Differential Pulse Stripping Voltammetry Research Articles

Nanostructured carbon black for simultaneous electrochemical determination of trace lead and cadmium by differential pulse stripping voltammetry.

Nanostructured carbon black (CB) was first employed directly in this paper for the simultaneous electrochemical determination of trace Pb(II) and Cd(II) using differential pulse anodic stripping voltammetry. The morphology and surface properties of conductive CB were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy and Raman spectroscopy. Special pore structures, as well as surface chemical functional groups, endow CB with excellent catalytic and adsorption properties. Some parameters affecting electrical analysis performance were investigated systematically including deposition time and potential, pH value of solution, volume of suspension, amount of Bi(III) and Nafion solution. CB–Nafion–glassy carbon electrode sensor linear response ranges from 6 to 1000 nM for selective and simultaneous determination. The detection limits were calculated to be 8 nM (0.9 µg l−1) for Cd(II) and 5 nM (1.0 µg l−1) for Pb(II) (S/N = 3) for the electrocatalytic determination under optimized conditions. The method was successfully used to the determination of actual samples and good recovery was achieved from different spiked samples. Low detection limits and good stability of the modified electrode demonstrated a promising perspective for the detection of trace metal ions in practical application.

3D SWCNTs-coumarin hybrid material for ultra-sensitive determination of quercetin antioxidant capacity

The novel 7-propinyloxy-3-(p-propinyloxyphenyl) coumarin having terminal ethynyl groups was synthesized for the first time. This coumarin has been successfully bounded covalently to single walled carbon nanotubes (SWCNTs) via the azide-alkyne Huisgen cycloaddition (Click) reaction for the preparation of a 3D hybrid material. Glassy carbon electrode was modified with the 3D SWCNTs-coumarin hybrid material for the determination of quercetin antioxidant. The proposed modified electrode is nearly 10-fold more sensitive than the bare electrode by applying the differential pulse stripping voltammetry (DPSV). In addition, the parameters of DPSV measurements such as accumulation time, accumulation potential and pH were optimized as 20 s, 200 mV and pH 2 Britton-Robinson buffer solutions in 1 μM quercetin, respectively. In the optimized conditions, the linear working range from 0.25 to 3 μM was determined. The detection and quantification limits of quercetin were found to be 20 nM and 66 nM by DPSV on the modified electrode, respectively. The DPSV procedure was also applied to test different brand tea real samples and quercetin was determined by a standard addition method with the recovery between 97.00 and 103.10.

Application of stripping voltammetry method for the analysis of available copper, zinc and manganese contents in soil samples

ABSTRACTDetermination of copper (Cu), zinc (Zn) and manganese (Mn) micronutrients in soil samples have been studied for an efficient fertiliser application. Plant-available micronutrients of soils were extracted with DTPA extraction procedure, then differential pulse stripping voltammetry (DPSV) and square wave stripping voltammetry (SWSV) methods were performed with inexpensive and disposable pencil graphite electrode for determination of Cu(II), Zn(II) and Mn(II). Parameters such as deposition potential, deposition time, pH and concentration of the supporting electrolyte were optimised for these ions. Under optimised conditions, the limits of detection were found as 0.01 mg L−1 for Cu(II) and 0.02 mg L−1 for Zn(II) and 0.25 mg L−1 for Mn(II). Relative standard deviation (%RSD) was 6.80, 8.86 and 3.29 for Cu(II), Zn(II) and Mn(II), respectively. The experimental study was conducted using a flame atomic absorption spectroscopy. The described stripping voltammetry methods were successfully applied for the determination of Mn(II), Cu(II) and Zn(II) in soil samples.

Low symmetric metallophthalocyanine modified electrode via click chemistry for simultaneous detection of heavy metals

Beside different methods and materials used to develop electrochemical sensors, the modification of the electrode using click reaction based on metallophthalocyanine (MPc) compounds are shown to improve the stability and sensitivity of the sensor. This work reported the development of electrochemical sensor for mercury (II), Lead (II), copper (II) and cadmium (II) ions detection based on the synthesized novel low symmetry alkyne terminated cobalt Phthalocyanine (CoPc) derivative. Differential pulse stripping voltammetry (DPSV) technique was employed for the first time in simultaneous determination of trace levels of the above metal ions using modified glassy carbon electrode (GCE) via click chemistry. Under the optimum experimental conditions, the anodic peak current is proportional to the concentrations of metal ions over a wide range of 0 to 0.1 mM with nanolevel detection limit of 81.94, 327.71, 55.87 and 347.06 nM and the sensitivity of 866.23 ± 5.48, 215.82 ± 2.16, 1979.48 ± 11.47 and 204.50 ± 1.10 μA/mM for Hg(II), Cu(II), Pb(II) and Cd(II), respectively. The selectivity of the clicked-CoPc modified GCE toward Hg(II), Cu(II), Pb(II), Cd(II) present no interference from these metals ions. The fabricated electrochemical sensor exhibited very good electrochemical properties such as good reproducibility, stability, reusability and is suitable for the detection of heavy metal ions in tap water in our laboratory.

Determination of cadmium(II) using a glassy carbon electrode modified with a Cd-ion imprinted polymer

This study reports design and synthesis of a cadmium(II)-selective electrode using cadmium (II) imprinted polymer nanoparticles (IIP-NPs) and uses the electrode for differential pulse voltammetry determination of cadmium ions. The IIP-NPs were prepared by co-precipitation polymerization of 4-vinylpyridine, ethylene glycol dimethacrylate, 2,2′-azobisisobutyronitrile, 2-aminobenzimidazole and cadmium ions, in acetonitrile solution. After polymerization, the Cd(II) ions were leached out of the polymer nanoparticles with dilute hydrochloric acid to provide some cavities for hosting Cd(II). Also, a glassy carbon electrode was modified with NIP-NPs and differential pulse stripping voltammetry was employed as a detection tool after open-circuit sorption of Cd(II) ions into the electrode and its reduction to Cd(0). A clear difference in response was observed between electrodes modified with IIP-NPs and those without IIP-NPs. The modified electrode responded to Cd(II) with a linear concentration ranges from 0.008 to 0.05 μM and in the ranges from 0.05 to 0.80 μM. The detection limit of the sensor for Cd(II) was 1 × 10−4 μM (at S/N = 3), while it was successfully applied to trace determination of Cd(II) in samples of spiked environmental water.

Novel Low Symmetric Alkyne Terminated Metallophthalocyanine Modified Electrode Via Click Chemistry for Electrochemical Determination of Mercury (II)

An electrochemical method for the determination of trace levels of mercury(II) ions using metallophthalocyanine (MPc) modified glassy carbon electrode (GCE) via click chemistry by differential pulse stripping voltammetry (DPSV) is described for the first time. In this report, the novel synthesized low symmetry alkyne terminated cobolt Phthalocyanine (CoPc) derivative was prepared and characterized using FTIR, MS, UV-Vis, Elemental Analysis and cyclic voltammetry. Operational parameters such as number of scan for grafting step, concentration of CoPc derivative for clicking solution, and scanning potential range were optimized. Under the optimum experimental conditions, the anodic peak current is proportional to the concentrations of mercury over a wide range of 0.1 to 0.8 mM with the lowest detectable concentration of 440 nM. The selectivity of the CoPc modified GCE via click chemistry towards mercury in the presence of potential interferents such as copper, lead, cadmium and zinc was well studied. The fabricated electrochemical sensor exhibited very good electrocatalytic properties such as good reproducibility, stability and is suitable for the detection of mercury in tap water and seawater. Figure 1

Electrocatalitic behaviour of serpentinite modified carbon paste electrode

Electrochemistry of carbon paste electrode which contained serpentinite powder and graphite in 1:1 weight ratio was examined in three-electrode cell regarding its electrocatalytic and sensing properties. For this purpose, red-ox reactions of potassium ferrocyanide in aqueous solutions as benchmark media and pesticide tebufenozide (TBF) were examined. Serpentinite characterization performed by XRPD, SEM/EDX, and FTIR confirmed the structure typical for this mineral rock. Voltammetric analyses have in all cases shown that serpentinite modified carbon paste electrode (S-CPE) possess superior electrocatalytic activity in contrast to bare CPE for the red-ox reactions of K4[Fe(CN)6]. The enlargement of the peak currents, higher electroactive surface area, and the decline of the peak-to-peak separation are a proof of reversible and faster electron transfer kinetics for S-CPE. The effect of pH on the electrochemical behaviour of TBF was investigated in Britton-Robinson buffer solutions in range from 2.0 to 7.0 and showed the best analytical performance at pH5.0. The oxidation peak of TBF appeared at +0.5V vs. Ag/AgCl under conditions optimized for the determination of TBF in the differential pulse stripping voltammetry: initial potential +0.1V, end potential +0.9V, accumulation potential −0.35V, accumulation time 120s, and the scan rate 50mVs−1.

Sensitive Electrochemical Capsaicin Sensor Based on a Screen Printed Electrode Modified with Poly(sodium 4-styrenesulfonate) Functionalized Graphite.

A sensitive capsaicin sensor was constructed based on a poly(sodium 4-styrenesulfonate) functionalized graphite modified screen printed electrode (PSS-Grp/SPE) in this study. The PSS-Grp and poly(diallyldimethylammonium chloride) functionalized graphite (PDDA-Grp) were easily synthesized by interacting Grp with PSS and PDDA through sonication, and resulted in negative and with positive charges on the surface, respectively. The prepared PSS-Grp and PDDA-Grp were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ultraviolet and visible spectroscopy (UV-vis). The electrochemical performance of PSS-Grp in a 50 μM capsaicin solution presented a current density of 33 μA cm-2, which was much higher than the PDDA-Grp of 1.5 μA cm-2. Our study showed that capsaicin could interact better with strong negative charges on the PSS-Grp/SPE surface to give a higher electrochemical response. The direct electrochemical sensing of capsaicin was achieved at PSS-Grp/SPE using differential pulse stripping voltammetry (DPSV) under the optimized conditions.

Voltammetric Understanding of Ionizable Doxorubicin Transfer Reactions across Liquid/liquid Interfaces and Sensor Development

The transfer characteristics of the ionizable anticancer drug doxorubicin (DOX) across a polarized interface between two immiscible electrolyte solutions (ITIES) were investigated using voltammetry. Aqueous buffer solutions at different pH with a controlled ionic strength were interfaced with 1,2-dichloroethane in order to understand the nature of charged DOX. Following voltammetric investigation, an ionic partition diagram was established which can be correlated to the lipophilicity of DOX and further used for predicting specific charged forms of DOX in the aqueous phase at a certain pH value. Thermodynamic properties including the formal transfer potential, partition coefficient and Gibbs energy of DOX transfer processes at the water/1,2-DCE interface were also evaluated. At a buffer solution of pH 7 the peak current responsible for protonated DOX (HDOX+) transfer across the ITIES gave a good linear relationship with the DOX concentration enabling a DOX sensitive voltammetric sensor to be developed. As a sensing demonstration for practical applications, a microhole supported water/organic gel interface was fabricated and used in conjunction with differential pulse stripping voltammetry (DPSV) to quantitatively analyze HDOX+ in buffer followed by applying to local river water and human serum sample solutions. The results from the HDOX+ sensor were then compared to those obtained using conventional high-performance liquid chromatography (HPLC).

Electrodeposition of gold nanoparticles and reduced graphene oxide on an electrode for fast and sensitive determination of methylmercury in fish

Fish consumption is the main source of methylmercury (CH3Hg+) exposure for humans. In this study, gold nanoparticles and reduced graphene oxide (AuNPs-RGO) modified electrode was fabricated for determination of CH3Hg+ in fish. The AuNPs-RGO composite was synthesized by electroreduction method. The composite was characterized by scanning electron microscopy and energy dispersive spectra, X-ray diffraction and Raman spectroscopy. Electrochemical performance of the proposed sensor was studied by cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse stripping voltammetry. The excellent conductivity and large surface of graphene contributed to an improvement in the voltammetric stripping signal. Under the optimized conditions, the methylmercury concentration in the range from 3 to 24μgL−1 had a good linear relation with the peak current. The detection limit of AuNPs-RGO modified electrode was 0.12μgL−1. Finally, the developed electrode was applied to detect methylmercury in fish samples, and the obtained results were in good agreement with certified values.

Portable Sensor for the Detection of Choline and Its Derivatives Based on Silica Isoporous Membrane and Gellified Nanointerfaces.

A portable amperometric ion sensor was fabricated by integrating silica isoporous membrane (SIM) and organogel composed of polyvinyl chloride and 1,2-dichloroethane (PVC-DCE) on a 3D-printed polymer chip. The detection of ionic species in aqueous samples could be accomplished by adding a microliter of sample droplet to the sensor and by identifying the ion-transfer potential and current magnitude at the water/organogel interface array templated by SIM. Thanks to the ultrasmall channel size (2-3 nm in diameter), high channel density (4 × 108 μm-2), and ultrathin thickness (80 nm) of SIM, the ensemble of nanoscopic water/organogel (nano-W/Gel) interface array behaved like a microinterface with two back-to-back hemispherical mass diffusion zones. So, the heterogeneous ion-transfer across the nano-W/Gel interface array generated a steady-state sigmoidal current wave. The detection of choline (Ch) and its derivatives, including acetylcholine (ACh), benzoylcholine (BCh), and atropine (AP), in aqueous samples was examined with this portable sensor. Using differential pulse stripping voltammetry (DPSV), the quantification of these analytes was achieved with a limit of detection (LOD) down to 1 μM. Moreover, the portable ion sensor was insensitive to various potential interferents that might coexist in vivo, owing to size-/charge-based selectivity and antifouling capacity of SIM. With this priority, the portable ion sensor was able to quantitatively determine Ch and its derivatives in diluted urine and blood samples. The LODs for Ch, ACh, AP, and BCh in urine were 1.12, 1.30, 1.08, and 0.99 μM, and those for blood samples were 3.61, 3.38, 2.32, and 1.81 μM, respectively.

Use of carbon paste electrodes for the voltammetric detection of silver leached from the oxidative dissolution of silver nanoparticles

The widespread use of silver nanoparticles (Ag NPs) in consumer goods has raised concerns about the release of silver in environmental waters. Of particular concern is the oxidative dissolution of Ag NPs to release Ag+ ions, which are highly toxic to many aquatic organisms. Here, we have investigated the application of differential pulse stripping voltammetry (DPSV) with carbon paste electrodes (CPEs) in monitoring the oxidation of Ag NPs. Using a commercially available, unmodified carbon paste and 60-s deposition times, a detection limit of 3 nM Ag+ could be achieved. We demonstrate its selectivity for free Ag+ ions over Ag nanoparticles, allowing for analysis of the oxidation of Ag NPs without the need for separation of ions and nanoparticles prior to analysis. We applied this approach to investigate the effect of pH in the oxidative dissolution of Ag NPs, demonstrating the usefulness of CPEs in studies of this type.

Surfactant modified glassy carbon electrode as an efficient sensing platform for the detection of Cd (ӏӏ) and Hg (ӏӏ)

A highly sensitive electrochemical sensor using a novel surfactant 1-cyclohexyl-3-dodecanoylthiourea (CDT) as a recognition layer was developed for the detection of Cd2+ and Hg2+ using electrochemical impedance spectroscopy, chronocoulometry and a number of voltammetric techniques such as cyclic, square wave and differential pulse stripping voltammetry. For optimization, the effect of several experimental factors such as concentration of the surfactant, scan rate, pH, accumulation time, number of cycles and supporting electrolytes were investigated. The limits of detection quite lower than the danger level suggested by world health organization (WHO), Environmental protection agency (EPA) and European water quality (EWQ) suggested the suitability of our designed sensor for monitoring metal based water toxins. Theoretical studies carried out for the calculation of interaction energy of CDT with Hg2+ and Cd2+ supported the experimental findings. The validity of the proposed method for real water sample analysis was ensured from reasonable percentage recoveries and less than 4% RSD values. Moreover, the designed sensor demonstrated excellent discrimination ability for the target analytes in the presence of interfering agents.

The Polypyrrole/Multiwalled Carbon Nanotube Modified Au Microelectrode for Sensitive Electrochemical Detection of Trace Levels of Pb2+

The sensitive detection of trace levels of heavy metal ions such as Pb2+ is of significant importance due to the health hazard they pose. In this paper, we present a polypyrrole (PPy)/multiwalled carbon nanotube (MWCNT)-modified Au microelectrode. The PPy/MWCNT composite film was electrochemically deposited on the microelectrode by cyclic voltammetry (CV). The composite film was investigated by scanning electron microscope (SEM), CV, and electrochemical impedance spectroscopy (EIS), and the results show that this film presents a uniformly distributed and web-like entangled structure and good conductivity. Differential pulse stripping voltammetry (DPSV) was applied to determine trace levels of Pb2+. Experimental conditions including accumulation time and deposition potential were optimized. In optimal conditions, the PPy/MWCNT-modified microelectrode performed sensitive detection of Pb2+ within a concentration range from 1 to 100 μg·L−1, and the limit of detection was 0.65 μg·L−1 at the signal-to-noise ratio of three.

Fabrication of electrochemical nanosensor based on polyaniline film-coated AgNP-MWCNT-modified GCE and its application for trace analysis of fenitrothion

A simple, inexpensive, highly sensitive and selective electrochemical nanosensor based on electrochemically synthesized silver nanoparticles (AgNPs) and multiwalled carbon nanotubes (MWCNTs) was fabricated. The electrochemical pretreatment of modified electrode with conducting polyaniline film was performed to enhance the electrocatalytic activity, sensitivity, and detection limits. The designed electrochemical nanosensor was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FESEM), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The as-fabricated electrochemical sensor was applied for examining the electrochemical behavior of an organophosphorus (OP) pesticide, fenitrothion (FT) in surfactant media by adsorptive differential pulse stripping voltammetry (AdDPSV) and cyclic voltammetry (CV). Different experimental parameter such as pH, scan rate, accumulation time, and potential has been optimized for trace determination of FT. Various kinetics parameters like the number of electrons transferred (n), electron transfer coefficient (α), formal redox potential (E0), standard heterogeneous rate constant (k0), charge due to adsorption (Qads), surface coverage of FT (Γ), charge transfer coefficient (Rct), and apparent electron-transfer rate constant (kapp) were evaluated. FT exhibited a linear range from 0.1 to 5.67 μg mL−1 and 0.1 to 1.5 μg mL−1 with low detection limits of 0.000193 and 0.000265 μg mL−1 at the modified glassy carbon electrode (GCE) by AdDPSV and CV, respectively. The fabricated sensor exhibited good accuracy and stability and efficacy for quantitative determination of FT in some real samples with notable recoveries ranging from 95.2 to 100.04%.

Determinations of trace lead in various natural samples by a novel active microband-electrode probe

A novel active microband-electrode probe is introduced for determinations of trace lead in various natural samples. It integrates a micro electrode array (MEA) on a silicon substrate and a compact homemade potentiostat. On-chip microband gold electrodes, microband platinum electrodes and silver electrode compose a tri-electrode system. Homemade potentiostat performs cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV) measurements, not requiring external commercial potentiostat analyzer. Performances of the as-fabricated sensor are validated in CVs and DPSVs. The sensor shows lower noise than traditional setups. Linearity is outstandingly established from 0.2μgL−1 to 150μgL−1, and detection limit reaches as low as 0.06μgL−1. Other analytical properties as accuracy, precision and selectivity are also well obtained. This sensor is extensively adopted to detect trace lead in natural water, soil and fish. Results meet certified method (graphite-furnace atomic absorption spectrometer, GF-AAS) well, and validate promising applicability of the proposed method in many environmental areas.

Ultra-high sensitive voltammetric sensor modified by largely oxygenous functionalized ultrathin carbon nitride nanosheets for detection of Cu (II)

Enhancing the sensitivity of sensors is one of the most critical targets for the progress of analytical chemistry. Here in, an ultrasensitive voltammetric sensor for determination of Cu (II) was firstly prepared based on carbon nitride materials. Ultrathin carbon nitride nanosheets with large amount of oxygenous groups (ωO=19.9%, SBET=360.2m2g−1) was synthesized for the electrode modification via an improved Hummer’s method for the first time. The accumulation mechanism of the large amount of oxygenous groups on ultrathin carbon nitride nanosheets towards Cu (II) was also firstly verified employing cyclic voltammetry and X-ray photoelectron spectroscopy. The as-prepared electrode showed extremely high sensitivity and wide linear ranges in Cu (II) determination employing differential pulse stripping voltammetry with acceptable anti-contamination ability, repeatability, fabrication reproducibility, storage stability and anti-interference ability, whose limit of detection (S/N=3) is 2.3×10−15molL−1 with two linear relationships in 2.3×10−14–5.5×10−9 and 5.5×10−9–3.2×10−6molL−1. The determination of Cu (II) in environmental water samples showed satisfactory precision and accuracy employing the as-presented method. The simultaneous determination for Hg (II), Pb (II) and Cu (II) was also achieved by the as-prepared electrode.

Electrochemistry with Ion Transfer Processes at Microhole-Liquid/Gel Interfaces for Sensing Applications

There have been extensive efforts made on developing highly sensitive and selective electrochemical sensing technologies for a wide spectrum of environmental, biological and food research applications. In this talk, we will discuss our latest achievements made on creating electrochemical sensing platforms composed of microhole supported-water/gel interfaces (micro-ITIES) for the highly selective and sensitive detection of environmentally toxic and pharmaceutical reagents. A single or an array of microholes fabricated on a thin polymer film (e.g., polyethylene terephthalate) was filled with a hydrophobic polyvinylchloride-nitrophenylocytylether (PVC-NPOE) gel to create microhole-ITIES. For example, a Cu(II) ion selective sensor was designed utilizing the assisted transfer reaction of Cu(II) by a novel Cu(II) selective ionophore, picolinamide-PV in the gel layer [1]. In addition, sodium, potassium and calcium selective sensing platforms incorporating each target selective ionophores in the gel was developed for ion analysis in biological fluids including urine, serum and plasma [2]; the concentration of each ions was determined by measuring the current associated with the transfer of Na+, K+ and Ca2+ across the microhole-ITIES assisted by dibenzo-18-crown-6, valinomycin and ETH-129, respecively. These sensors can also be fabricated on a disposable sensing chip platform for convenient field applications. Last example is the use of microhole-ITIES for developing selective sensing platforms for pharmaceutical drugs such as topotecan [3], doxorubicin, tetracycline, levofloxaxin in biological fluids and stream and river water samples. In order to enhance the sensitivity of the sensors, differential pulse stripping voltammetry was used via holding the transferring potential of each analytes for a certain time to enrich the target ions in the gel layer followed by stripping of the ions from the gel to water phase. Lastly, future aspects of microhole-ITIES for ion sensing applications will be discussed.

Sensitive determination of capsaicin on Ag/Ag2O nanoparticles/reduced graphene oxide modified screen-printed electrode

Ag/Ag2O-loaded poly(sodium4-styrenesulfonate) (PSS) functionalized reduced graphene oxide (rGO) composite (Ag/Ag2O-PSS-rGO) with high catalytic activity was synthesized for sensitive determination of capsaicin. The prepared composite was characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The obtained images revealed the good distribution of Ag/Ag2O on the PSS-rGO and confirmed the successful synthesis of the nanocomposite. Adsorptive stripping voltammetry (AdsSV) and differential pulse stripping voltammetry (DPSV) were used to study the electrochemical performance of the prepared sensor, and showed excellent electro-catalytic activity to the redox reaction of capsaicin due to the synergistic effect between Ag/Ag2O and PSS-rGO. Under the optimized conditions, the linear range of capsaicin was found to be 1.0–60μM with a detection limit of 0.40μM (S/N=3).

The Graphene/l-Cysteine/Gold-Modified Electrode for the Differential Pulse Stripping Voltammetry Detection of Trace Levels of Cadmium.

Cadmium(II) is a common water pollutant with high toxicity. It is of significant importance for detecting aqueous contaminants accurately, as these contaminants are harmful to human health and environment. This paper describes the fabrication, characterization, and application of an environment-friendly graphene (Gr)/l-cysteine/gold electrode to detect trace levels of cadmium (Cd) by differential pulse stripping voltammetry (DPSV). The influence of hydrogen overflow was decreased and the current response was enhanced because the modified graphene extended the potential range of the electrode. The Gr/l-cysteine/gold electrode showed high electrochemical conductivity, producing a marked increase in anodic peak currents (vs. the glass carbon electrode (GCE) and boron-doped diamond (BDD) electrode). The calculated detection limits are 1.15, 0.30, and 1.42 µg/L, and the sensitivities go up to 0.18, 21.69, and 152.0 nA·mm−2·µg−1·L for, respectively, the BDD electrode, the GCE, and the Gr/l-cysteine/gold electrode. It was shown that the Gr/l-cysteine/gold-modified electrode is an effective means for obtaining highly selective and sensitive electrodes to detect trace levels of cadmium.