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A personal mini-review is presented on the history of electroanalysis and on their present achievements and future challenges. The manuscript is written from the subjective view of two generations of electroanalytical chemists that have witnessed for many years the evolution of this discipline.

Following the great success of graphene as a versatile 2D nanomaterial for the design of electrochemical sensors, this review focuses on the synthesis, characterization, and electrochemical sensing applications of alternative 2D layered structures produced with elements of group VA, also known as “pnictogens.” Among these, phosphorene nanosheets generated from black phosphorous (BP) is by far the most popular 2D layered pnictogen; however, bismuthene and antimonene are also gaining interest in the design of electrochemical sensors. A perspective is given to the properties of the various layered pnictogens and factors affecting their stability, which also influence their sensing abilities. Examples using arsenene are still relatively sparse as this is not an attractive material for biosensing due to its acute toxicity. Tables with the most meaningful information from the available literature are presented.

A voltammetric electronic tongue was constituted by four screen-printed modified electrodes: a carbon nanofiber modified electrode, an ex-situ antimony film electrode prepared from carbon nanofiber modified electrode, and two carbon nanofiber electrodes chemically modified with Cys and GSH. The tongue was successfully applied to the analysis of a complex mixture of metal ions (4 analytes and 2 interferences) by differential pulse anodic stripping voltammetry. Each sensor was firstly studied for the determination of each metal separately confirming that all electrodes showed differentiated response for the metals. The obtained voltammetric signals provided by the sensor array were processed by Partial Least Squares regression (PLS) to resolve the overlapped nature of the obtained multimetal stripping measurements. This PLS model was built considering a hierarchical model in order to reduce the large amount of data. The method was applied to synthetic mixtures of Cd(II), Pb(II), Tl(I), and Bi(III) in the presence of Zn(II) and In(III) at the levels of μg L −1 and successfully validated with correlation coefficients of both calibration and prediction higher than 0.9 obtained from predicted vs. expected concentration graphs. Moreover, the simultaneous determination of Cd(II), Pb(II), Tl(I), and Bi(III) in the presence of Zn(II) and In(III) in a spiked tap water was also satisfactory achieved, providing comparable results to those obtained by ICP-MS.

A voltammetric electronic tongue has been designed as a proof of concept for the analysis of aminothiols by differential pulse voltammetry and has been tested in ternary mixtures of cysteine (Cys), homocysteine (hCys) and glutathione (GSH). It consists of three screen-printed electrodes of carbon, carbon nanofibers and gold cured at low temperature. A preliminary calibration study carried out separately for each aminothiol confirmed that, working at an optimal pH value of 7.4, every electrode produces differentiated responses for every analyte (cross-response). As for the tongue, it was applied to calibration and validation mixtures of Cys, hCys and GSH and provided voltammograms that, baseline-corrected, normalized and combined in different ways were submitted to partial least squares (PLS) calibration. The calibration models produced good predictions of the concentrations of all three analytes, which suggest that the proposed voltammetric tongue improves the performance of a previous design based on linear sweep voltammetric measurements under acidic conditions.

This work reports the development of a dimethylglyoxime (DMG) modified sensor in which the complexing agent was successfully immobilized by drop-casting onto a screen-printed carbon electrode support (SPCE). The experimental conditions for the preparation of the DMG-SPCE sensor were optimized by means of a D-optimal design, and the built sensors were analytically evaluated for the determination of Ni(II) by adsorptive stripping voltammetry (AdSV). Its analytical performance suggests its suitability for the determination of Ni(II)-ions by AdSV at concentration levels of μg L−1 (LOD of 2.3 μg L−1, linear range from 7.6 to 200 μg L−1). Finally, the applicability of the developed sensor was assessed by the determination of trace levels of Ni(II) by AdSV in a wastewater reference material with a very high reproducibility (0.005%) and good trueness (0.1%).

Some typical strategies of experimental design are reviewed and their applications to electroanalytical studies are illustrated with examples from the literature. The experimental designs considered are mainly based on the concepts of response surface and factorial design and are essentially applied for screening, optimization and calibration purposes.

A critical revision is made on recent applications of voltammetric electronic tongues in the field of food analysis. Relevant works are discussed dealing with the discrimination of food samples of different type, origin, age and quality and with the prediction of the concentration of key substances and significant indexes related to food quality.

The main characteristics of the data acquired with different electroanalytical techniques are discussed as essential knowledge for an adequate selection and application of the chemometric methods described in the rest of the monography.

Multivariate curve resolution (MCR) is discussed as a chemometric strategy to study the evolution of a system during a process by means of the analysis of multivariate data and the obtention of pure signals and concentration profiles. Although the chapter is focused on the alternating least squares (ALS) algorithm and their electroanalytical applications, other approaches are discussed for the analysis of non-linear data.

Two different modification strategies by means of aryl diazonium salt electrografting were compared for the development of voltammetric sensors. In this sense, l -cysteine was immobilized onto a screen-printed carbon-based electrode surface through either its –NH2 or its –COOH group and the performance of the resulting modified sensors was tested for the simultaneous determination of Pb(II) and Cd(II) by anodic stripping voltammetry. The results obtained indicate that attachment through the –COOH group of cysteine, despite being a much less frequent electrografting strategy, improves the analytical performance of the resulting sensor achieving lower LODs, at low μg L−1 levels, for Cd(II) and Pb(II). Furthermore, this strategy allows the quantification of both metal ions below the legal limits established by the European Water Framework Directive, which represents a great improvement with respect to similar sensors reported in the literature.

A critical revision is made on the main approaches and results arising from the combination of multivariate curve resolution by alternating least squares (MCR-ALS) and electroanalytical measurements in the field of environmental analytical chemistry. Although most of the work done has been focused on the study of the metal binding properties of metal bioregulators such as metallothioneins or phytochelatins, new perspectives appear in the evolving world of sensors for environmental monitoring.

The determination of Sb(III) on an ex-situ bismuth screen-printed carbon electrode (ex-situ BiSPCE) by means of adsorptive stripping voltammetry (AdSV) using quercetin-5′-sulfonic acid as chelating agent was optimized. The effect of different experimental parameters such pH, ligand concentration (CQSA), accumulation potential (Eacc) and accumulation time (tacc) were studied to obtain a wide linear range, the highest sensitivity and the lowest detection limit. Ex-situ BiSPCE was analytically compared with a sputtered bismuth screen-printed electrode (BispSPE) under optimal conditions. The obtained analytical parameters suggest that ex-situ BiSPCE behaves much better than BispSPE and the first was selected for this study. Optimal parameters were pH=4.6; CQSA=10.0 to 20.0×10−6 mol L−1; Eacc=−0.5 V and tacc=60 s. Peak area is proportional to Sb(III) concentration up to 100.0 μg L−1 (tacc 60 s) and 45.0 μg L−1 (tacc 120 s) range, with detection limits of 1.2 μg L−1 (tacc 60 s) and 0.8 μg L−1 (tacc 120 s). The relative standard deviation for a Sb(III) solution (20.0 μg L−1) was 3.9% for ten successive assays. Thus, the effect of various interfering metal ions was studied and the methodology was validated using a spiked groundwater reference material with very satisfactory results.

This review summarizes analytical determinations carried out using antimony film electrodes (SbFEs), an environmentally safe option that constitutes an alternative not only to the most conventional Hg-based electrodes but also to Bi-based electrodes. SbFEs offer some interesting characteristics such as favorably negative overvoltage of hydrogen evolution, wide operational potential window, convenient operation in acidic solutions of pH 2 or lower and a very small Sb stripping signal. The substrate on which the Sb was plated is used to classify the types of SbFEs. Moreover, we detail the method of coating the substrate with Sb as well as the Sb modifiers. We present tables with the most important information from the accessible literature.

This review summarizes the latest advances in the study of phytochelatins, which are thiol-rich peptides synthesized by plants, algae and fungi as a response to heavy-metal stress. We emphasize the use of analytical techniques to get complementary information about the binding of heavy-metal ions by these molecules. Such information is especially valuable to understand complexation mechanisms and to investigate the role of phytochelatins in heavy-metal detoxification. Among the techniques considered, reversed-phase liquid chromatography and size-exclusion chromatography with fluorimetric, atomic spectrometric, amperometric or mass spectrometry (MS) detection are essential for the analysis of natural extracts, whereas chemometrically-assisted voltammetry, isothermal titration calorimetry or direct-injection MS are key tools in binding studies carried out in synthetic mixtures of metal ions and phytochelatins. We present tables with the most significant information from recent literature (since 2000) and figures to illustrate some analytical methodologies and results.

A new multivariate standard addition strategy applicable to stripping methods was proposed as an extention of the classical univariate standard addition method for the resolution of complex samples involving overlapped peaks and complex matrices. The proposed strategy consists in alternate additions of the considered analytes and the further extrapolation to a simulated blank solution measured by skipping the preconcentration step (deposition time = 0). This calibration approach was successfully tested in tonic water samples spiked with Tl(I) and In(III) using a sensor array based on a SeCyst-SPCNFE and an ex-situ-BiSPCE, providing good concordance between replicates and much better accuracy than the usual multivariate external calibration method.

The development of a simple HPLC-UV method towards the evaluation of Spanish paprika&rsquo, s phenolic profile and their discrimination based on the former is reported herein. The approach is based on C18 reversed-phase chromatography to generate characteristic fingerprints, in combination with linear discriminant analysis (LDA) to achieve their classification. To this aim, chromatographic conditions were optimized so as to achieve the separation of major phenolic compounds already identified in paprika. Paprika samples were subjected to a sample extraction stage by sonication and centrifugation, extracting procedure and conditions were optimized to maximize the generation of enough discriminant fingerprints. Finally, chromatograms were baseline corrected, compressed employing fast Fourier transform (FFT), and then analyzed by means of principal component analysis (PCA) and LDA to carry out the classification of paprika samples. Under the developed procedure, a total of 96 paprika samples were analyzed, achieving a classification rate of 100% for the test subset (n = 25).

A multivariate version of the classical univariate standard addition method is tested as a proof of concept for the voltammetric analysis of complex samples generating overlapped signals in the presence of significant matrix effects. The proposed strategy applies a multivariate calibration method such as partial least squares (PLS) to the full voltammograms measured for the sample alone and after combined additions of a series of standard solutions (one for every analyte). Then, a calibration model is built and further applied to the prediction of the concentration added to a blank, i.e., a full voltammetric signal measured in the absence of analytes. The absolute value of such predicted concentration is taken as the concentration of the analyte in the sample. The method has been successfully tested in different natural water samples spiked with hydroquinone and catechol and appears to be a promising tool for the analysis of overlapped signals in complex matrices.

Potentiometric stripping analysis (PSA), also known as stripping chronopotentiometry (SCP), is an electroanalytical technique based on the accumulation either by electrolysis or by adsorption of the analyte on the electrode and its further stripping back to the solution mostly by oxidation in the presence of a chemical oxidant or by the application of a constant oxidation current (constant current stripping chronopotentiometry, SSCP). During the stripping step, the potential is registered as a function of time and defines transition times between steep potential changes. Such transition times are proportional to the concentration of the analytes being stripped from the electrode. PSA is especially useful for the analysis of samples with complex matrices involving large amounts of organic matter.

An Ex-situ antimony film screen-printed carbon electrode (Ex-situ SbSPCE) was successfully applied for the determination of Ni(II), by means of adsorptive stripping voltammetry using dimethylglyoxime as complexing agent, in a certified reference wastewater sample. This electrode is proposed as an alternative to more conventional antimony film electrodes. Ex-situ SbSPCE was analytically characterized and the obtained parameters suggest that Ex-situ SbSPCE behaves much better than both Ex-situ BiSPCE and BispSPE for Ni(II) determination. The results confirm the applicability of Ex-situ SbSPCE for the determination of low concentration levels of Ni(II) in natural samples with a very high reproducibility and good trueness.

For a long time mercury electrodes have been the main choice for the analysis of metal ions and some metalloids. However, in the last years, safety and environmental considerations have restricted their use and encouraged the search for alternative materials more environmentally friendly and with more possibilities for in-situ and flow analysis. This research has been reinforced by the popularisation of nanomaterials, biomolecules and screen-printed electrodes, as well as for the new advances in sensor miniaturization and integration of the electrodes in multi-sensor platforms and electronic tongues. The present review critically summarizes and discusses the progress made since 2010 in the development and application of new electrodes for the analysis of metals and metalloids.

This work deals with the development of screen-printed carbon electrodes modified with L-glutamic acid via two different approaches: electropolymerization (SPCE/PGA) and aryl diazonium electrochemical grafting (SPCE/EGA). SPCE/PGA and SPCE/EGA were analytically compared in the determination of hydrochlorothiazide (HCTZ) by differential pulse voltammetry. Both electrochemical characterization and analytical performance indicate that SPCE/EGA is a much better sensor for HCTZ. The detection and quantification limits were at the level of micromol L-1 with a very good linearity in the studied concentration range. In addition, the proposed SPCE/EGA was successfully applied for the determination of HCTZ in an anti-hypertensive drug with high reproducibility and good trueness.

A new silver nanoparticle modified screen-printed electrode was developed and applied to the simultaneous determination of Pb(II) and Cu(II). Two different types of silver nanoparticles with different shapes and sizes, Ag nanoseeds and Ag nanoprisms, were microscopically characterized and three different carbon substrates, graphite, graphene and carbon nanofibers, were tested. The best analytical performance was achieved for the combination of Ag nanoseeds with a carbon nanofiber modified screen-printed electrode. The resulting sensor allowed the simultaneous determination of Pb(II) and Cu(II) at trace levels and its applicability to natural samples was successfully tested with a groundwater certified reference material, presenting high reproducibility and trueness.

A sensor array consisting of a chemically modified sensor in which 4-carboxybenzo-18-crown-6 was immobilized onto a screen-printed carbon nanofiber-modified electrode (crown-6-SPCNFE) and an ex-situ antimony film deposited on a screen-printed carbon nanofiber-modified electrode (ex-situ-SbSPCNFE) was applied for the resolution of the strong overlapped signals resulting from the simultaneous determination of Tl(I) and In(III) by stripping voltammetry. A Partial Least Squares model was constructed and good calibration curves of predicted vs. expected concentrations of the considered metal ions, with correlation coefficients higher than 0.98 for both training and test sets, were obtained. These results provided by the sensor array were compared with those obtained by a single electrode. Moreover, this sensor array was successfully applied for the voltammetric determination of both Tl(I) and In(III) in tap water, providing comparable results to those obtained by ICP-MS measurements.

A method using commercially available sputtered bismuth screen-printed electrodes (BispSPE), as substitute to mercury electrodes, for the determination of trace Pb(II) and Cd(II) ions in drinking well water samples collected in a contaminated area in The Republic of El Salvador by means of differential pulse anodic stripping voltammetry (DPASV) has been proposed. The comparable detection and quantification limits obtained for both BispSPE and hanging mercury drop electrode (HMDE), together with the similar results with a high reproducibility obtained in these water samples analyses recommend the applicability of BispSPE for the determination of low level of metal concentrations in natural samples.

For the first time, the suitability of bismuth bulk rotating disk electrode (BiB-RDE) for the study of metal complexation has been tested. Cyclic (CV) and differential pulse (DPV) voltammetry have been used to study the complexation of Pb(II) with two of the most effective chelating agents for the treatment of Pb(II) poisoning (meso-2,3-dimercaptosuccinic acid, DMSA, and 2,3-dimercapto-1-propanesulfonic acid, DMPS). Multivariate curve resolution has been applied to voltammetric data to obtain the stoichiometries and stability constants of the complexes formed. In both systems, the ML2 complex was predominant, with log β2 values of 10.13 and 8.80 for DMSA-Pb(II) and DMPS-Pb(II), respectively.

In order to show the possibilities of screen-printed electrodes in HPLC detection, a method is presented for routine quantification of aminothiols in human plasma. It uses commercial gold screen-printed electrodes and provides a rapid, simple and economical procedure with a disposable detector and without any additional electrode. By working at 98 : 2 (0.05 % trifluoroacetic acid: methanol) and 0.9 V, it allows us to determine cysteine (Cys), cysteinyl-glycine (Cys-Gly), and homocysteine (HCys) at μmol/L levels. The method was validated, and linearity range, detection and quantification limits, precision and accuracy were evaluated by external calibration and by using N-acetylcysteine as internal standard, which exhibited better precision.

A commercially available sputtered bismuth screen-printed electrode (BispSPE) has been pioneeringly applied for the simultaneous determination of Cd(II) and Pb(II) ions in a certified groundwater sample by means of differential pulse anodic stripping voltammetry (DPASV) as an alternative to more conventional bismuth screen-printed carbon electrodes (BiSPCEs). BispSPEs can be used for a large set of measurements without any previous plating or activation. The obtained detection and quantification limits suggest that BispSPEs produce a better analytical performance as compared to In-situ BiSPCE for Pb(II) and Cd(II) determination, but also to Ex-situ BiSPCE for Cd(II) determination. The results confirm the applicability of these devices for the determination of low level concentrations of these metal ions in natural samples with very high reproducibility (0.7% and 2.5% for Pb(II) and Cd(II) respectively), and good trueness (0.3% and 2.4% for Pb(II) and Cd(II) respectively).

Several parameters related to metal stress have been studied in Hordeum vulgare plants treated with Cd and Hg at different doses to provide new insights concerning toxicity and resistance mechanisms produced by these metals. To the best of our knowledge, for the first time the simultaneous stress by Hg and Cd has been investigated. Growth inhibition has been evaluated showing clear symptoms of phytotoxicity in metal stressed plants. Hg and Cd content evidenced the ability of this plant species to uptake and accumulate toxic metals in its tissues. Moreover, when both metals were present, regardless of their concentration, a lower uptake of Hg was observed leading us to conclude that Hordeum vulgare plants have less affinity for Hg when there is cadmium competing in the media. To explore a way of following toxic metal stress response in plants, HPLC with amperometric detection has been used to study different thiols: gluthatione (GSH), its fragments and several phytochelatins (PC2–5). The accumulation mecha...

The use of an antimony film coated on a screen-printed carbon electrode (ex-situ SbSPCE) is proposed for the determination of Pd(II) at ppb levels in natural samples by adsorptive stripping voltammetry using dimethylglyoxime as chelating agent. Ex-situ SbSPCE produces a better analytical performance as compared to a commercially sputtered bismuth screen-printed electrode (BispSPE). The detection and quantification limits were 2.7 and 9.0 µg L−1 respectively with a good linear behaviour in the wide examined concentration range (from 1 µg L−1 up to 100.0 µg L−1, R2=0.998). The proposed ex-situ SbSPCE showed an excellent repeatability with a relative standard deviation of 0.5% for ten successive measurements and a very good reproducibility (1.6% for three different ex-situ SbSPCE units within series of ten repetitive assays). Moreover, the ex-situ SbSPCE was successfully applied for the determination of low concentration levels of Pd(II) in spiked tap water with a very high reproducibility (0.2%) and providing equivalent results to those achieved by ICP-MS measurements.

The bismuth-coated screen-printed electrode is shown to be a suitable and safe alternative to the classical mercury electrode in the voltammetric determination of quinine in tonic water. This experiment is appropriate for undergraduate analytical courses as it helps students understand the fundamentals of electroanalysis using preplated screen-printed electrodes and the importance of green electrochemistry. Student interest is piqued by using a familiar real-world sample, tonic water.

This review summarizes analytical determinations using bismuth screen-printed electrodes (Bi-SPEs). We emphasize fundamental understanding of the design and the fabrication of these economical disposable sensors that are environment friendly. The methods of coating the Bi on the working surface and their potential modifications are used to classify the types of Bi-SPE. We present tables with the most significant information from the accessible literature.

This work reports the development of a glutathione modified electrode via electrografting on a screen-printed carbon nanofiber substrate (GSH-SPCNFE). GSH-SPCNFE was compared to a classical screen-printed carbon electrode modified with glutathione (GSH-SPCE) for the simultaneous voltammetric determination of Cd(II) and Pb(II). Their electrochemical characterization and analytical performance suggest that SPCNFE could be a much better support for GSH immobilization. The applicability of GSH-SPCNFE for the determination of low concentration levels of Pb(II) and Cd(II) ions in environmental samples was successfully tested in a certified wastewater reference material by means of stripping voltammetry with a very high reproducibility and good trueness.

Catechol (CC), resorcinol (RC) and hydroquinone (HQ) are dihydroxybenzene isomers that usually coexist in different samples and can be determined using voltammetric techniques taking profit of their fast response, high sensitivity and selectivity, cheap instrumentation, simple and timesaving operation modes. However, a strong overlapping of CC and HQ signals is observed hindering their accurate analysis. In the present work, the combination of differential pulse voltammetry with graphene screen-printed electrodes (allowing detection limits of 2.7, 1.7 and 2.4 μmol L-1 for HQ, CC and RC respectively) and the data analysis by partial least squares calibration (giving root mean square errors of prediction, RMSEP values, of 2.6, 4.1 and 2.3 for HQ, CC and RC respectively) has been proposed as a powerful tool for the quantification of mixtures of these dihydroxybenzene isomers. The commercial availability of the screen-printed devices and the low cost and simplicity of the analysis suggest that the proposed method can be a valuable alternative to chromatographic and electrophoretic methods for the considered species. The method has been applied to the analysis of these isomers in spiked tap water.

A voltammetric sensor array (or electronic tongue) is developed for the simultaneous quantification of cysteine, glutathione and homocysteine without need of previous separation. It is based on the integration of three commercial screen-printed electrodes (gold curated at high and low temperature and carbon modified with carbon nanotubes). Linear sweep voltammograms measured simultaneously by all three sensors are processed by Partial Least Squares (PLS) regression and different variables selection algorithms such as Genetic Algorithm and interval-Partial Least Squares. The method was applied to synthetic mixtures and successfully validated, with correlation coefficients of prediction (Rp2) of 0.9542, 0.9429 and 0.9589 for cysteine, glutathione, and homocysteine respectively.

A new multivariate curve resolution method is proposed according to the parametric signal fitting (PSF) strategy for the analysis of overlapping and highly asymmetric voltammetric signals. The method is based on the fitting of the well-known exponentially modified Gaussian (EMG) function, which had been previously used for the resolution of coeluted chromatographic peaks. The main advantage of this function is that one of the adjustable parameters is just the area under the peak, which is a magnitude more reliable than the peak height in the case of electrochemical systems providing highly asymmetric voltammograms. After a preliminary test with simulated data, the proposed method has been successfully applied to the experimental system Cd(II)–cysteine in both mercury and carbon screen-printed electrodes.

A new approach is presented to apply the classical equations of direct current and normal pulse polarography of irreversible processes to the multivariate data generated in voltammetric titrations of mixtures of complexes which are irreversibly reduced. For this purpose, the well known complexes of Pb(II) and Cd(II) with nitrilotriacetate (NTA) systems are considered. The proposed methodology is based on least-squares fitting and can be applied for a fixed time at different metal-to-ligand ratios and in a time-dependent way, which involves the fitting of current vs. potential vs. time matrices. In both cases, consistent and realistic results are obtained, thus suggesting the potential usefulness of this approach for more involved systems.

A recently developed methodology, which combines voltammetry, ITC, ESI-MS and several chemometric tools, has been applied for the first time to the study of As(III) complexes. The ligands considered, DMSA and DMPS, are commonly used to treat heavy metal poisoning. The study yields a reliable and consistent picture of the binding of As(III) by the chelating therapy agents DMSA and DMPS providing an unambiguous description of the stoichiometries of the complexes (ML(2), with the occasional appearance of ML in the case of DMSA), both ligands have stability constants of the same order, with a logβ(2) of 9.2 and 9.8, respectively. These values confirm the potential efficiency of both ligands in the treatment of As(III) poisoning.

The competitive binding of Cu2+, Cd2+ and Pb2+ in ternary mixtures by the phytochelatins PC2 and PC5 (PCn; (γGlu-Cys)n-Gly, n=2 and 5) are examined by voltammetry, which allows one to follow the displacements of the voltammetric signals induced by the competitive binding among the metal ions towards PC2 or PC5 complexation, and direct injection positive-mode Electrospray Ionization Mass Spectrometry (ESI-MS), in order to obtain the stoichiometries of the complexes. Voltammetric data are analyzed by Gaussian Peak Adjustment (GPA), which is a recently developed multivariate analysis method for nonlinear electrochemical data. Different complexes have been detected or deduced their presence, depending on the experimental conditions. Ternary complexes CuCdPCn and CdPbPCn were detected for both PC2 and PC5, while the ternary CuPbPCn complex was only detected for PC2. Some of the complexes have been only detected by ESI-MS because in some cases voltammetry data could not be totally resolved, even by using GPA. The quaternary CdPbCuPCn complex has been detected for PC5, but for PC2 data are not so conclusive. In summary, the signal evolution for mixed CdCuPCn complexes is quite different. These observations could be a reflection of an antagonistic effect for the case of PC2 and a synergetic one for PC5.

A new penicillamine-GCE was developed based on the immobilization of d-penicillamine on aryl diazonium salt monolayers anchored to the glassy carbon electrode (GCE) surface and it was applied for the first time to the simultaneous determination of Cd(II) and Pb(II) ions by stripping voltammetric techniques. The detection and quantification limits at levels of µg L(-1) suggest that the penicillamine-GCE could be fully suitable for the determination of the considered ions in natural samples.