Wave Cathodic Stripping Voltammetry Research Articles

An Electrochemical Strategy for Detection of Trace‐Level Binapacryl Using Square‐Wave Cathodic Stripping Voltammetry

AbstractBinapacryl is a fungicide and miticide from the dinitrophenol group and is used to control fungi and mites in agricultural areas. Since even trace amounts of pesticides can be highly toxic to humans and the environment, accurate and sensitive analytical methods are needed for their determination. Therefore, the electrochemical behavior of binapacryl fungicide on the glassy carbon electrode (GCE) was investigated using square wave cathodic stripping voltammetry (SWCSV) and cyclic voltammetry (CV). Some parameters such as accumulation potential, accumulation time, pulse amplitude, frequency, and step potential were optimized on GCE. From the plotted calibration graph, the linear operating range was found to be 0.16–6.20 μM (0.06–2.0 mg/L), and accordingly the limit of detection (LOD) and limit of quantification (LOQ) for the first and second peak were 0.060 μM/0.201 μM and 0.0627 μM/0.209 μM, respectively. The proposed method was applied for spiked tap water, apple juice and grape juice samples. An electroreduction mechanism has also been proposed for binapacryl with the participation of 2e−/2H+ via the nitro group of the molecule. Also, the selectivity of the method was demonstrated by investigating the interference effects of some pesticides on the determination of binapacryl.

On-field high-resolution quantification of the cobalt fraction available for bio-uptake in natural waters using antifouling gel-integrated microelectrode arrays

We report the optimization, characterization, and validation of Adsorptive Square Wave Cathodic Stripping Voltammetry on antifouling gel-integrated microelectrode arrays for autonomous, direct monitoring of cobalt(II) metal species. Detection is accomplished by complexation with an added nioxime ligand. The limit of detection established for a 90 s accumulation time was 0.29 ± 0.01 nM in freshwater and 0.27 ± 0.06 nM in seawater. The microelectrode array was integrated in a submersible probe to automatically dose the complexing agent nioxime and realize an integrated sensing system. For the first time ever, the potentially bioavailable Co(II) fraction was determined in La Leyre River-Arcachon Bay continuum, enabling to evaluate the potential ecotoxicological impact of freshwater-carried Co(II) in the Arcachon Bay. The measured potentially bioavailable Co(II) concentrations were hazardous for aquatic biota along the continuum. The electrochemical Co(II) data were compared to ICP-MS data in various fractions to determine spatial Co(II) speciation.

Electro-kinetic investigations and voltammetric detection of anti-ulcer drug cinitapride at low-cost pencil graphite electrode

Herein, we proposed a cost-effective, eco-friendly, fast and sensitive square wave cathodic stripping voltammetry (SWCSV) and differential pulse cathodic stripping voltammetry (DPCSV) methods for the quantification of anti-ulcer drug cinitapride in pharmaceuticals. Cinitapride electrochemically reduced at pencil graphite electrode and gave an irreversible well-defined cathodic peak in cyclic, square wave, and differential pulse voltammograms. The effect of pH of buffer, scan rates, and drug concentration on peak current and peak potential were studied. The reduction of cinitapride at pencil graphite electrode was diffusion controlled and occurred via participation of two electrons and two protons (2e−/2H+). The various electro-kinetic parameters such as diffusion coefficient(Do), surface coverage (T o)and electron transfer coefficient (α) were calculated, additionally, the mechanism of reduction of cinitapride at pencil graphite electrode was also proposed. The peak currents vary linearly in the concentration range 2.48 μmolL−1 to 17.39 μmolL−1 for all the voltammetric techniques. The obtained value of LOD for SWCSV and DPCSV techniques were2.48 μmolL−1 and 3.19 μmolL−1, respectively, which proved higher sensitivity of the proposed methods.

Novel magneto-electrochemical determination of Mn(II)

This study describes the robust modification of a screen-printed carbon electrode (SPE) for the magneto-electrochemical determination of Mn2+, in real soil samples, by square wave cathodic stripping voltammetry (SW-CSV). The carbon surface of a SPE was modified with electrodeposited Au, then dropcast with Fe3O4 NPs functionalised with l-cysteine within a graphene oxide matrix. The magnetic Fe3O4 NPs within the modification significantly increased the diffusion coefficient of the paramagnetic Mn2+ ion during deposition. Likewise, it also increased the number of hydroxyls available for the formation of the MnO2 layer, attributed to chiral induced spin selectivity. The reduced graphene oxide (RGO) served to increase the surface area and heterogenous electron transfer rate of the intermediate reactions. The Au/l-cys/Fe3O4/RGO modification displayed two significant improvements: enhancement of the Mn2+ response signal (212-fold increase) and improved flexibility for the analytical method (linear ranges from 0.5 to 300 µg L-1 to 62 – 1500 µg L-1 using deposition times of 300 or 30 s, respectively). Ten soil sample extracts were tested for Mn2+, by SW-CSV using the Au/l-cys/Fe3O4/RGO modified SPE, and showed good agreement with FAAS, average error of 6.8%.

Electrochemical Monitoring of Manganese in Drinking Water

Low levels of Mn are essential for many metabolic processes in the human body, yet excessive exposure to this heavy metal has been correlated to neurodegenerative diseases with Parkinson’s like symptoms in adults and neurological deficits in children. Erosion of Mn rich soil and rocks and human activities directly pollute groundwater which supplies drinking water for 51% of the total US population and 99% of the rural population. Hence contaminated drinking water represents one of the major sources of Mn intake. The non-enforceable updated guideline set by the EPA is 50ppb Mn. Trace metal analytical methods such as ICP-MS and AAS are limited to centralized laboratory testing and not feasible for point-of-care. Our work is aimed at the development of an electrochemical platform for efficient and rapid Mn detection in drinking water. The core technique is Square Wave Cathodic Stripping Voltammetry (SWCSV), carried out on disposable three-electrode sensors with a platinum working electrode, platinum counter electrode and an electroplated Ag/AgCl reference electrode. A 3D printed interface integrates a small vibration motor for effective agitation of the 12µL droplet sample during the deposition phase and allows connection to a commercial potentiostat. Figure 1(a) depicts the hardware components of the platform, with an onset on the sensor configuration. First, the system performances are characterized in standard solutions. Compared to peak amplitude, peak area is found to be a more suitable indicator of Mn concentration, with a linearity of R^2=0.998 in the range 5ppb-200ppb. The introduction of an embedded agitation mechanism allows for a reduction in the limit of quantitation (LOQ) from 5ppb to 3ppb and an approximate 2.3X increase in sensitivity from 9.09nC/ppb to 20.75nC/ppb. Analysis of tap water is then performed to confirm the capabilities of the electrochemical platform in more complex matrices. With optimal SWCSV parameters a limit of quantitation of 6ppb, a sensitivity of 26.45 nC/ppb and a linearity with R^2=0.995 are achieved. The developed protocol requires minimal sample preparation of the water samples, with a 2X dilution in 0.2M Acetate Buffer to provide enough ionic strength to sustain the faradaic reactions and buffer the pH at 4.7. 3-point standard addition is executed to determine the Mn concentration in unknown specimens and performances are compared to ICP-MS on the analysis of 78 tap water and well water samples from Holliston, MA with concentrations in the range 0.03ppb-5.3ppm. 100% agreement, 70% accuracy and 91% precision were obtained. Figure 1(b) shows typical voltammograms from the measurement of the unknown sample and the 3 spikes at known Mn concentrations to implement the 3-point standard addition. To enhance monitoring of water quality in local communities and rural areas, parallelization of the measurements can further reduce the analytical time and improvements in the interface can ultimately make the devised portable and easy-to-use electrochemical station soon deployable for practical on-the-field testing. Figure 1

Determination of Manganese in Human Whole Blood with Indium Tin Oxide Electrochemical Point-of-Care Sensor

Manganese (Mn) is one of the most common elements in the earth’s crust, and its compounds are widely used in consumer products including gasoline, cell phone batteries, fertilizer, pigments, fireworks, etc. Although a trace metal in the human body and under tight homeostatic control, elevated levels of Mn due to occupational or environmental exposure can cause serious adverse health effects, such as manganism (a Parkinsonian-like syndrome), liver cirrhosis, and Behcet disease. The normal range of Mn in blood is 4.7-18.3 µg/L (5-20 ppb), and values greater than 36 µg/L correlate with disease. The current method for analyzing Mn in blood is via inductively coupled plasma mass spectrometry (ICP-MS) in centralized labs, which requires a venipuncture sample, can take 3-6 months for analyses, and can be costly. Electrochemical analysis can offer an attractive alternative, leading to developing a point-of-care system for Mn monitoring in blood, with the advantages of being inexpensive and easily miniaturized. Herein, we report the first Indium Tin Oxide (ITO) electrochemical microsensor capable of accurately measuring Mn levels in human blood with cathodic stripping voltammetry (CSV). As shown in Fig. 1 (a), the ITO microsensor was developed by integrating a screen-printed carbon auxiliary electrode and an Ag/AgCl reference electrode on an ITO coated glass slide (1 cm × 4 cm). A circular ITO film with 3 mm diameter was exposed and used as the working electrode. To start electrochemical analysis, blood sample was first microwave digested with nitric acid and hydrogen peroxide to release Mn2+ bound to the proteins. The acid-digested blood sample was then titrated with sodium hydroxide to pH 5. Square wave cathodic stripping voltammetry (SWCSV) with optimized parameters was carried out to construct the calibration curve in the digested & pH adjusted blood sample with the Mn concentration ranging from 1.2 ppb to 25 ppb (confirmed by ICP-MS). The voltammogram in Fig. 1(b) shows an increasing trend of peak height and area with Mn concentration; and the calibration curve in Fig. 1(c) shows a sensitivity of 38.6 nC/ppb and linearity of 0.997 from the sensor’s measurements. We used the same stripping parameters, while applying a 3-point standard addition method, to determine the Mn concentration in two blood samples. The concentrations of 10.5 ppb and 26.3 ppb from our measurements lead to an average accuracy of 90% in comparison to the ICP-MS results of 8.9 ppb and 27.6 ppb. Four 150 µl sample droplets with a total volume of 600 µl were used in the measurement. Considering the 10X dilution from the blood digestion and pH adjustment process, only 60 µl of whole blood is needed to determine the Mn level with our approach. The favorable results and the small blood volume required in this work suggests the feasibility of point-of-care monitoring Mn in blood and is expected to be very useful for monitoring Mn exposure in vulnerable populations like children. Figure 1

Phaeophyceae and rhodophyceae macroalgae from the Antarctic: A source of selenium

This study reports the development of a voltammetric method applied for Se determination in Phaeophyceae (A. utricularis, C. jacquinotii, A. mirabilis, D. anceps, H. grandifolius) and Rhodophyceae (G. confluens, C. racovitzae, I. cordata) macroalgae from the Antarctic. Evaluation of the instrumental parameters showed the square wave cathodic stripping voltammetry provided greater sensitivity (deposition potential, -0.4 V; deposition time, 420 s; amplitude, 0.08 V; frequency, 60 Hz) than influence of differential pulse cathodic stripping voltammetry. The matrix effect and the influence of Cu concentration on the determinations were also assessed. After microwave-assisted digestion of the samples, the quantification limit was from 5.21 × 10−3 (G.confluens) to 9.85 × 10−3 mg kg-1 (I. cordata). The quantification of Se was carried out over the concentration range from 0.23 (C. jacquinotii) to 1.22 mg kg-1 (A. mirabilis). The method accuracy was by analysing the reference material of peach leaves (SRM 1547).

Chemically modified electrode based on dihexadecyl hydrogen phosphate and carbonaceous materials: improvement of analytical and electrochemical features applied to uranium determination

This work deals about the evaluation and improvement of analytical and electrochemical features of chemically modified electrode based on dihexadecyl hydrogen phosphate (DPH) and carbonaceous materials. The electrochemical features of films obtained were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Between the modifications evaluated, the glassy carbon electrode (GCE) modified with CB and DPH (DHP-CB/GCE) showed lower resistance to charge transfer and higher electron transfer rate. Additionally, the highest current of U(VI) was obtained with DHP-CB/GCE in a very stable way, the process present quasi-reversible behavior and it is controlled by a mixture of diffusion and absorption. The best instrumental conditions for U(VI) determination were obtained applying frequency of 15 Hz, amplitude of 100 mV, and deposition potential of − 0.1 V (by square wave cathodic stripping voltammetry). Among the electrolyte compositions (acetate and citrate buffers), ionic strength (from 0.10, 0.15, to 0.20 mol L−1), and pH (from 3.6 to 5.6) evaluated, the highest current of U(VI) were obtained in 0.15 mol L−1 of acetate buffer, pH 5.6. The method was accurate, linear, and sensitive (detection limit of 0.088 μg L−1 using 300 s of deposition).

Chemometric Optimization of the Methodology for Determination of Molybdenum in Soils and Plants by Square Wave Adsorptive Stripping Voltammetry

The method is based on the adsorptive accumulation of complex molybdenum(VI) with 8-hydroxyquinoline, using voltammetric square wave cathodic stripping voltammetry. The composition and concentration of the supporting electrolyte, frequency (Hz), amplitude (mV) and deposition time (s), were optimized by factorial design in relation to current reduction of molybdenum(VI). The optimum methodology provided the following values for the process variables: scan increase (0.5 mV), pulse amplitude (127 mV), frequency (96 Hz), adsorption time (80 s) and drop size (0.60 mm2), the concentration of KNO3 (2.0 mol L-1), acetate buffer (0.5 mol L-1) and 8-hydroxyquinoline (0.01 mol L-1). The results obtained after optimization showed a linear response in the range from 1.0 to 6.0 mg L-1 and limits of detection and quantification, respectively equal to 0.02 and 0.08 mg L-1. The molybdenum contained in the samples were determined using the optimized methodology, with values consistent with the values determined by atomic emission spectrometry with inductively coupled plasma (ICP-AES).

Ultrasonic-Assisted Digestion of Cement and Clinker Samples for the Determination of Manganese by Square Wave Cathodic Stripping Voltammetry

Cement and clinker are complex samples and constitute a challenge for elemental analysis. Manganese, usually present in these matrices, can accumulate in bones, liver, the pancreas, kidneys, and brain and its monitoring is very important. This work presents an alternative method of sample treatment based on ultrasonic-assisted extraction for the determination of trace amounts of manganese in cement and clinker samples by square wave cathodic stripping voltammetry (SWCSV) on a gold working electrodes. The proposed extraction procedure occurs at room temperature inside closed vessels and uses 3.0 mol L−1 HCl solution, a less corrosive extractant compared to concentrated acids. Ultrasonic extraction was compared with conventional extraction by heating on hot plate and no significant differences between the two extraction methods were observed at the 95% confidence level. The possible use of H2O2 in the extraction process was evaluated but not used due to its interferences in the electrochemical determination of manganese. The SWCSV results obtained employing 0.20 mol L−1 H3BO3/0.10 mol L−1 KCl electrolyte at pH 6.5 produced two distinct linear regions of concentration for the analytical curve from 1.1 to 2.0 × 10−7 mol L−1 and from 2.0 to 3.2 × 10−7 mol L−1. The limits of detection and quantification were 3.1 × 10−8 mol L−1 and 9.8 × 10−8 mol L−1, respectively, and suitable for the proposed application. The results obtained by SWCSV were consistent with those obtained by flame atomic absorption spectrometry (FAAS) at the 95% confidence level.

Bis[2-(methacryloyloxy)ethyl] phosphate radiografted into track-etched PVDF for uranium (VI) determination by means of cathodic stripping voltammetry

We report the radiation grafting of bis[2-(methacryloyloxy)ethyl] phosphate (B2MP) through electron-beam onto PVDF films and through swift heavy ions (SHI) irradiations into the pores of track-etched PVDF membranes. Radiolytically produced radicals were studied using EPR. To adapt the radiation grafting protocol inside the nanopores of track-etched membranes, the electron-beam irradiated films at varying monomer concentrations, doses and solvent mixtures were first studied. It was found that track-etched membranes, even after 1 h of chemical treatment, do not require a post-etching irradiation to initiate free-radical polymerization of B2MP from remaining radiationinduced radicals. The presence of functional groups inside the nanopores of the membrane were examined using FTIR and XPS. After exposure of B2MP-g-PVDF membranes to a uranyl solution, XPS was also exploited to evidence of O2UO22+ trapping inside the membrane nanoporosity by tracking the presence of U 4f peak. The B2MP-g-PVDF membranes were converted into electrodes by depositing 35 nm of gold on each side through a mask. Detection of ppb concentrations (from 20 to 100 ppb) of uranyl by B2MP-g-PVDF membrane electrodes was demonstrated by means of square wave cathodic stripping voltammetry (SW-CSV). The limit of detection (LOD) was estimated to be 17 ppb (3σ−/ slope).

Cathodic Stripping Voltammetric Study for Determination of Inorganic Arsenic Species in Seaweed Gracilaria fisheri

A simple, rapid, selective and sensitive square wave cathodic stripping voltammetry (SWCSV) at a hanging mercury drop electrode (HMDE) for the determination of As(III), As(V) and inorganic As(total) in seaweed was developed. The method was based on the formation of copper-arsenic intermetallic compound in the presence of HCl onto a HMDE at a constant potential of -0.40 V vs. Ag/AgCl in the deposition step, followed by the reduction of deposited compound to arsine at a potential of -0.78 V in the stripping step. In the system, only As(III) was directly measured, whereas inorganic As(total) was measured by reducing As(V) to As(III) using thiosulfate. In the deposition step, the use of 10 mg L-1 Cu(II) and 1 M HCl was recommended for the determination of 2 µg L-1 As(III) under the optimum instrumental variables obtained at 150 s for deposition time and 2000 rpm for stirring speed with the highest deposition efficiency of 16.15 and 88.49%, respectively. In the determination of As(V), two values of the highest reduction efficiency obtained using concentration of 40 mg L-1 thiosulfate, and reducing time at 300 s were 98.15% and 37.89%, respectively. In the measurement, the quantification limits of As(III) and As(V) were 0.46, and 1.62 µg L-1, respectively. The relative standard deviation (n=10) for 2 ug L-1 As(III) and As(V) were 5.20% and 2.57%, respectively. The proposed method was applied to the determination of inorganic arsenic species in seaweed Gracilaria fisheri.

Raman, X‐Ray Fluorescence Spectroscopies and Graphene Oxide Modified Screen Printed Electrodes to Identify the Pigments and Earth Present in Ancient Leather Samples

AbstractMicro‐Raman and X‐Ray Fluorescence combined with electrochemical techniques proved to be suitable for the unambiguous identification of the green pigment in a very deteriorated historical leather. The colouring matter resulted in a mixture of blue and yellow. Raman identified the blue indigo, whereas iron and arsenic were identified by XRF. The redox status of these two elements was investigated by Square Wave Cathodic Stripping Voltammetry (SWCSV). Results demonstrated the presence of As(III), probably As2S3 (orpiment), and Fe(III), characterising the red earths. The quantitative results obtained by SWCSV were also confirmed for Fe and As by ICP‐MS (Inductively Coupled Plasma Mass spectrometry). Voltammetric techniques, applied here for the identification of the redox status of the elements, contained in pigments, are useful to understand two important aspects: the chemical‐physical composition of the colors and the best strategy to be applied for the preservation of the pigments in ancient/deteriorated artwork objects.

Sensitive Electrochemical Determination of Folic Acid Using ex–situ Prepared Bismuth Film Electrodes

The electrochemical behavior of folic acid (FA), at the electrochemically prepared ex situ bismuth film (BiF) on glassy carbon electrode, clearly indicates electrocatalytic nature of the prepared film toward FA reduction (at –0.55 V). Scanning electron microscopy is used for morphological characterization of the prepared BiF. Accordingly, we establishing an electrochemical procedure based on square wave cathodic stripping voltammetry, preceded by accumulation of FA on the BiF electrode (BiFE). This analytical method is optimized and its analytical performance is presented. This electrode displays a two linear response range: 0.1 to 1.0 μmol L–1 and 1.0 – 10.0 μmol L–1 with sensitivity of 20.10 μA μmol–1 L and 2.28 μA μmol–1 L, respectively. Developed method was validated in compliance with spectrophotometric method. Excellent recovery and standard deviation obtained with BiFE revealed great analytical potential of the proposed method which was applied for the determination of FA in pharmaceuticals formulation.

Voltammetric analysis of disulfiram in pharmaceuticals with a cyclic renewable silver amalgam film electrode

Electrochemical properties of disulfiram, representative of highly significant bioactive compounds, were studied with a cyclic renewable silver amalgam film electrode (Hg(Ag)FE) using square wave cathodic stripping voltammetry (SWCSV). The influence of various factors such as pH, buffer concentration, buffer composition, and SWCSV parameters on current response was investigated. The optimum results in terms of signal shape and intensity were recorded in Britton--Robinson buffer (pH 7.5) at -0.5 V versus Ag/AgCl/3 mol L$^{-1}$ KCl. An elaborated electroanalytical procedure was used to determine disulfiram at the Hg(Ag)FE in the concentration range from 0.05 to 5.00 $\mu $M. Precision, repeatability, and accuracy of the method as well as the influence of possible interferences were ascertained. The detection and quantification limits were 11 nM and 37 nM, respectively. The applicability of the developed method was tested in the determination of disulfiram in the commercial formulation Anticol. Thin-layer chromatography with image processing software was used to validate the accuracy of the method.

“In-situ” antimony film electrode for the determination of tetracyclines in Argentinean honey samples

The main goal of this work is the application of an antimony film electrode (SbFE) prepared for the first time “in-situ” to determine organic compound as tetracyclines commonly used in Argentine for hive treatment. The SbFE was prepared on a glassy carbon electrode (GCE) and square wave cathodic stripping voltammetry (SWCSV) technique was used. The SWCSV parameters were optimized based on a Draper Lin small composite design. The SWCSV response was linear in the TCs concentration range from 0.40 to 3.00μM with a limit of detection (LOD) of 0.15μM. The proposed method is a good and simple alternative to the determination of tetracyclines in Argentinean honeys samples. Recovery experiments were performed using spiked honey samples with standard deviation values from 0.75% and 9.69%.

Adsorptive stripping voltammetric determination of anticancer drug lomustine in biological fluids using in situ mercury film coated graphite pencil electrode

Abstract In situ mercury film coated graphite pencil electrode (MF/GPE) was prepared and applied for selective and sensitive electrochemical determination of anticancer drug lomustine (LMT). Parameter optimization for the preparation of MF/GPE was examined. The bare and modified GPEs were characterized by scanning electron microscopy (SEM), cyclic voltammetry and square wave voltammetry. With pH 5.0, Britton–Robinson (BR) buffer and in the presence of 0.5 M sulfate ions as indifferent supporting electrolyte, LMT yields a well defined and sensitive reduction peak at the MF/GPE. The electrochemical parameters such as the charge value (Q), surface concentration (Γ), electron transfer coefficient (α) and the standard rate constant (ks) for the reduction of LMT at the MF/GPE were calculated. The achieved limits of detection and quantification were 8.13 × 10− 8 M and 2.71 × 10− 7 M by square wave cathodic adsorptive stripping voltammetry (SWCASV), respectively. The modified MF/GPE was used as a sensor for the detection of LMT in human blood and urine samples with good accuracy and precision.

Electrochemical behavior and assay of anti-Parkinson drug selegiline using cathodic adsorptive stripping square wave voltammetry in bulk form

Electrochemical behavior and assay of anti-Parkinson drug selegiline using cathodic adsorptive stripping square wave voltammetry in bulk form Priyanka Sinha, Anjuman Shekhawat, Digish K Sharma Electrochemical Research Laboratory, Department of Chemistry, University of Rajasthan, Jaipur, India Abstract: The electrochemical reduction behavior of selegiline was investigated by cyclic voltammetry using glassy carbon electrode and validated by square wave cathodic adsorptive stripping voltammetry. Selegiline gave one well-defined reduction peak in the potential range −0.4 to −0.5 V versus Ag/AgCl electrode. The reduction process is irreversible and partial diffusion controlled. Various chemical and instrumental parameters affecting the electroanalytical response for the determination of selegiline were investigated and optimized. Under optimized conditions, the adsorptive stripping peak current is found to be linear over the concentration range of 3.0×10–7–2.5×10–5 M with a detection limit of 3.04×10–8 M and a lower limit of quantification of 1.01×10–7 M. Keywords: selegiline, anti-Parkinson drug, glassy carbon electrode, square wave cathodic adsorptive stripping voltammetry, diffusion controlled

Square Wave Cathodic Adsorptive Stripping Voltammetric Determination of the Anticancer Drugs Flutamide and Irinotecan in Biological Fluids Using Renewable Pencil Graphite Electrodes

AbstractA sensitive electrochemical method based on square wave cathodic adsorptive stripping voltammetry (SWCASV) using pencil graphite electrodes (PGE) was developed for the individual and simultaneous determination of the anticancer drugs flutamide (Flu) and irinotecan (Irino) in biological fluids. Calibration curves showed an excellent linear response with limits of detection of 1.68×10−9 and 1.55×10−8 M Irino and Flu, respectively. The statistical evaluation of within‐day repeatability (n=5) and day to day precision (n=5) showed satisfactory accuracy and precision. SWCASV using a PGE for individual and simultaneous determination of both drugs in bulk form, human urine and serum samples was demonstrated.

Determination of metallothionein in Daphnia magna by modified square wave cathodic stripping voltammetry

Metallothioneins (MTs) are widely used as biomarkers in environmental studies. However, eliminating interfering factors for MT determination in vivo by electrochemical detection is difficult. In this study, NO3− and Cl− were found to negatively affect MT determination in Daphnia magna by square wave cathodic stripping voltammetry (SWCSV). The relevant mechanism was analyzed, and results were used to modify the original electrochemical testing parameters and environmental conditions. This modified SWCSV achieved accurate MT concentrations in D. magna, leading to detection limits as low as picomolar levels.