Voltammetric and differential pulse determination of roxithromycin

The oxidative behavior of antibiotic roxithromycin standard was studied at a gold electrode in 0.05 M NaHCO₃ using cyclic linear sweep voltammetry and differential pulse voltammetry. It was found that the value of the oxidative peak of pure roxithromycin at 0.81 V vs. SCE in 0.05 M NaHCO₃ at a scan rate of 50 mV s⁻¹ is a linear function of the concentration in a range 0.10006-0.654 mg cm⁻³. It was also found that peak current density at 0.75 V vs. SCE at a scan rate of 2 mV s⁻¹, pulse amplitude of 25 mV and pulse time of 0.1 s exhibits linear dependence on the concentration of roxithromycin from 0.1006 to 0.476 mg cm⁻³. Roxithromycin as a content of solid dosage form and urine was quantitatively determined and the obtained results were checked by HPLC.     

Electrooxidation of sulfide by cobalt pentacyanonitrosylferrate film on glassy carbon electrode by cyclic voltammetry

A glassy carbon (GC) electrode was modified with cobalt pentacyanonitrosylferrate (CoPCNF) film. Cyclic voltammetry (CV) of the CoPCNF onto the GC (CoPCNF/GC) shows a redox couple (Fe^III/Fe^II) with a standard potential (E^0′) of 580 mV. The current ratio I_pa/I_pc remains almost 1, and a peak separation (ΔE_p) of 106 mV is observed in 0.5 M KNO₃ as the supporting electrolyte. Anodic peak currents were found to be linearly proportional to the scan rate between 10 and 200 mV s⁻¹, indicating an adsorption-controlled process. The redox couple of the CoPCNF film presents an electrocatalytic response to sulfide in aqueous solution. The analytical curve was linear in the concentration range of 7.5 × 10⁻⁵ to 7.7 × 10⁻⁴ M with a detection limit of 4.6 × 10⁻⁵ M for sulfide ions in 0.5 M KNO₃ solution.     

Electrooxidation of glyphosate herbicide at different DSA compositions: pH, concentration and supporting electrolyte effect

This paper has investigated the electrochemical oxidation of glyphosate herbicide (GH) on RuO₂ and IrO₂ dimensionally stable anode (DSA^®) electrodes. Electrolysis was achieved under galvanostatic control as a function of pH, GH concentration, supporting electrolyte, and current density. The influence of the oxide composition on GH degradation seems to be significant in the absence of chloride; Ti/Ir_0.30Sn_0.70O₂ is the best electrode material to oxidize GH. GH oxidation is favored at low pH values. The use of chloride medium increases the oxidizing power and the influence of the oxide composition is meaningless. At 30 mA cm⁻² and 4 h of electrolysis, complete GH removal from the electrolyzed solution has been obtained. In chloride medium, application of 50 mA cm⁻² leads to virtually total mineralization (release of phosphate ions = 91%) for all the evaluated oxide materials.     

Chitosan membranes filled by GPTMS-modified zeolite beta particles with low methanol permeability for DMFC

Uniform zeolite beta particles about 800 nm in diameter were synthesized by a hydrothermal method, and functionalized by γ-glycidoxypropyltrimethoxysilane (GPTMS). Subsequently, chitosan (CS) membranes filled by GPTMS-modified zeolite beta particles were prepared, and characterized by SEM, FT-IR, XRD and TGA. Compared with the pure CS and Nafion^®117 membrane, these CS/zeolite beta hybrid membranes show apparently the lower methanol permeability, which could be assigned to the better interfacial morphology and compatibility between the GPTMS-modified zeolite beta particles and chitosan matrix. In all the prepared CS/zeolite beta hybrid membranes, the CS membrane filled by 10 wt.% GPTMS-modified zeolite beta particles exhibits the lowest methanol permeability, which is 4.4 × 10⁻⁷ and 2.2 × 10⁻⁷ cm² s⁻¹ at 2 and 12 M methanol concentration, respectively. The proton conductivity of this hybrid membrane is 1.31 × 10⁻² S cm⁻¹, which is slightly lower than that of the pure CS membrane. The selectivity of CS/GPTMS-zeolite beta membranes is comparable with Nafion^® 117 at 2 M methanol concentration, and much higher at 12 M methanol concentration.     

Poly(vinyl alcohol)-based polymer electrolyte membranes for direct methanol fuel cells

We have prepared polymer electrolyte membranes (PEMs) from poly(vinyl alcohol) (PVA) and modified PVA polyanion containing 2 or 4 mol% of 2-methyl-1-propanesulfonic acid (AMPS) groups as a copolymer. The PEMs of various AMPS content and cross-linking conditions were prepared to determine the effect of AMPS content and cross-linking conditions on PEM properties. Proton conductivity and permeability of methanol through the PEMs increased with increasing AMPS content, C_AMPS, and with decreasing cross-linker concentration, C_GA, because of the increase in the water content. The permeability coefficient of methanol through the PEM prepared under the conditions of C_AMPS = 2.7 mol% and C_GA = 0.35 vol% was about 30 times lower than that of Nafion^®117 under the same measurement conditions. The proton permselectivity of the PEM, which is defined as the ratio of the proton conductivity to the permeability coefficient of methanol, gave a maximum value of 66 × 10³ S cm⁻³ s. The value is about three times higher than that of Nafion^®117.     

Distribution profile of water and suppression of methanol crossover in sulfonated polyimide electrolyte membrane for direct methanol fuel cells

We have developed novel cross-linked sulfonated polyimide (c-SPI) membrane as an electrolyte for direct methanol fuel cells (DMFCs). When the DMFC using the c-SPI membrane (thickness = 155 μm), Pt-Ru dispersed on carbon black (Pt-Ru/CB) anode and Pt/CB cathode with a Nafion^® ionomer was operated at 80 °C and 0.1 A cm⁻² with 1 M CH₃OH and oxygen (oxidant), the methanol crossover rate, j(CH₃OH), was suppressed to about 1/2 compared with that of the Nafion^® 117 membrane (thickness = 180 μm) with the same electrodes. It was found for both cells that the j(CH₃OH) was not so small as expected from the membrane thickness. In order to obtain a clue for the suppression of j(CH₃OH), the distribution profiles of water (containing CH₃OH) in thickness direction were investigated by measuring the specific resistances (ρ) between Pt probes inserted into the electrolyte membrane. Values of ρ at the anode side were low irrespective of the discharge current density, because such a part of the membrane was humidified thoroughly by liquid water (1 M CH₃OH) allowing free penetration of CH₃OH into the swollen polymer. In contrast, the values of ρ at the cathode side were high at the low current density due to drying of the membrane contacting with oxidant gas (O₂ or air) in low humidity. We have succeeded to suppress the j(CH₃OH) further (about 1/2 at 0.2 A cm⁻²) by using bilayer c-SPI, having a low ion exchanging (low swelling) barrier layer at the anode side without increasing the ohmic resistance, compared with that of the single c-SPI.     

Use of novel permeable membrane and air cathodes in acetate microbial fuel cells

In the existing microbial fuel cells (MFCs), the use of platinized electrodes and Nafion^® as proton exchange membrane (PEM) leads to high costs leading to a burden for wastewater treatment. In the present study, two different novel electrode materials are reported which can replace conventional platinized electrodes and can be used as very efficient oxygen reducing cathodes. Further, a novel membrane which can be used as an ion permeable membrane (Zirfon^®) can replace Nafion^® as the membrane of choice in MFCs. The above mentioned gas porous electrodes were first tested in an electrochemical half cell configuration for their ability to reduce oxygen and later in a full MFC set up. It was observed that these non-platinized air electrodes perform very well in the presence of acetate under MFC conditions (pH 7, room temperature) for oxygen reduction. Current densities of −0.43 mA cm⁻² for a non-platinized graphite electrode and −0.6 mA cm⁻² for a non-platinized activated charcoal electrode at −200 mV vs. Ag/AgCl of applied potential were obtained. The proposed ion permeable membrane, Zirfon^® was tested for its oxygen mass transfer coefficient, K₀ which was compared with Nafion^®. The K₀ for Zirfon^® was calculated as 1.9 × 10⁻³ cm s⁻¹.     

The stability of an acidic tin methanesulfonate electrolyte in the presence of a hydroquinone antioxidant

The electrodeposition of tin at a (0.28 cm²) copper surface from 0.014 mol dm⁻³ SnSO₄ and 12.5 vol.% methanesulfonic acid (MSA 1.93 mol dm⁻³) at 296 K was studied. Hydroquinone concentrations of 0.005, 0.05 and 0.5 mol dm⁻³ (corresponding to a molar concentration ratio of hydroquinone to stannous ions of 0.36, 3.6 and 36, respectively) were used. Cyclic and linear sweep voltammetry served to characterise the electrochemical behaviour of tin deposition and stripping. The effects of potential sweep rate and electrode rotation speed on the voltammetry were studied. The stability of the electrolyte with storage time was quantified by changes in the limiting current density for tin deposition at a smooth rotating disc electrode and the peak current density at a static disc electrode. The influence of hydroquinone on mass transport controlled tin deposition and suppression of hydrogen evolution was evaluated.     

A solar regenerable cathodic electron acceptor for microbial fuel cells

In this study, a high performance and solar regenerable cathodic electron acceptor, I₃⁻, was incorporated into a microbial fuel cell (MFC). Linear sweep voltammetry showed that a current density of 4.2 mA cm⁻² can be obtained from the electroreduction of I₃⁻. This value was approximately twice that of ferricyanide (Fe(CN)₆³⁻) and was independent of the pH of the electrolyte. The effect of regeneration conditions, such as the pH of the KI solution, KI concentration, oxygen flow rate and the Xe light intensity, on the I₃⁻ yield and performance of the MFC was investigated. A sufficient supply of I₃⁻ was achieved when the concentration of an air-saturated KI solution was greater than 0.2 M and its pH was around 2.0, under an irradiation higher than 300 mW cm⁻². Extended operation of the MFC showed that I₃⁻ is capable of supporting the MFC for long-term electricity generation. The maximum power output of the MFC using a catholyte containing 1.2 mM I₃⁻ + 0.2 M KI solution was 484.0 mW m⁻². This performance was greater than that (307.1 mW m⁻²) when using a catholyte containing 1.2 mM Fe(CN)₆³⁻ + 0.2 M KCl solution under the same conditions.     

Studies on the electrochemical behavior of 3-nitrobenzaldehyde thiosemicarbazone at glass carbon electrode modified with nano-γ-Al2O3

Nano-γ-Al₂O₃ is dispersed onto the glass carbon electrode (GCE) by polishing. This nanostructured modified GCE exhibits a great enhancement to the redox responses of 3-nitrobenzaldehyde thiosemicarbazone (3-NBT). In comparison with bare GCE, 3-NBT gives a more sensitive voltammetric response because of the nanoparticle’s unique properties. The lowest detectable concentration (3σ) of 3-NBT is estimated to be 1.18 × 10⁻⁶ M (accumulation for 4 min). The linear relationship between peak current and concentration of 3-NBT holds in the range 1.0 × 10⁻⁵ M to 1.0 × 10⁻⁴ M (r = 0.9981). The electrochemical properties of 3-NBT on this modified electrode have been investigated with various electrochemical methods. The results indicate that the transference of one electron and one proton involves electrode radical reaction processes I and II, respectively. The coverage value (Γ) of 1.62 × 10⁻⁹ mol cm⁻² was calculated and the electrochemical parameters, diffusion coefficient D (2.54 × 10⁻³ cm² s⁻¹, 2.03 × 10⁻³ cm² s⁻¹) and reaction rate constant k_s (5.9573 s⁻¹, 7.15 × 10⁻² cm s⁻¹) were obtained for quasi-reversible system I and irreversible system II, respectively.     

Increasing ionic conductivity and mechanical strength of a plastic electrolyte by inclusion of a polymer

In this contribution we present a soft matter solid electrolyte which was obtained by inclusion of a polymer (polyacrylonitrile, PAN) in LiClO₄/LiTFSI-succinonitrile (SN), a semi-solid organic plastic electrolyte. Addition of the polymer resulted in considerable enhancement in ionic conductivity as well as mechanical strength of LiX-SN (X = ClO₄, TFSI) plastic electrolyte. Ionic conductivity of 92.5%-[1 M LiClO₄-SN]:7.5%-PAN (PAN amount as per SN weight) composite at 25 °C recorded a remarkably high value of 7 × 10⁻³ Ω⁻¹ cm⁻¹, higher by few tens of order in magnitude compared to 1 M LiClO₄-SN. Composite conductivity at sub-ambient temperature is also quite high. At −20 °C, the ionic conductivity of (100 − x)%-[1 M LiClO₄-SN]:x%-PAN composites are in the range 3 × 10⁻⁵-4.5 × 10⁻⁴ Ω⁻¹ cm⁻¹, approximately one to two orders of magnitude higher with respect to 1 M LiClO₄-SN electrolyte conductivity. Addition of PAN resulted in an increase of the Young's modulus (Y) from Y → 0 for LiClO₄-SN to a maximum of 0.4 MPa for the composites. Microstructural studies based on X-ray diffraction, differential scanning calorimetry and Fourier transform infrared spectroscopy suggest that enhancement in composite ionic conductivity is a combined effect of decrease in crystallinity and enhanced trans conformer concentration.     

EDLC performance of carbide-derived carbons in aprotic and acidic electrolytes

This study shows that carbide-derived carbons (CDCs) with average pore size distributions around 0.9-1 nm and effective surface areas of 1300-1400 m² g⁻¹ provide electrochemical double-layer capacitors with high performances in both aqueous (2M H₂SO₄) and aprotic (1M (C₂H₅)₄NBF₄ in acetonitrile) electrolytes.In the acidic electrolytic solution, the gravimetric capacitance at low current density (1 mA cm⁻²) can exceed 200 F g⁻¹, whereas the volumetric capacitance reaches 90 F cm⁻³. In the aprotic electrolyte they reach 150 F g⁻¹ and 60 F cm⁻³.A detailed comparison of the capacitive behaviour of CDCs at high current density (up to 100 mA cm⁻²) with other microporous and mesoporous carbons indicates better rate capabilities for the present materials in both electrolytes. This is due to the high surface area, the accessible porosity and the relatively low oxygen content.It also appears that the surface-related capacitances of the present CDCs in the aprotic electrolyte are in line with other carbons and show no anomalous behaviour.     

Studies on electrochemical properties of MWNTs-Nafion composite films based on the redox behavior of incorporated Eu by voltammetry and electrochemical impedance spectroscopy

MWNTs can be conveniently dispersed in Nafion solution on the basis of the special interactions between the sidewall of MWNTs and the hydrophobic domains of Nafion. Casting of the resulting mixture on electrode surfaces produced uniform composite films having wide electroanalytical applications. In this work, the electrochemical properties of the MWNTs-Nafion composite film on a glassy carbon electrode were systematically investigated by various electrochemical methods using incorporated europium(III) ions (Eu³⁺) as the probe. The voltammetric studies showed that the increase of MWNTs concentration in the composite film could effectively improve the redox currents of Eu³⁺ and reduce the peak separation, whereas the increase of Nafion concentration generally increased both the redox currents and the peak separation. These results suggested the different roles of MWNTs and Nafion in the composite films. The electrochemical impedance spectroscopic (EIS) investigations showed that MWNTs mainly contributed to the charge transfer and mass transfer processes of the composite film through the increases of the electrode/electrolyte interfacial area and the film porosity while Nafion generally dominated the mass transport from the solution into the film via ion exchange. The potential application of the sensitive response of Eu³⁺ at the MWNTs-Nafion composite film in electroanalytical chemistry was evaluated. In the range of 0.04-100 μM, the concentration of Eu³⁺ showed excellent linear relationships with the differential pulse voltammetric response with a low detection limit of 10 nM (S/N = 3) for 60 s accumulation at −0.1 V.     

Electrochemical study of a hydrogen diffusion anode-membrane assembly for membrane electrolysis

The membrane electrode assembly (MEA) studied was constituted with a gas diffusion electrode (E-TEK) impregnated with Nafion^® solution which was assembled with a Nafion^® 117 cation exchange membrane under heat and pressure. The MEA was used as anode in a membrane electrolysis (ME) cell with the objective to regenerate HCl and NaOH from NaCl. Current efficiency for hydrogen oxidation was determined and its value is 100%, which indicates that the only reaction occurring at the anode is the oxidation of hydrogen. Current-potential curves, recorded in different conditions, showed a linear variation in the range 0-3000 A m⁻² when hydrochloric acid concentration is below 2 mol dm⁻³. In this case, the overvoltage was shown to be mainly due to the ohmic drop in the membrane and in the layer where Nafion^® impregnation was performed. MEA overvoltage necessary to reach 3000 A m⁻² current density was about 0.12 V. For high HCl concentration (6-8 mol dm⁻³), the MEA overvoltage increased sharply with current density due to the adsorption of chloride anions on platinum catalyst.     

Effects of phosphate species on localised corrosion of steel in NaHCO3 + NaCl electrolytes

Pitting corrosion of carbon steel electrodes in 0.1 M NaHCO₃ + 0.02 M NaCl solutions was induced by anodic polarisation. The evolution of the breakdown potential E_b with the phosphate concentration was investigated by linear voltammetry. E_b increased from −15 ± 5 mV/SCE for [HPO₄²⁻] = 0 to 180 ± 40 mV/SCE for [HPO₄²⁻] = 0.02 mol L⁻¹. During anodic polarisation (E = 50 mV/SCE), the behaviour of the whole electrode surface, followed by chronoamperometry, was compared to the behaviour of one single pit, followed via the scanning vibrating electrode technique (SVET). The addition of a Na₂HPO₄ solution after the beginning of the polarisation did not lead to the repassivation of pre-existing well-grown pits. The corrosion products forming in the pits were identified in situ by micro-Raman spectroscopy. They depended on the phosphate concentration. For [HPO₄²⁻] = 0.004 mol L⁻¹, siderite FeCO₃ was detected first. It was oxidised later into carbonated green rust GR(CO₃²⁻) by dissolved O₂. The beginning of the process is therefore similar to that observed in the absence of phosphate. Finally, GR(CO₃²⁻) was oxidised into ferrihydrite, the most poorly ordered form of Fe(III) oxides and oxyhydroxides. Phosphate species, adsorbing on the nuclei of FeOOH, inhibited their growth and crystallisation. For [HPO₄²⁻] = 0.02 mol L⁻¹, siderite was accompanied by an amorphous precursor of vivianite, Fe₂(PO₄)₃·8H₂O. This shows that, in any case, phosphate species interact strongly with the iron species produced by the dissolution of steel.     

Electrolytic conductivity—the hopping mechanism of the proton and beyond

The hopping mechanism of electrolytic conductivity is analyzed, employing mixtures of two solvents: one that sustains the hopping mechanism and the other that does not inhibit it directly, but interferes with it by diluting the solvent that sustains hopping.Measurement of the equivalent conductivity shows that the excess proton conductivities of H₃O⁺ and OH⁻ increases with increasing temperature, although the number of hydrogen bonds is known to decrease.In mixtures of acetonitrile with water, proton hopping does not start until a threshold concentration of about 20 vol.% water has been reached, while no such threshold concentration is observed upon addition of methanol to acetonitrile. It is concluded that in the former the proton is transferred to a cluster of water molecules, which can be formed only if there is enough water in the solvent mixture. This observation leads to the concept of mono-water, which is the state of water molecules when they constitute a small minority in the solvent mixtures, as opposed to bulk water, which consists of clusters of variable sizes.Systems in which a hopping mechanism of heavy ions has been observed include Br⁻/Br₂ and I⁻/I₂. In these cases the triple ions Br₃⁻ and I₃⁻, respectively are formed, and serve as the mediators for the transfer of the simple halogen ion. A very large increase of conductivity was observed upon solidification of the Br⁻/Br₃⁻ system, probably caused by favorable linear alignment of ions in the solid.The conductivity of acidified methanol decreases upon addition of water, because the affinity of the proton to water is higher than to methanol, thus water can act as a scavenger for protons. This behavior exemplifies a general observation, namely that conductivity by hopping can only occur when the Gibbs energy of the system does not change significantly following ion transfer; otherwise the ions would be trapped in the more stable state, hindering further propagation by hopping.The dependence of the Walden product on temperature can serve as an experimental criterion for hopping. A distinct decline of the product λ⁰ × η with increasing temperature is a clear indication of the occurrence of a hopping (non-Stokesian) mechanism of electrolytic conductivity.     

Influence of Nafion film on oxygen reduction reaction and hydrogen peroxide formation on Pt electrode for proton exchange membrane fuel cell

The influence of Nafion^® film on ORR kinetics and H₂O₂ formation on a Pt electrode was investigated using RRDE in 0.1 M HClO₄. It was found that the Nafion^®-coated Pt system showed lower apparent ORR activity and more H₂O₂ production than the bare Pt electrode system. From the temperature sensitivity, it was revealed that the apparent activation energies of ORR in the Nafion^®-coated Pt system were lower than the bare Pt electrode system, and the H₂O₂ formation was suppressed with the increase of the temperature. In order to analyze the results furthermore, other systems (0.1/1.0 M, HClO₄/CF₃SO₃H) with the bare Pt electrodes were also examined as references. It was exhibited that the ORR kinetic current, the H₂O₂ formation, and the apparent activation energies of 1.0 M CF₃SO₃H system were close to those of the Nafion^®-coated Pt system. We concluded that the orientation of anion species of Nafion^® and CF₃SO₃H to the Pt surface via water molecules, as well as a fluorocarbon polymer network of Nafion^®, might block O₂ adsorption, resulting in the smaller effective surface area of the Pt electrode for ORR, the smaller ORR kinetic current, and the more H₂O₂ production.     

High sensitive simultaneous determination of catechol and hydroquinone at mesoporous carbon CMK-3 electrode in comparison with multi-walled carbon nanotubes and Vulcan XC-72 carbon electrodes

The simultaneous voltammetric determination of catechol (CC) and hydroquinone (HQ) has been achieved at a mesoporous carbon CMK-3 modified electrode in phosphate buffer solution (pH 7.0). At the electrode both CC and HQ can cause a pair of quasi-reversible and well-defined redox peaks and their peak potential difference increases. In comparison with multi-walled carbon nanotubes (MWCNTs) and Vulcan XC-72 carbon modified electrodes the CMK-3 modified electrode shows larger peak currents and higher adsorbed amounts for the two dihydroxybenzene isomers. This is related to the higher specific surface area of CMK-3. Under the optimized conditions, the linear concentration ranges for CC and HQ are 5 × 10⁻⁷ to 3.5 × 10⁻⁵ M and 1 × 10⁻⁶ to 3 × 10⁻⁵ M, respectively. In the presence of 5 μM isomer, the linear concentration range of CC (or HQ) is 5 × 10⁻⁷ to 2.5 × 10⁻⁵ M (or 5 × 10⁻⁷ to 2.0 × 10⁻⁵ M). The sensitivity for CC or HQ is 41 A M⁻¹ cm⁻² or 52 A M⁻¹ cm⁻², which is close to that without isomer. The detection limits (S/N = 3) for CC and HQ are 1 × 10⁻⁷ M after preconcentration on open circuit for 240 s.     

Electrochemical behaviour of titanium in H2SO4-MnSO4 electrolytes

The corrosion of titanium in H₂SO₄ electrolytes (0.001-1.0 M) at temperatures from ambient to 98 °C has been investigated using steady-state polarization measurements. Four distinct regions of behaviour were identified, namely active corrosion, the active-passive transition, passive region and the dielectric breakdown region. The active corrosion and active-passive transition were characterized by anodic peak current (i_m) and voltage (E_m), which in turn were found to vary with the experimental conditions, i.e., d(log?(im))/dpH=−0.8±0.1 and dE_m/dpH which was −71 mV at 98 °C, −58 mV at 80 °C and −28 mV at 60 °C. The activation energy for titanium corrosion, determined from temperature studies, was found to be 67.7 kJ mol⁻¹ in 0.1 M H₂SO₄ and 56.7 kJ mol⁻¹ in 1.0 M H₂SO₄. The dielectric breakdown voltage (E_d) of the passive TiO₂ film was found to vary depending on how much TiO₂ was present. The inclusion of Mn²⁺ into the H₂SO₄ electrolyte, as is done during the commercial electrodeposition of manganese dioxide, resulted in a decrease in titanium corrosion current, possibly due to Mn²⁺ adsorption limiting electrolyte access to the substrate.     

Anodic voltammetry of abacavir and its determination in pharmaceuticals and biological fluids

Abacavir has an antiretroviral activity against HIV and is oxidizable at the glassy carbon electrode. Cyclic voltammetry studies showed one well-defined oxidation wave or splitted two waves depending on pH. The oxidation was irreversible and exhibited diffusion controlled process depending on pH. The mechanism of the oxidation process was discussed. According to the linear relation between the peak current and the concentration, differential pulse voltammetric (DPV) and square wave voltammetric (SWV) methods for its quantitative determination in pharmaceutical dosage forms and biological fluids were developed. These two voltammetric techniques for the determination of abacavir in Britton-Robinson buffer at pH 2.0, which allows quantitation over the 8×10⁻⁷ to 2×10⁻⁴ M range in supporting electrolyte for both methods were proposed. The linear response was obtained in Britton-Robinson buffer in the ranges of 1×10⁻⁵ to 1×10⁻⁴ M for spiked urine sample at pH 2.0 and 2×10⁻⁵ to 2×10⁻⁴ M for spiked serum samples at pH 3.0 for both techniques. The repeatability and reproducibility of the methods for all media (such as supporting electrolyte, serum and urine samples) were determined. Precision and accuracy were also checked in all media. The standard addition method was used in biological media. No electroactive interferences from the endogenous substances were found in the biological fluids.