Stripping Voltammetry Method Research Articles

Organic Copper Speciation by Anodic Stripping Voltammetry in Estuarine Waters With High Dissolved Organic Matter.

The determination of copper (Cu) speciation and its bioavailability in natural waters is an important issue due to its specific role as an essential micronutrient but also a toxic element at elevated concentrations. Here, we report an improved anodic stripping voltammetry (ASV) method for organic Cu speciation, intended to eliminate the important problem of surface-active substances (SAS) interference on the voltammetric signal, hindering measurements in samples with high organic matter concentration. The method relies on the addition of nonionic surfactant Triton-X-100 (T-X-100) at a concentration of 1 mg L−1. T-X-100 competitively inhibits the adsorption of SAS on the Hg electrode, consequently 1) diminishing SAS influence during the deposition step and 2) strongly improving the shape of the stripping Cu peak by eliminating the high background current due to the adsorbed SAS, making the extraction of Cu peak intensities much more convenient. Performed tests revealed that the addition of T-X-100, in the concentration used here, does not have any influence on the determination of Cu complexation parameters and thus is considered "interference-free." The method was tested using fulvic acid as a model of natural organic matter and applied for the determination of Cu speciation in samples collected in the Arno River estuary (Italy) (in spring and summer), characterized by a high dissolved organic carbon (DOC) concentration (up to 5.2 mgC L−1) and anthropogenic Cu input during the tourist season (up to 48 nM of total dissolved Cu). In all the samples, two classes of ligands (denoted as L1 and L2) were determined in concentrations ranging from 3.5 ± 2.9 to 63 ± 4 nM eq Cu for L1 and 17 ± 4 to 104 ± 7 nM eq Cu for L2, with stability constants logK Cu,1 = 9.6 ± 0.2–10.8 ± 0.6 and logK Cu,2 = 8.2 ± 0.3–9.0 ± 0.3. Different linear relationships between DOC and total ligand concentrations between the two seasons suggest a higher abundance of organic ligands in the DOM pool in spring, which is linked to a higher input of terrestrial humic substances into the estuary. This implies that terrestrial humic substances represent a significant pool of Cu-binding ligands in the Arno River estuary.

Wide-range detection of Cu-binding organic ligands in seawater using reverse titration

The toxicity and bioavailability of Cu in seawater were estimated using its chemical speciation. In this study, the concentrations and conditional stability constants (K'CuL) of Cu complexes with Cu-binding organic ligands (L) in seawater were determined using the reverse titration–competitive ligand exchange–adsorptive cathodic stripping voltammetry method. The concentrations of strong and weak ligands (L1 and L2, respectively) were determined using reverse titration via the addition of Cu to seawater samples to achieve ligand saturation. Our results revealed that the reverse titration method can be successfully used for the detection of high concentrations of L2. Using the reverse titration method, we detected L2 concentrations that exceeded 80 and 120 nM in seawater samples from the subtropical western North Pacific Ocean and Otsuchi Bay Japan, respectively. The K′CuL1 and K′CuL2 values obtained using the reverse titration method were comparable with those obtained using the forward titration method. Therefore, the reverse titration method can be used to determine the chemical speciation of Cu in the ocean and coastal regions as supplement to the more conventional forward titration method.

Anodic stripping voltammetry analysis of gold nanoparticles functionalized one-dimensional single polypyrrole nanowire for arsenic sensing

Emerging sensor technology has led to develop high-performance sensors that satisfy most of the sensing parameters. However, still further advances are needed for sensors to achieve low detection, which is crucial for the detection of low concentration analytes present in the solution. Herein, we designed a sensor electrode with gold nanoparticles (AuNPs) functionalized single polypyrrole nanowire (PpyNW) to detect arsenic (III) in water samples. The chronocoulometry and cyclic voltammetry methods were used to synthesize PpyNW and AuNPs, respectively. The morphological and elemental analysis of PpyNW functionalized with AuNPs was done using field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS), respectively. After fixing PpyNW on the electrode, the surface was functionalized with AuNPs. The sensing performance of the AuNPs/PpyNW sensor was monitored using anodic stripping voltammetry method. From the obtained data, the sensor showed high sensitivity of 63.13 mA/mM (i.e. 0.8417 mA/ppb) and an ultra-low detection limit of 0.005 mM (i.e. 0.37 ppb) during arsenic (III) detection in solution. Furthermore, we tested the sensing performance of our sensor in the laboratory-grade and adulterated tap water samples to determine arsenic (III) concentrations.

Изучение влияния мешающих ионов тяжелых металлов и различной пробоподготовки на определение примеси ртути в протамина сульфате методом инверсионной вольтамперометрии

Aim. To determine the content of mercury in protamine sulfate samples with different sample preparation. To study the effect of interfering ions on the content of mercury impurity in protamine sulfate by stripping voltammetry (SV). Materials and methods. We used a solution for injection of protamine sulfate, batches 515091, 514062, 514111; for sample preparation — various options for dilution and precipitation. Dilution was carried out with bidistilled water, and the precipitation of proteins — with sodium tungstate in 2 options. Mercury impurities were determined by the SV method. Results. The mercury content in protamine sulfate samples was 0.000417 ± 0.00140 and 0.000420 ± 0.00152 mg/l when diluted with water 1 : 2 and 1 : 1 respectively and 0.000462 ± 0.00131 and 0.000459 ± 0.00121 when precipitated with tungstate in options 1 and 2 respectively. With the addition of an interfering ion, for example, Cu2+, the content of mercury in the medicinal product was 0.000606 ± 0.00015, 0.000452 ± 0.00013 and 0.0004212 ± 0.00011 mg/l for protamine sulfate batches 514062, 515091 and 514111 respectively, which does not exceed the values determined by the product specification. The addition of Pb2+, Fe2+, Zn2+, Cu2+, and Cd2+ ions also had no effect on the determination of the mercury content in protamine sulfate samples. Conclusion. To determine the mercury impurity in the protamine sulfate, special sample preparation is not required. Ions of Cu2+, Pb2+, Fe2+, Cd2+, Zn2+ do not affect the result of determining the mercury content in protamine sulfate samples by the SV method, which indicates a high selectivity of the method used.

Сравнение методик количественного определения фармацевтической субстанции висмута субсалицилата методами УФ-спектрофотометрии и инверсионной вольтамперометрии

The results of a comparative study of methods for the quantitative determination of the active pharmaceutical substance (APS) bismuth subsalicylate by UV-spectrophotometry and stripping voltammetry (SV) are presented. Partial validation of the compared methods was carried out according to the following characteristics: linearity, detection limit, limit of quantification, accuracy. In the course of linearity assessment, the values of the correlation coefficient of the methods were established — 0.9987 for UV-spectrophotometry and 0.9982 for SV. The detection limit and the limit of quantification for UV-spectrophotometry were 2.35 and 7.12 μg/ml respectively, for SV — 1.16 and 3.52 μg respectively. The accuracy was determined by the constant term of the linearity equation, which was 3.34% of the interval’s middle value when analyzed by UV-spectrophotometry and 1.93% by SV. Thus, both methods can be used for the quantitative determination of the APS of bismuth subsalicylate; however, due to the fact that the content of bismuth is mainly determined in this case, the SV method is more preferable since it allows analyzing this particular part of the molecule.

Analysis of Tear Fluid for Evaluation on the Concentration of the Generic Anti-Glaucoma Drug Betoptik using Multisensory Stripping Voltammetry and Multivariate Statistics

It is important to monitor the concentration of drugs after their instillation: this helps to find the right drug dosages. The proposed method is based on recognizing multidimensional images through the use of multidimensional statistics; the images are produced by multisensory electrochemical systems that provide reliable information about the tested objects. The measurements were carried out using a planar solid-state electrode. The test-system solution was a 0.05 М KCl solution, which contained the Zn2+, Cd2+, Рb2+, Cu2+ Со2+, and Hg2+ metal cations at the concentration of 5 10–5 M. A new electrochemical method for multisensory stripping voltammetry has been used to determine whether it is appropriate for determination of generic forms of the drug Betoptic, that is, Xonef, Betoftan, and Betalink EU in tear fluid. Measurements were carried out on a planar three-electrode interdigitated electrode. It has been shown that this method is effective for determination of the generics. The dynamics of changes in their concentrations over time were examined. After instillation of the generics in glaucoma patients, their concentrations in the Tear fluid remained unchanged within 12 h. The list of organic substances that can be determined by the method of multisensory stripping voltammetry has been extended.

Voltammetric Study for Determination of Non-essential Metal Cd(II) in water samples (River and Sea) using Eriochrome Blue Black R as Complexing

The research on the determination of Cd(II) metal in river and seawater samples using the Adsortive Cathodic Stripping Voltammetry (AdCSV) method has been done. In order to increase the sensitivity and selectivity of Cd(II) measurement, it is necessary to determine the optimum condition for the variation of potential ligand accumulation, accumulation time, pH and optimum ligand concentration. It is also determined the accuracy and precision of the method used by determining the value of the relative standard deviation (SDR), as well as the recovery value. The result obtained is chalcone as the optimum ligand, the optimum accumulation potential is -0.1 V, the optimum accumulation time is 60 seconds, the optimum solution pH is 6, and the optimum chalcone concentration is 0.5 mM. The relative standard deviation value is 4.27%, the recovery value is 98.31%. The application of the VSAd method to water sample results the concentration of Cu(II) metal in the sample of Bangek river, Indonesia is 4.778 g/L and seawater in Teluk Kabung, Indonesia is 5.189 g/L.

MTech POL-20 – universal polarograph for electrochemical analytical methods

The simple version of multyfunctional universal polarograph MTech POL-20 based on microcontroller C8051F350 has been designed. The polarograph has functionalities of potentiostat and galvanostat. The C8051F350 chip is fully integrated, low power, mixed-signal system-on-a-chip microconroller unit. It includes high-speed 8051-compatible core, precision programmable 24.5 MHz internal oscillator, 8 kbytes of on-chip flash memory, 24-bit analog to digital converter with analog multiplexer, two 8-bit current output digital to analog converters and 2.5 V voltage reference. The polarograph controls the potential between the working electrode and the reference electrode in range ±2.5 V. The device has four ranges of measured current with programmed selecting: ±15, ±100, ±500 and ±2500 uA. The device can measure voltammograms under high sweep rate from 0.01 and up to 100 mV/s. The polarograph is equipped with RS232-USB converter based on PL2303 chip for power supply and communication with the computer through USB port. Computer program on Visual Basic 5.0 language for operating with potentiostat has been developed. This software allow to measure and visualize voltamperograms, chronopotentiograms and chronoamperograms. For reduction of influence of electromagnetic noise and improvement signal/noise ratio the program makes digital processing of measured polarograms by Savitzky-Golay filter. Potentiostat-galvanostat MTech POL-20 has been successfully tested on model systems using resistive electrochemical equivalents. Also, the polarograph was successfully tested on determination of Pb(II) by anodic stripping voltammetry method. The device is suitable for the main electrochemical measuring techniques and well-known analysis methods: potentiometry and potentiometric titration, coulometry and coulometric titration, voltammetry with different types of potential sweep – linear, normal pulse, differential pulse and square-wave. Keywords : polarograph, potentiostat, galvanostat, microcontroller C8051F350, voltammetry, potentiometry.

Effect of Boron Doping Level on BDD Electrode for Heavy Metal Ion Sensor

Recently, industrial wastewater is being discharged in large quantities due to the development of industry and this wastewater contains a various heavy metal ion. Exposure to high levels of trace metal ions [Cd (II), Pb (II), Cu (II)] causes a variety of health and environmental problems. These toxic species accumulated in the human body through the water source have a low rate of clearance. [1,2]To minimize the exposure of humans to these contaminants through effective water quality monitoring, anode stripping voltammetry (ASV) method was used. ASV method has wide linear dynamic range, low detection limit (ppb), multi-element analysis capability and the simplicity of the instrumentation, which is relatively inexpensive and small in size, requires low levels of electrical power and is sufficiently portable to permit its use in the field. So, ASV has been used successfully for the determination of heavy metals in water. The sensitivity of differential pulse anode stripping voltammetry (DPASV) is higher than other classical voltammetry, because of its enhanced faradaic current and decreased non-faradaic charging current. [2]In generally, Ir, Au, Ag and Hg electrodes have been used for stripping analysis of trace metals, but the Ir, Au, Ag electrodes have low sensitivity, Hg electrode have toxicity and volatility. [2] To solve this drawbacks, we fabricate a Boron-doped diamond (BDD) electrodes. BDD electrodes are candidate for use in the detection of a trace heavy metal ions, because these show good electrical conductivity, low background current, and non-toxicity.In this study, BDD electrodes on Si substrate deposited by hot filament chemical vapour deposition (HFCVD) and applied to DPASV measurement. Through the optimization of the deposition condition of BDD electrodes and measurement condition of DPASV, we increased the detection sensitivity of heavy metal ions. The BDD electrode with the optimum boron doping concentration by controlling the boron doping concentration from 100 to 10000 ppm in the deposition process optimization step has excellent durability and selectivity of heavy metal ions. As a result of electrochemical measurement, BDD electrode with 8000 ppm B was displayed high sensitive response and wide potential window range of -1.7 V to 1.6 V with the detection limit of 0.001 mg/L to 0.01 mg/L ±5 % about heavy metal ions [Cd (II), Pb (II), Cu (II)].[1] M.O. Park et al, Electroanalysis. 2017, 29, pp. 514 – 520[2] J. –H. Yoon et al, Bull. Korean Chem. Soc. 2010, Vol. 31, No. 1This study was supported by the Korea Environmental Industry & Technology Institute[grant number 20190027400012] and R&D Center for Green Patrol Technologies through R&D for Global Top Environmental Technologies [grant number 20180018400013] funded by the Ministry of Environment, Republic of Korea (MOE), Figure 1

A Sensitive Carbon Paste Electrode for Selective Detection of Lead Based on the Synergistic Effect of Bismuth and Chelating Agent

A new type of carbon paste electrode (CPE) has been prepared by mixing bismuth oxide, diphenyl thiocarbazone and graphite powder (Bi-Di-CPE). Trace amount of Pb2+ has been detected via the differential pulse stripping voltammetry (DPV) method with Bi-Di-CPE, which exhibits an extremely high sensitivity about lead. The peak current of Bi-Di-CPE has a linear relationship with the concentration of lead in the range of 5–80 μg l−1, and the limit of detection is as low as 0.15 μg l−1, which meets the detection requirements of heavy metals in tap water (Pb ≤ 10 μg l−1) or in river water (Pb ≤ 50 μg l−1). The diphenyl thiocarbazone acts as a chelating agent which can selectively enriching lead. The bismuth oxide can provide bismuth film and further enriches the lead as a bismuth electrode in the electrodeposition process. The synergistic effect of the chelating agent and bismuth film of the Bi-Di-CPE brings high sensitivity and selectivity to detect heavy metals. Different kinds of modified CPE sensors towards different heavy metals with low cost and high performance may be achieved conveniently by using bismuth particles and corresponding chelating agents.

Determination of Anesthetics Used in Adult Ophthalmology by the Multisensory Stripping Voltammetry Method in Tear Fluids

For effective dosage of ophthalmic drugs, it is necessary to assess the dynamics of changes in their concentration in the tear fluid over time. This paper provides examples of determination of the local analgesic drugs naropin, сhirocaine, and lidocaine used in ophthalmic operations by multisensory stripping voltammetry. The dynamics of these anesthetics in the tear fluid of patients during the operation for phacoemulsification of the lens, including in the presence of concomitant glaucoma, was studied.

Breast Cancer Disease and Arsenic: “Geological Behavior (GBR) as Key “

Geology may appear remote from human health. However, rocks are the fundamental building blocks of the Earth’s surface, full of important minerals and chemical elements. Rock weathering and alteration products not only form our soils to support our crops but provide essential elements to build biology. Some heavy metals are carcinogenic, and some only affect the body’s ability to produce red and white cells. In fact, any heavy metal affects any part of the body due to our geological behavior (GBR). For example, a heavy metal may not cause any side effects by contact with the skin, even when swallowed, and may not cause serious harm, but inhaling the vapor of that heavy, toxic metal can cause severe damage to the lungs. Some heavy and quasi metals are more toxic, and some forms of heavy metal compounds are even more dangerous than other forms. Toxic and hazardous heavy metals like arsenic, lead, mercury, zinc, chromium and iron are found in a variety of personal care products, e.g., lipstick, whitening toothpaste, eyeliner and nail color. We use the Anodic Stripping voltammetry (ASV) method for arsenic detection, utilizing the PDV6000 + analyzer (Manufactured B3 Electronics, Perth Australia) configured with a solid gold electrode for total as analyses. Sample Preparation: Spot urine samples were collected from most of the participants from 1 January 2018 to 30 March 2020 after face to face interviews. Women with missing information on adjustment variable(s) were included in the analysis in a separate category for adjustment. Results: Our studies were focus in describing the mean Urinary Arsenic levels (u As) residents of in the central zones of Shiraz, Fasa, Abadeh, Jahrom and Marvdasht to compare the effect of diet such as consuming canned or frozen foods, Consume rice daily, smoking habits and lifestyle on the incidence of Breast. Conclusion: Cancer with arsenic compounds has been reported in many parts of the world. The disease affects all organs of the body, and every year many victims of cancer suffer from severe symptoms and even death. Arsenic compounds are present in the human body and environment in an inorganic and organic form. Inorganic arsenic includes arsenite and arsenic, can also be presented in the environment in the form of methyl (monthly arsenic acid and dimethyl arsenic acid). Arsenic, especially inorganic arsenic, is well absorbed through the gastrointestinal tract rivers (80% -90%) and will be scattered throughout the body. It is often metabolized by methylation and excreted mainly in the urine. Methylation of inorganic arsenic compounds is said to undergo a detoxification process.

Studies of mechanism, kinetic model and determination of bupivacaine and its application pharmaceutical forms

Bupivacaine, a local anesthetic that is often preferred in many wide ophthalmology applications, was investigated from different aspects such as electrochemical behavior, kinetic model, mechanism illumination, and analytical applications by cyclic voltammetry (CV) and square wave stripping voltammetry (SWSV) methods on glassy carbon electrode (GCE). Bupivacaine exhibited a well-defined anodic signal at nearly 850 mV, an irreversible and adsorption-controlled electrode process. Furthermore, a sensitive and selective SWSV method with a linear working range of 0.3–12.5 mg/L was developed for bupivacaine determination. Limits of detection (LOQ) and that of determination (LOD) were analyzed as 85 and 282 μg/L, respectively. In addition, the most probable study mechanism was carried out for the first time by this study. The selectivity of some co-existences such as heavy metals, ketotifen, moxifloxacin, ciprofloxacin, cyclopentanate and tropicamide was studied in 1 mg/L bupivacaine determination. They did not have a serious effect on bupivacaine determination at 5% tolerance limits. Otherwise, bupivacaine was successfully analyzed in matrix samples without any pretreatment by the proposed SWSV. Consequently, a fast, reliable, inexpensive, portable, eco-friendly, and sensitive new method has been developed to analyze bupivacaine in real samples.

Highly sensitive and selective sensor based on molecularly imprinted polymer for voltammetric determination of Nevirapine in biological samples

Abstract In the present study, a sensitive electrochemical sensor based on the molecularly imprinted polymer (MIP) was designed for measuring of Nevirapine (NVP). The non-imprinted polymer (NIP) and also MIP were synthesized then mixed with other compounds (graphite powder and paraffin oil) for the fabrication of the carbon paste electrodes (CPEs) to NVP analysis. The NIP/CP and MIP/CP electrodes were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) methods. The constructed sensor was utilized for NVP analysis using an oxidation peak of NVP in the square wave stripping voltammetry (SWSV) method. The calibration curve has consisted of a linear portion in the concentration range of 0.05–300 μM with the limit of detection (LOD) value of 10 nM. The MIP sensor demonstrated reproducible behavior and also, a high level of stability in all electrochemical experiments. Besides, analytical parameters were optimized, and the results were compared with similar results reported in the previous studies. The purposed sensor was successfully used for the quantitative measurement of this drug in the pharmaceutical dosage form and human blood serum samples.

Insights into the role of pyrrole doped in three-dimensional graphene aerogels for electrochemical sensing Cd(II)

In this work, three-dimensional graphene aerogels have been prepared by introduction of pyrrole to regulate their structure and properties and used as electrode materials to investigate the special role of pyrrole for sensing metal ions. The interaction between pyrrole and graphene oxide is explored through a series of characterization techniques to understand the role of doped pyrrole. Besides as N source to provide active metal ions binding sites, pyrrole can also serve as a reductant and a regulator to adjust the composition and structure of graphene aerogels, which greatly influences their electrochemical performance of sensing Cd(II). And, the reaction ratio of pyrrole and graphene oxide plays a key role to optimize the effect of pyrrole. By the method of square wave anodic stripping voltammetry (SWASV), the 3DGO-Py10 modified electrode can be successfully applied to determine Cd(II) in aqueous solutions. These findings will provide new guidelines to design electrode materials for heavy metal ions detection.

Development and validation of anodic stripping voltammetry method for the determination of tretinoin in human urine and plasma using glassy carbon electrode

Oxidation behavior of tretinoin (TRN) was evaluated using anodic stripping voltammetry (ASV), differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques in Britton-Robinson (B-R) pH 7. The glassy carbon (GC) electrode was used to deposit the compound (TRN) into its surface to record a well-defined oxidation peak at 0.75 V in the presence of Ag/AgCl reference electrode and a Pt counter electrode. Some analytical parameters were studied to obtain the best oxidation signal, for example; buffer solution, pH, accumulation potential and time, amplitude, frequency, scan rate and convection rate. The high sensitivity anodic peak was obtained using B-R, pH 7, 40 s accumulation time, −0.6 V accumulation potential, 50 mV amplitude, 20 Hz frequency, 350 mV s−1 scan rate, and 1000 rpm. These parameters were chosen as optimum conditions for the continued experiments. The analytical performance of the used technique was evaluated using the study of repeatability, stability, recovery, calibration curve and detection limit. Repeatability and stability was monitored for 5 × 10−6 mol L−1 of TRN to give 0.24% relative standard deviation (RSD%) for eighth anodic measurements, while the stability was been very well for 80 min. The calibration curve was studied over the range of 1 × 10−6–1 × 10−5 mol L−1 (n = 6), yielded, a linear relationship between concentrations and anodic current for TRN. A detection limit (LOD) was calculated to be 7.5 × 10−9 mol L−1 (2.25 ppb), while a quantification limit (LOQ) was yielded 2.49 × 10−8 mol L−1 (7.47 ppb). Anodic stripping voltammetry method was developed and applied for the determination of TRN in the human urine and plasma samples.

Controllable synthesis of an intercalated ZIF-67/EG structure for the detection of ultratrace Cd2+, Cu2+, Hg2+ and Pb2+ ions

The fabricated intercalated structure composed of a Co-based zeolitic imidazolate framework (ZIF-67) and expanded graphite (EG) has been prepared using a facile and simple one-pot hydrothermal reaction. This framework was used to detect heavy metal ions (HMIs) via a square wave anodic stripping voltammetry (SWASV) method for the first time. Here, the composite material is useful for the selective electrochemical detection of nanomolar Cd2+, Pb2+, Cu2+ and Hg2+ in aqueous solutions simultaneously or individually. The operational parameters such as pH, electrolyte, deposition potential, and deposition time were optimized to detect various HMIs. The electrochemical properties and applications of the modified electrode were also studied. The constructed electrochemical sensor displays good performance with a large electrochemically active surface areas, high sensitivity and low limit of detection (LOD). These impressive features originate from the synergistic effects of ZIF-67 and EG. This study proposes a new strategy for heavy metal ion detection using a novel morphology of a metal–organic framework (MOF) composite.

Validation of Method for Mercury Impurities Determination in Protamine Sulfate by Stripping Voltammetry

Introduction. The article presents the results of the validation of our developed method – stripping voltammetry (SVA) used for mercury impurities determination in protamine sulfate. Procedure was validated in terms of specificity, accuracy, precision (repetability and intermediate precision), and LLOQ. To confirm the results of the SVA method, we choose as comparative analyzes for mercury content determination in protamine sulfate generally accepted methods: atomic absorption spectroscopy (AAS), X-ray fluorescence spectrometry (XRF), and the pharmacopeia method according to the European Pharmacopoeia.Aim. Validation of method developed for mercury impurities determination in protamine sulphate by stripping voltammetry.Materials and methods. Protamine sulfate solution for injection 10 mg/mL (Novosibhimpharm», Novosibirsk, Russia) was used as a study object. The method of stripping voltammetry was performed at TA-4 semi-automatic analyzer (Tomanalit, Tomsk) with VALabTx software included. At the A. V. Nikolaev Institute of Inorganic Chemistry (Institute of Inorganic Chemistry SB RAS) atomic absorption spectroscopy was perfomed. At the Pacific State University was carried out X-ray fluorescence spectrometry. We carried out the pharmacopeia method in conjunction with «Novosibhimpharm» factory.Results and discussion. We validated the developed method for accuracy and precision. We evaluated the repetability by 10 measurements; the coefficient of variation was 7.8. We tested the intermediate precision for six measurements; the coefficient of variation was 7.9 and 7.4 for analyst № 1 and analyst № 2, respectively. According to our methodology, the mercury impurities content in protamine sulfate is 0.03 ppm. We compared our results with other generally accepted methods for the mercury determination in organic objects. When determining mercury by the AAS method, the result was ≤0.5 ppm, with XRF – 0.1 ppm. Pharmacopeia method results cannot be reliable due to the lack of repeatability.Conclusion. We validated the previously developed method for mercury impurities determination in protamine sulfate by stripping voltammetry. The results of our method are comparable with the results of other methods, such as AAS and XRF. That Therefore stripping voltammetry can be used in quality control of protamine drug products.

Determination of Trace Tl(I) by Differential Pulse Anodic Stripping Voltammetry Using a Novel Modified Carbon Paste Electrode

In this study, novel modifiers composed of multi walled carbon nanotubes (MWCNTs) and a series of noncyclic crown-type polyethers were prepared. The ligand loaded MWCNTs along with a room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluoro phosphate ([bmim][PF6]) were used for modification of a simple and low-cost carbon paste electrode (CPE). The modified CPE was employed for the determination of thallium(I) in aqueous medium using differential pulse anodic stripping voltammetry (DPASV) method. The effect of different experimental conditions such as supporting electrolyte, solution pH, accumulation potential, accumulation time, and modifier dosage were investigated and optimized. By DPASV, a linear dynamic range of 0.3–70 μg l−1 was achieved. The detection limit (3Sb) was found to be 0.08 μg l−1, below the maximum allowable limit (2 μg l−1) of the U.S. Environmental Protection Agency (USEPA). The present assay was also showed acceptable reproducibility with a relative standard deviation (RSD) value of 3.8% at 25.0 μg l−1 level (n = 7). The applicability of this electrode was successfully explored by measuring of thallium(I) in some natural waters without interference from sample matrix.

Copper nanoparticles incorporating a cationic surfactant-graphene modified carbon paste electrode for the simultaneous determination of gatifloxacin and pefloxacin

An original copper nanoparticle incorporating a cationic surfactant cetyltrimethylammonium bromide (CTAB)-graphene film had been successfully developed for the simultaneous determination of gatifloxacin and perflocacin with electrochemical method. The surface morphology of the nanocomposites was characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The synergistic effect of copper nanoparticles, graphene and CTAB surfactants increased the active site and enhanced the electrocatalytic ability of the modified carbon paste electrode. The modified electrode exhibited a good electrochemical behavior followed by well-separated oxidation peaks of gatifloxacin and perflocacin, the oxidation peak currents for gatifloxacin and perflocacin were found to vary linearly with their concentrations in the range of 0.02–40 μM and 0.04–20 μM with detection limits of 0.0021 μM and 0.0025 μM respectively using differential pulse stripping voltammetry (DPSV) method. The sensors have been applied to detect the residual of pefloxacin and gatifloxacin in the shrimp and animals serum with the satisfactory results, demonstrating that the film is one of the promising catalysts for electrocatalysis.