Square Wave Voltammetry Method Research Articles

MCNTs/ZnO nanocomposite-fabricated nanosensor for 1-naphthyleacetic acid electroanalysis and its applications

Zinc oxide nanoparticles and multiwalled carbon nanotubes were mixed to create a novel carbon paste electrode known as MCNTs/ZnO/CPE—a substance that stimulates plant growth. This electrode was designed to investigate the effects of NAA. Various techniques, including cyclic voltammetry (CV) and square wave voltammetry (SWV), were employed to assess the stability and electrochemical properties of the MCNTs/ZnO/CPE electrode. The study aimed to examine the electrochemical behavior of NAA on MCNTs/ZnO/CPE to investigate its potential application in plant development. The experiment results provided valuable insights into the complementary effects of NAA and the electrode materials, paving the way for future advances in plant bioelectrochemistry. At a pH of 3.0, the more significant peak current indicates the effective electron transfer between the PB solution and the MCNTs/ZnO/CPE sensor. The sensor's outstanding catalytic activity at this pH further suggests its potential for various electrochemical applications. Actual samples, such as water, fruits, vegetables, and soil, were analyzed using the SWV method. ZnO/CPE, bare CPE, MCNTs/CPE, and MCNTs/ZnO/CPE all had peak currents of 4.044 µA, 10.40 µA, 12.91 µA, and 16.52 µA, respectively. The peak potentials for bare CPE, ZnO/CPE, MCNTs/CPE, and MCNTs/ZnO/CPE were all found to be 1.19 V, 1.19 V, 1.18 V, and 1.15 V, respectively. All the experiments were carried out at 25 s of optimum accumulation time. The detection limit was determined to be 1.1 nM, and the linear range is 0.2 × 10−8 to 7.0 × 10−6 M. The surface area of the unmodified CPE was determined to be 0.04 cm2, whereas the surface area of the modified CPE was determined to be 0.13 cm2. The mean value of the rate constant (ks) for the anodic reaction was 2.8 × 10−3 cm s−1. In addition to electro-kinetic factors like the effect of temperature and the heterogeneous rate constant, the electro-oxidation of NAA was examined about several parameters, including electron contribution, accumulation duration, pH, energy of activation, scan rate, and transfer coefficient.

Electrochemical biosensor for the evaluation of monoclonal antibodies targeting the N protein of SARS-CoV-2 virus

The emergence of COVID-19 caused by the coronavirus SARS-CoV-2 has prompted a global pandemic that requires continuous research and monitoring. This study presents a design of an electrochemical biosensing platform suitable for the evaluation of monoclonal antibodies targeting the SARS-CoV-2 nucleocapsid (N) protein. Screen-printed carbon electrodes (SPCE) modified with gold nanostructures (AuNS) were applied to design a versatile and sensitive sensing platform. Electrochemical techniques, including electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), were used to investigate the interactions between immobilised recombinant N (rN) protein and several monoclonal antibodies (mAbs). The electrochemical characterisation of SPCE/AuNS/rN demonstrated a successful immobilisation of rN, enhancing the electron transfer kinetics. Affinity interactions between immobilised rN and four mAbs (mAb-4B3, mAb-4G6, mAb-12B2, and mAb-1G5) were explored. Although mAb-4B3 showed some non-linearity, the other monoclonal antibodies exhibited specific and well-defined interactions followed by the formation of an immune complex. The biosensing platform demonstrated high sensitivity in the linear range (LR) from 0.2 nM to 1 nM with limits of detection (LOD) ranging from 0.012 nM to 0.016 nM for mAb-4G6, mAb-12B2, and mAb-1G5 and limits of quantification (LOQ) values ranging from 0.035 nM to 0.139 nM, as determined by both EIS and SWV methods. These results highlight the system's potential for precise and selective detection of monoclonal antibodies specific to the rN. This electrochemical biosensing platform provides a promising route for the sensitive and accurate detection of monoclonal antibodies specific to the rN protein.

Label-free electrochemical cancer cell detection leveraging hemoglobin-encapsulated silver nanoclusters and Cu-MOF nanohybrids on a graphene-assisted dual-modal probe

Breast cancer detection at an early stage significantly increases the chances of successful treatment and survival. This study presents an electrochemical biosensor for detecting breast cancer cells, utilizing silver nanoclusters encapsulated by hemoglobin and Cu (II)-porphyrin-metal organic framework (BioMOF) in a graphene-incorporated nanohybrid probe. This Hb-AgNCs@MOF-G probe demonstrates high electrochemical activity, superior dispersity, porosity, and a large surface area for effective functionalization. Using a green ultrasonic-assisted stirring method, we fabricate ultra-small 5 nm particles that readily immobilize on a glassy carbon electrode, generating a detection signal when interacting with ferricyanide/ferrocyanide redox probes. The resulting immunosensor detects as few as 2 cells/mL using Electrochemical Impedance Spectroscopy (EIS) “signal on” and 16 cells/mL via Square Wave Voltammetry (SWV) “signal off”, within a broad range of cell concentrations (102–5 × 104 cells/mL). Our designed sensor shows improved selectivity (5- to 16-fold) and robust detection in human blood with a recovery efficiency between 94.8–106% (EIS method) and 95.4–111% (SWV method). This sensor could streamline early cancer diagnosis and monitor patient treatment without requiring labelling or signal amplification. As a pioneering endeavor, we've utilized integrated porous MOFs with Hb-encapsulated silver nanoclusters in cancer detection, where these components collectively enhance the overall functionality.

Novel disposable and portable 3D-printed electrochemical apparatus for fast and selective screening of 25E-NBOH in forensic samples

The advent of new psychoactive substances (NPS) has caused enormous difficulty for legal control since they are rapidly commercialized, and their chemical structures are routinely altered. In this aspect, derivatives phenethylamines, such as 25E-NBOH, have received great attention in the forensic scenario. Hence, we propose portable and cost-effective (U$ 5.00) 3D-printed devices for the electrochemical screening of 25E-NBOH for the first time. The cell and all electrodes were printed using acrylonitrile butadiene styrene filament (insulating material) and conductive filament (graphite embedded in a polylactic acid matrix), respectively, both by the fused deposition modeling (FDM) 3D printing technique. The electrochemical apparatus enables micro-volume analysis (50–2000 μL), especially important for low sample volumes. A mechanistic route for the electrochemical oxidation of 25E-NBOH is proposed based on cyclic voltammetric data, which showed two oxidation processes around +0.75 V and +1.00 V and a redox pair between +0.2 and −0.2 V (vs. graphite ink pseudo-reference). A fast and sensitive square-wave voltammetry method was developed, which exhibited a linear working range from 0.85 to 5.1 μmoL−1, detection limit of 0.2 μmol L−1, and good intra-electrode precision (n = 10, RSD <5.3 %). Inter-electrode measurements (n = 3, RSD <9.8 %) also attested that the electrode production process is reproducible. Interference tests in the presence of other drugs frequently found in blotting paper indicated high selectivity of the electrochemical method for screening of 25E-NBOH. Screening analysis of blotting paper confirmed the presence of 25E-NBOH in the seized samples. Moreover, a recovery percentage close to 100 % was found for a spiked saliva sample, suggesting the method's usefulness for quantitative purposes aimed at information on recent drug use.

Development of square wave voltammetry method using working electrodes modified with nickel oxide and carbon black for determination of 5-hydroxymethylfurfural in honey

This work describes the development of a novel square wave voltammetry (SWV) method for the rapid and sensitive quantification of 5-hydroxymethylfurfural (HMF) in honey samples. The method employs a combination of nickel oxide and carbon black (NiO-CB) to modify lab-made screen-printed carbon electrodes (SPCEs). The adaptability of the NiO-CB/SPCE enables its potential application in detecting HMF based on electrochemical reduction, which eliminates the need for sample extraction and streamlines the analysis process. The developed SWV method exhibits suitable working ranges of 0.5–10.0 mg kg−1 for HMF in the buffer and 10.0–200.0 mg kg−1 for HMF in honey, achieving accurate and precise measurements with a limit of detection (LOD) and limit of quantification (LOQ) of 5.4 and 18.0 mg kg−1, respectively. The exceptional specificity of the developed method towards HMF is confirmed by its negligible response to interfering substances commonly found in honey. Furthermore, a comparative study between the developed SWV and the standard high-performance liquid chromatography (HPLC) methods reveals a strong correlation and no significant difference in the results obtained. Hence, the innovative electrochemical method can be utilized as an alternative method for rapidly quantifying HMF in honey samples.

Fast Screening Test of Apple Juice and Surface Water for Patulin Recognition and Quantification

Since a high concentration of patulin causes cytotoxicity, a new approach to the determination of patulin plays an important role in the research and development of new control technologies. The main objective of the paper is to provide a fast screening method for obtaining clean water and high-quality apple juice. Square-wave voltammetry method using a modified Mn (OAP) Cl screen-printed carbon electrode was used for the fast screening test of apple juice and surface water for patulin recognition and quantification. A number of experimental parameters, such as scan rate, type of buffer solution, and pH, were studied and optimized. Thus, a linear concentration dependence was determined in the range 1.00 × 10–12 to 1.00 × 10–8 mol L–1, while the quantification limit was 1.00 × 10–12 mol L–1 and the detection limit was 3.33 × 10–13 mol L–1. High reliability was achieved at the assay of patulin in water and apple juice samples, with a recovery rate of 96.27–99.88%, relative standard deviation (RSD), and a bias value of less than 5.00%. Based on the remarkable outcomes, it can be inferred that the sensor holds promise as a robust instrument for point-of-care detection in the times ahead.

A disposable electrochemical sensor based on single-walled carbon nanotubes for the determination of anticancer drug dasatinib

Dasatinib is an anticancer drug that treats acute lymphoblastic leukemia, chronic myelogenous leukemia, and prostate cancer with several side effects. In this research, we suggest nanoparticle-modified screen-printed electrodes (SPCEs) as disposable electrochemical sensors for fast quantification of dasatinib in pharmaceutical formulations. Carbon nanotubes, single-walled carbon nanotubes (SWCNT), graphene, and graphene oxide-modified SPCEs were characterized by scanning electron microscopy. The study also recommends SWCNT-modified SPCEs as the best-performing electrode for determining dasatinib, demonstrating an excellent boosting effect on the oxidation response of dasatinib. This was accomplished using the square-wave voltammetry method. After optimization of the pH condition, pH 5.0 Britton–Robinson buffer, SWCNT-modified SPCEs demonstrated 94% recovery with optimum electro-oxidation activity. The oxidation currents exhibited linear relation with dasatinib concentration in the 0.1–100 µM. Based on the results, a limit of detection of 0.06 µM was obtained in the standard solution. The SWCNT-modified SPCEs have been applied to analyze dasatinib in pharmaceutical tablet samples. The demonstrated performance beats all comparable standard analytical tools and presumably may be used for general drug quantitation in pharmaceutical tablets.Graphical abstract

Electroanalytical Analysis of Guaifenesin from Pharmaceuticals on Boron Doped Diamond Electrode

The expectorant drug guaifenesin (GFN) electroanalytical analysis was performed on boron doped diamond electrode (BDDE) by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV) methods. The results of CV studies indicate that the reaction mechanism of GFN in the oxidation direction on the BDDE is irreversible and diffusion controlled. The linearity ranges are 0.400 ˗ 100 µM and 0.800 ˗ 100 µM for DPV and SWV methods, respectively. Limit of detection (LOD) values are obtained as 1.47 nM for DPV and 2.92 nM for SWV. Quantitative analysis of GFN from the pharmaceuticals was performed with fully validated DPV and SWV methods without any pre-separation. The sensitive methods with good recovery, high precision and accuracy have been developed for the electroanalytical analysis of GFN.

Electrochemical Sensors Based on Flexible Laser-Induced Graphene for the Detection of Paraquat in Water

Paraquat (PQ) is known to be highly toxic among herbicides and harmful to human health upon exposure because it causes various kinds of organ failure and affects the nervous system. Nowadays, increasing concentration of PQ in water bodies is a growing concern among many countries. On-site-based detection is very needed along with selectivity and sensitivity, which can be achieved through an electrochemical-based sensor. In this paper, a flexible laser-induced graphene (LIG)-based electrode was developed for the effective detection of PQ by the electrochemical square-wave-voltammetry (SWV) method. LIG is a 3D porous material fabricated by patterning with the help of CO2 laser irradiation on polyimide (PI) films and has extensive properties such as high conductivity, biocompatibility, and high porosity. LIG was further treated in a phosphate buffer solution to obtain treated LIG (t-LIG). The surface morphology and carbon fingerprint of both LIG and t-LIG were then characterized using scanning electron microscopy (SEM) and Raman spectroscopy, where SEM images have shown a more exposed porous structure in t-LIG. Electrochemical characterization was carried out using cyclic voltammetry and revealed a good current response and more surface activation of t-LIG over LIG. The detection of PQ carried out using t-LIG by the SWV method showed a high linear range of 0.5–35 μM with a sensitivity of 46.6 μA μM–1 cm–2 and a limit of detection of 0.54 μM. t-LIG has shown a very good average recovery rate of PQ when spiked in real water samples of 96.6%.

In situ electrodeposition of bismuth oxide nanowires @MWNT on the carbon fiber microelectrode for the sensitively electrochemical detection of folic acid

A microminiaturized electrochemical device, BiO@CNW/CFE was fabricated based on the in situ co-electrodeposition of bismuth oxide nanowires (BiNWs) and multi-walled carbon nanotubes (MWNTs) on the surface of carbon fiber electrode (CFE). The nanostructure of BiNWs could bind MWNTs on the surface of CFE during the precipitation of bismuth at the potential of −1.1 V. The vimineous nanostructure of BiO@CNW improved the surface area and electrochemical activity of the microelectrode. With the low background noise, folic acid (FA) can be detected sensitively by BiO@CNW/CFE based on the electrochemical reduction via the method of square wave voltammetry. The linear range of FA in sodium acetate-acetic acid buffer was achieved in the range of 5.00 nM–200 nM, the detection limit was estimated to be 0.63 nM. The recoveries of FA in human serum and artificial cerebral spinal fluid were between 99% and 103%, which indicates BiO@CNW/CFE was a reliable sensor for the detection of FA in biological samples.

Design and fabrication of electrochemical sensor based on molecularly imprinted polymer loaded onto silver nanoparticles for the detection of 17-β-estradiol.

In this research report, we prepared an electrochemical sensor based on the molecularly imprinted poly(p-aminophenol) supported by silver nanoparticles capped with 2-mercaptobenzoxazole for the selective and sensitive detection of endocrine disrupting 17-β-estradiol (E2). The electropolymerization of the functional monomer prepared the proposed molecularly imprinted polymer (MIP) composite-based sensor in the presence of E2 as a template. The recognition materials were characterized using Fourier transform infrared, cyclic voltammetry (CV), square wave voltammetry (SWV), scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray powder diffraction techniques. The electrochemical measurements were performed by employing both CV and SWV methods. We did the optimization of critical parameters affecting the sensor performances through the experimental design and verification. The developed sensor showed a linear range from 10 pM to 100 nM with the calculated quantification and detection limits of 1.86 and 6.19 pM, respectively. The incorporation of AgNP with high electrical conductivity into the MIP matrix enhanced the sensor's performance. Furthermore, the sensor was applied to determine E2 in real water samples without any sample preconcentration steps to achieve the percent recovery of 91.87% to 98.36% and acceptable reusability and storage stability performances.

Emphasis on the incorporation of Tropaeolin OO dye and silver nanoparticles for voltammetric estimation of flibanserin in bulk form, tablets and human plasma

A novel electrochemical sensor based on the electro-deposition of silver nanoparticles (AgNPs) on Tropaeolin OO (poly-TO) layers over pencil graphite electrode (PGE) surface was fabricated for the first time for voltammetric determination of flibanserin (FBS); a drug enhances female sexual performance. Further characterization studies using cyclic voltammetry (CV), square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were conducted. The AgNPs synergistic effect on poly-TO layers facilitates the FBS electro-oxidation in phosphate buffer solution (pH 6.0) and its determination in bulk form, tablets and in human plasma. Following ICH guidelines, validation of the proposed SWV method for FBS analysis was successfully achieved using the fabricated sensor (AgNPs@poly-TO/PGE). Under the optimal instrumental and experimental conditions, the anodic oxidation peak current was directly proportional to FBS concentration in the range from 0.1 to 8.5 μmol L−1 with low detection and quantitation limits (0.0286 and 0.0867 μmol L−1, respectively). High sensitivity, selectivity as well as easiness of fabrication are the main advantages of the modified sensor.

Electro-analytical sensing of anti-hypotensive agents: application to dosage forms and human urine.

A new and valid method was developed for the quantitative voltammetric analysis of midodrine hydrochloride (MID) in pharmaceutical tablets (Midodrine) and biological samples. The method is based on electro-oxidation of MID supported by both disposable pencil electrode (PE) and glassy carbon electrode (GCE). The analysis was carried out using cyclic voltammetry, differential pulse voltammetry (DPV), and square wave voltammetry (SWV) techniques. The proposed analytical method was validated according to ICH guidelines. MID was successively assayed at concentration ranges of 1.15-6.55 and 0.58-3.05μgmL-1 at PE. Also, MID was successively assayed at concentration ranges of 1.15-5.28 and 2.86-27.6μgmL-1 at GCE for DPV and SWV methods, respectively. The proposed method was successfully used for the analysis of MID in its dosage form and human urine with good recoveries of 99.66±0.33, 99.8±0.45 at PE and 99.8±0.25, 98.7±1.27 at GCE for the DPV and SWV methods, respectively. The suggested method could be applied to the studied drug in the quality control lab as well as in its pharmacokinetic studies.

Simultaneous Determination of Amlodipine and Irbesartan in their Pharmaceutical Formulations by Square-Wave Voltammetry.

Hypertension is one of the most important health problems in the world and irbesartan and amlodipine are used in combination in various dosages for the treatment of high blood pressure. The aim of this study is to develop a fast, easy, sensitive, accurate, and precise squarewave voltammetry method for simultaneous determination of irbesartan and amlodipine besylate from pharmaceutical formulations at a hanging mercury drop electrode. In the applied method, since both active substances gave a peak at different potentials, no interference occurred between them. In optimization studies, Britton-Robinson buffer of pH 8.0 was chosen, in which the most appropriate peak shape and maximum peak current were observed. At the same time, as a result of instrumental parameter optimization to obtain reproducible results, 6 mV for scan increment, 30 mV for pulse amplitude, and 50 Hz for frequency were found suitable. As a result of the calibration studies of the optimized method, linear working ranges were determined as 1.00-13.08 μg mL-1 for irbesartan and 5.83-16.51 μg mL-1 for amlodipine besylate. Limit of detection and limit of quantitation values were respectively calculated as 0.63 and 1.00 μg mL-1 for irbesartan and 0.50 and 1.98 μg mL-1 for amlodipine besylate. The results of precision values (RSD) ranged from 0.67% to 2.31% for irbesartan and 0.65% to 1.49% for amlodipine besylate. Accuracy values were calculated as -0.15% to 1.63% for irbesartan and -0.07% to 3.78% for amlodipine besylate. The results obtained from the recovery studies ranged from 101.05% to 102.78% and from 98.88% to 102.20% for amlodipine besylate and irbesartan, respectively. After the validation studies of the developed method were carried out, it was successfully applied to pharmaceutical formulations containing these active substances.

Electrochemical determination of (S)-7-hydroxywarfarin for analysis of CYP2C9 catalytic activity

An electrochemical method for the quantitative determination of (S)-7-hydroxywarfarin as a metabolite of the vitamin K antagonist warfarin has been developed to analyze the catalytic activity of cytochrome P450 2C9 (CYP2C9). The electrochemical properties of (S)-7-hydroxywarfarin were investigated using screen-printed carbon electrodes. We have shown by cyclic voltammetry that irreversible (S)-7-hydroxywarfarin electrochemical oxidation, in contrast to (S)-warfarin, can be registered by an oxidation peak at approximately 0.6 V (vs. Ag pseudo-reference electrode). A linear dependence of the oxidation peak amplitude in the range of 0.57–0.61 V on (S)-7-hydroxywarfarin concentration (in the range of 0.1–1 μM) was shown by the square-wave voltammetry method. The limit of (S)-7-hydroxywarfarin detection and the sensitivity were calculated as 0.091 μM and 0.0075 A/M, respectively. Using an electrochemical system based on recombinant human CYP2C9 immobilized on screen-printed carbon electrodes modified by didodecyldimethylammonium bromide, we have shown the possibility of (S)-7-hydroxywarfarin electrochemical quantification without separation of the enzymatic system component. The (S)-7-hydroxywarfarin quantitative electrochemical determination was used to calculate the kinetic parameters of CYP2C9 immobilized on electrode toward (S)-warfarin: the values of the maximal reaction rate (Vmax) and the Michaelis constant (KM) were calculated as 0.1 ± 0.002 min−1 and 3.03 ± 0.38 μM, respectively. The usage of an enzymatic CYP2C9-containing electrode as a catalyst and an indicator electrode as a sensor for the formation of metabolite allows to effectively register the kinetic parameters of the process. Such a two-electrode system can be applied to assess drug-drug interactions.

Synthesis of ZnO nanoparticles on carbon graphite and its application as a highly efficient electrochemical nano-sensor for the detection of amoxicillin:analytical application: milk, human urine, and tap water

Amoxicillin is an antimicrobial of the penicillin class discovered in 1928. The objective of this paper is to construct a simple platform for electrocatalytic detection of amoxicillin using a ZnO@CPE nano-sensor constructed using simple and inexpensive processes using hydrothermal methods. Our results show that the constructed ZnO@CPE electrode exhibits excellent electrocatalytic activity compared to the unmodified electrode, with consistent, reproducible, and stable behavior. The electrochemical behavior of the amoxicillin oxidation reaction is diffusion controlled and fully reversible. The effect of the pH of the phosphate buffer solution on the antibacterial behavior of amoxicillin shows that the number of protons and electrons were equal. The morphology and chemical composition of the constructed nanoparticles were characterized by scanning electron microscope, transmission electron microscope, high-resolution transmission electron microscope, X-ray diffractometer, and infrared spectroscopy. Suggest the formation of zinc oxide nanocrystals on the carbon sheets with an order size of 22.957 nm. The diffusion coefficient and catalytic rate constant were 1.135 × 10–4 cm2/s and 8.314 × 103 mol.l−1/s, respectively. The proposed nano-sensor demonstrated a wide linearity range from 10–4 M to 10–6 M with LOD = 1.21 × 10–7 M and LOQ = 3.32 × 10–7 M according to the square-wave voltammetry method. The ZnO@CPE nano-sensor was examined for the detection of amoxicillin in real samples. Schematic concept of amoxicillin detection on the electrocatalytic surface of the nano-sensor fabricated with ZnO@CPE.

Electrochemical determination of melatonin using disposable self-adhesive inked paper electrode

Melatonin is a hormone that affects sleep-wake cycles and plays a role in the understanding of neuronal disorders and has excellent potential for therapeutical applications in infectious diseases, becoming an important target of chemical analysis. In this context, we report the development of an electrochemical device comprising a self-adhesive electrode based on a graphite-automotive varnish (Gr-AV) mixture as a conductive material to produce a printable ink applied over a paper adhesive easily transferred to a polyethylene terephthalate substrate. The Gr-AV electrode presented a high electrochemically active surface area which showed to be suitable for melatonin oxidation. The association of the device alongside a square-wave voltammetry method offered a linear behavior in the concentration range from 10.0 to 100.0 µmol L−1, a limit of detection of 0.49 µmol L−1, as well as presenting exciting recovery and relative standard deviation over samples analysis. The results showed the valid application of the device for the determination of melatonin in biological samples, pharmaceutical formulations, and its potential for point-of-care analysis.

Electrochemical determination of boron using the signal suppression of mannitol on a gold nanoparticle coated p-Aminothiophenol polymer electrode

In this study, a glassy carbon electrode (GCE) modified with gold nanoparticles (AuNPs) and coated with electropolymerized p-aminothiophenol (p-ATP) was used as a modified electrode (GC/AuNPs/PATP electrode) for the indirect electrochemical determination of boron (B) using boric acid-mannitol complexation. The developed electrode showed good electroactivity for B determination. Firstly the current intensity of mannitol was measured, then B (as H3BO3) was added to the medium and the unreacted mannitol was measured. The decrement in current intensity was recorded against B concentration to build linear calibration curves within the range of 5–50 mg L−1 of B using square wave voltammetry (SWV), and the oxidation peak potential of mannitol was observed at 0.97 V. The limit of detection (LOD) and limit of quantification (LOQ) were 1.43 mg L−1 and 4.77 mg L−1, respectively. Boron (5 mg L−1) was determined with quantitative recovery in the presence of 100-fold concentration (except 5-fold for Fe3+) levels of the potentially interferent ions (Cl−, SO42−, HCO3−, CO32−, NO32−, PO43−, NH4+, Cu2+, Mg2+, Ca2+, Na+, K+, Fe3+) in water using the proposed SWV method. Fe3+ and Cu2+ interferences could be overcome with cation exchange resin removal. Additionally, boron was determined in synthetic and real seawater samples. The proposed SWV method was statistically validated against the spectrophotometric carmine method using seawater, antibacterial hand sanitizer gel and boron/potassium nitrate (BPN) pyrotechnic formulation.

Determination of methylisothiazolinone in waters. Comprehensive study about electrochemical behaviour on gold electrode and optimization of square-wave voltammetric methods

Abstract Methylsiothiazolinone (MIT) is a wide spectrum biocide used in different industrial fields. In this paper, the electrochemical behaviour of MIT on gold electrode has been studied and square wave voltammetric methods have been developed to determine this compound at different concentration levels. MIT exhibited and irreversible and diffusion- controlled oxidation process with potential and peak current values pH dependent. This biocide can be determined by square-wave voltammetry (SWV) with a linear response up to 53 mg L−1. Using an adsorptive stripping approach prior to the square-wave voltammetry (SWAdSV) it is possible to analyse samples containing very low concentrations of MIT, with a limit of detection of 0.0080 mg L−1. Both SWV and SWAdSV methods were applied with successful results to determine MIT in different water samples.

Determination of Ivabradine by Linear Sweep, Square Wave and Differential Pulse Voltammetric Methods Using Platinum Electrode in Pharmaceutical Preparation

Objectives: In this study, simple, fast and reliable cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) methods were developed and validated for determination of ivabradine in pharmaceutical preparations. Methods: The proposed methods were based on electrochemical oxidation of ivabradine at platinum electrode in acetonitrile solution containing 0.1 M LiCIO4.The well-defined oxidation peak was observed at 1.34 V. Results: The calibration curves were linear for ivabradine at the concentration range of 5-40 µg/mL for LSV, SWV and DPV methods, respectively. Intra- and inter-day precision values for ivabradine were less than 3.12, and accuracy (relative error) was better than 4.78%. The limits of detection values ranged from 1.20 to 1.60 µg/mL and quantification from 3.60 to 4.80 µg/mL. The mean recovery of ivabradine was 99.9% for pharmaceutical preparation. No interference was found from tablet excipients at the selected assay conditions. Conclusion: Developed methods in this study are accurate, precise and can be easily applied to Coralan tablet as pharmaceutical preparation.