response to DA.     

Simultaneous spectrophotometric determination of mercury and palladium with Thio-Michler's Ketone using partial least squares regression and orthogonal signal correction

A simple, novel and sensitive spectrophotometric method was described for simultaneous determination of mercury and palladium. The method is based on the complex formation of mercury and palladium with Thio-Michler's Ketone (TMK) at pH 3.5. All factors affecting on the sensitivity were optimized and the linear dynamic range for determination of mercury and palladium found. The simultaneous determination of mercury and palladium mixtures by using spectrophotometric method is a difficult problem, due to spectral interferences. By multivariate calibration methods such as partial least squares (PLS), it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Orthogonal signal correction (OSC) is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for PLS calibration of mixtures without loss of prediction capacity using spectrophotometric method. In this study, the calibration model is based on absorption spectra in the 360-660 nm range for 25 different mixtures of mercury and palladium. Calibration matrices were containing 0.025-1.60 and 0.05-0.50 microg mL(-1) of mercury and palladium, respectively. The RMSEP for mercury and palladium with OSC and without OSC were 0.013, 0.006 and 0.048, 0.030, respectively. This procedure allows the simultaneous determination of mercury and palladium in synthetic and real matrix samples good reliability of the determination.     

Enhanced Electrocatalytic Activity of Ni‐CNT Nanocomposites for Simultaneous Determination of Epinephrine and Dopamine

A promising electrochemical sensor based nickel‐carbon nanotube (Ni‐CNT) modified on glassy carbon (GC) electrode had been developed and the properties of the modified electrode were characterized by multispectroscopic analysis. The fabricated sensor (GC/Ni‐CNT) electrode was utilized to determine the catecholamines such as epinephrine and dopamine simultaneously. Differential pulse voltammetry and amperometry were used to verify the electrochemical behavior of the studied compounds. The GC/Ni‐CNT based amperometric sensor showed a wide linear range and low detection limit with high analytical sensitivity of 8.31 and 6.61 μA μM^?1 for EP and DA, respectively which demonstrates better characteristics compared to other electrodes reported in the literature. Further, no significant change in amperometric current response was observed in presence of biological interference species such as glucose, cysteine, citric acid, uric acid and ascorbic acid in the detection of EP and DA. The utility of this GC/Ni‐CNT electrode was well established for the determination of EP and DA in human urine samples.     

Preparation and characterization of PtAu hybrid film modified electrodes and their use in simultaneous determination of dopamine, ascorbic acid and uric acid

A novel biosensor was fabricated by electrochemical deposition of platinum and gold nanoparticles (nanoAu) with l-Cysteine on glassy carbon electrode. It was found that the nanoAu particle size distribution range was (50-80 nm), and the platinum particle size range was (200-300 nm). The hybrid film could be produced on gold and transparent indium tin oxide electrodes for different kind of studies such as electrochemical quartz crystal microbalance (EQCM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) and electrochemical studies. The PtAu hybrid film was applied to the electro catalytic oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA) at pH 4.0 using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified electrode was quite effective not only to detect DA, AA and UA individually but also in simultaneous determination of these species in a mixture. The overlapping anodic peaks of DA, AA and UA were resolved into three well-defined voltammetric peaks in CV and DPV. The catalytic peak currents obtained from CV and DPV increased linearly with concentration. The relative standard deviation (% R.S.D., n = 10) for AA, DA and UA were less than 2.0% and DA, AA and UA can be determined in the ranges of 0.103-1.65, 0.024-0.384 and 0.021-0.336 mM, respectively. In addition, the modified electrode also shows good sensitivity, and stability. Satisfactory results were achieved for the determination of DA, AA and UA in dopamine injection solution, vitamin C tablets and human urine samples.     

A novel poly(taurine) modified glassy carbon electrode for the simultaneous determination of epinephrine and dopamine

A novel taurine modified glassy carbon electrode was prepared by electropolymerization method. The electrochemical behaviors of epinephrine (EP) and dopamine (DA) at the modified electrode were studied by cyclic voltammetry. The modified electrode exhibited enhanced sensitivity and excellent electrochemical discrimination to DA and EP. The cathodic peaks of the two species were well-separated with a potential difference of about 390 mV, so the poly(taurine) modified electrode was used for simultaneous voltammetric measurement of EP and DA by differential pulse voltammetry. Under the optimum conditions, the cathodic peak currents were linear to concentrations of EP and DA in the range of 2.0 × 10⁻⁶ to 6.0 × 10⁻⁴ mol L⁻¹ and 1.0 × 10⁻⁶ to 8.0 × 10⁻⁴ mol L⁻¹, respectively. The detection limits for EP and DA were 3.0 × 10⁻⁷ and 1.0 × 10⁻⁷ mol L⁻¹, respectively. Because the oxidation of ascorbic acid (AA) is an irreversible reaction at modified electrode, the interference of AA for determining EP and DA was eliminated. The modified electrode has been satisfactorily used for the simultaneous determination of EP and DA in pharmaceutical injections.     

Electropolymerization of Thin Film Conducting Polymer and Its Application for Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid

In this paper electropolymerization of a thin film of para‐phenylenediamine (PPD) is studied at glassy carbon electrode (GCE) in sulfuric acid media by cyclic voltammetry. The results showed that this polymer was conducting and had a reproducible redox couple in the potential region from 0.0 to 0.4 V in phosphate buffer solution. This modified GCE (p‐PPD‐GCE) was applied for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) using differential pulse voltammetry (DPV). The p‐PPD‐GCE in 0.1 M phosphate buffer solution (pH 5.0) separated the DPV signals of AA, DA and UA with sufficient potential differences between AA–DA and DA–UA and also enhanced their oxidation peak currents. The oxidation currents were increased from 2.0 to 2000.0 µM for AA, 10.0 to 1250.0 µM for DA and 50.0 to 1600.0 µM for UA. The detection limits were evaluated as 0.4, 1.0 and 2.5 µM for AA, DA and UA, respectively (S/N=3).     

Selective Electrochemical Epinephrine Sensor Using Self‐Assembled Monomolecular Film of 1,8,15,22‐Tetraaminophthalocyanatonickel(II) on Gold Electrode

This article describes the highly sensitive and selective determination of epinephrine (EP) using self‐assembled monomolecular film (SAMF) of 1,8,15,22‐tetraamino‐phthalocyanatonickel(II) (4α‐Ni^IITAPc) on Au electrode. The 4α‐Ni^IITAPc SAMF modified electrode was prepared by spontaneous adsorption of 4α‐Ni^IITAPc from dimethylformamide solution. The modified electrode oxidizes EP at less over potential with enhanced current response in contrast to the bare Au electrode. The standard heterogeneous rate constant (k°) for the oxidation of EP at 4α‐Ni^IITAPc SAMF modified electrode was found to be 1.94×10^?2 cm s^?1 which was much higher than that at the bare Au electrode. Further, it was found that 4α‐Ni^IITAPc SAMF modified electrode separates the voltammetric signals of ascorbic acid (AA) and EP with a peak separation of 250 mV. Using amperometric method the lowest detection limit of 50 nM of EP was achieved at SAMF modified electrode. Simultaneous amperometric determination of AA and EP was also achieved at the SAMF modified electrode. Common physiological interferents such as uric acid, glucose, urea and NaCl do not interfere within the potential window of EP oxidation. The present 4α‐Ni^IITAPc SAMF modified electrode was also successfully applied to determine the concentration of EP in commercially available injection.