Britton-Robinson Buffer pH Research Articles

Extractive stripping voltammetry at a glassy carbon paste electrode for analysis of cow's milk and cream

In this paper, a procedure based on extractive accumulation of milk fat globules (MFGs) into a pasting liquid (lipophilic binder) of glassy carbon paste electrode (GCPE) with subsequent electrochemical detection by square-wave voltammetry (SWV) in 0.1 mol L-1 Britton-Robinson buffer of pH 4.0 has been tested to find out whether it can be utilized as a simple screening analytical method for cow's milk and cream nutrition control. Since there is assumption that the necessary alkaline hydrolysis of cow's milk and subsequent extraction of lipophilic vitamins into an organic solvent could be avoided, several GCPEs differing in type (atactic polypropylene, paraffin oil, paraffin wax, silicone oil, and vaseline) and content (5, 10, 15, 20, and 25%; w/w) of pasting liquid used were tested as part of complex optimization. The obtained results show that MFGs contain predominantly vitamin A (carotenoids and retinoids), especially all-trans-retinol, which could serve as significant marker of the fat content. However, their individual forms were not possible to distinguish due to the considerable anodic peak broadening (overlapping).

Voltammetric sensing of E,E-dienestrol in fish tissue by combining a cathodically pretreated boron-doped diamond electrode and QuEChERS extraction method

Food quality control has been a pressing issue in recent years and demands the development of efficient and versatile analytical methods. This paper describes a promising voltammetric assay to monitor the synthetic estrogen E,E-dienestrol (E,E-DNL) in fish tissue, using a cathodically pretreated boron-doped diamond (Cpt-BDD) electrode in combination with QuEChERS extraction method. The electrochemical reactivity of E,E-DNL on Cpt-BDD electrode is strongly pH-dependent, so that a well-defined anodic peak (≈ 0.97 V vs. Ag/AgCl) was recorded in Britton-Robinson buffer (pH = 2.0) due to oxidation of estrogen to quinone. This behavior became much more evident after cathodic pretreatment of the working electrode, since the hydrogen-terminations produced on the active surface improve the charge-transfer process, signal-to-background ratio and fouling resistance. When estrogen oxidation current was observed by square-wave voltammetry under optimum conditions, it was found a linear relationship from 2.30 × 10–7 to 9.69 × 10–6 mol L–1E,E-DNL, with high data correlation (R2 = 0.9987), sensitivity (detection limit of 5.43 × 10–8 mol L–1) and precision (RSD < 5.0% for repeatability and reproducibility tests) of the measurements. The procedure was successfully applied to quantify E,E-DNL in QuEChERS extracts from Nile Tilapia (Oreochromis niloticus) liver tissue (92.3–98.8% recovery), proving its high potential for the quality control of this estrogen in aquatic origin foods.

Amperometric sensor based on MWNT and electropolymerized carminic acid for the simultaneous quantification of TBHQ and BHA

Amperometric sensor based on the layer-by-layer combination of multi-walled carbon nanotubes and electropolymerized carminic acid deposited on the glassy carbon electrode surface (poly(carminic acid)/MWNT/GCE) has been developed for the simultaneous quantification of tert-butylhydroquinone (TBHQ) and butylated hydroxyanisole (BHA). Conditions of poly(carminic acid) coverage obtaining have been found on the basis of TBHQ and BHA peak potential separation and oxidation currents. The best parameters have been observed for poly(carminic acid) electrodeposited from 50 μmol L−1 monomer solution by seven-fold cycling of potential in the range of 0.3–0.8 V with the scan rate of 50 mV s−1 in Britton-Robinson buffer (BRB) pH 2.0. Electrodes have been characterized by scanning electron microscopy (SEM) and electrochemical methods. Good resolution of TBHQ and BHA oxidation potentials equalled to 190 mV has been obtained on the poly(carminic acid)/MWNT/GCE vs. 146 mV on MWNT/GCE. The oxidation currents are 2.1- and 1.8-fold increased on polymer-modified electrode for TBHQ and BHA, respectively. Parameters of TBHQ and BHA electrooxidation on poly(carminic acid)/MWNT/GCE have been calculated. Sensor response is linear in the range of 0.50–75 μmol L−1 for TBHQ and 0.25–75 μmol L−1 for BHA with the limits of detection of 0.36 and 0.23 μmol L−1, respectively. Sensor selectivity in the presence of inorganic ions, ascorbic acid and α-tocopherol is confirmed. The sensor developed has been tested on the linseed oil. The recovery of 100–103% confirm high accuracy of the approach.

Improved anodic stripping voltammetric detection of zinc on a disposable screen-printed gold electrode

Herein, we report the improved detection of Zn2+ via square-wave anodic stripping voltammetry utilizing an electrochemically treated screen-printed gold electrode. Surface analysis of the gold surface revealed increase in rugosity, removal of residual polymeric ink, and consequent higher access to gold microparticles after electrochemical treatment which resulted in improved response for Zn2+ (detection limit of 2.5 μg L− 1). The intra- and inter-electrode precision values were calculated as 3% (n = 10) and 12.5% (n = 3), respectively, applying − 0.9 V for 90 s under stirring of 1000 rpm for pre-concentration of Zn2+ (step potential: 4 mV; amplitude: 50 mV, frequency: 50 Hz) in 0.04 mol L− 1 Britton-Robinson buffer (pH 7.0) as the background electrolyte. Satisfactory recovery values ranging 96 to 104% were achieved for the analysis of struvite (spiked sample). Therefore, the proposed sensor provides precise and accurate direct analyses, without interference from other metals, with rapid responses enabling on-site analyses.

Improvement of adsorptive voltammetric methods for determination of Midodrine by carbon paste electrode modified with gold nano particles in presence of β-cyclodextrin

An effective novel electrochemical sensor constructed for the determination of Midodrine hydrochloride drug using differential pulse voltammetry. The sensor is based on a carbon paste electrode modified with gold nanoparticles and β-cyclodextrin in Britton-Robinson buffer of pH 3.0. The effect of various experimental parameters on the constructed electrodes properties including pH, β-cyclodextrin concentration and scan rate was investigated. At the optimum conditions, a linear range from 3.0 x 10-6 to 3.2 x 10-4 mol L-1 with correlation coefficient of 0.9997 and a detection limit of 5.14 x 10-7 mol L-1were obtained. The modified electrodes were used for microdetermination of the drug in tablets and spiked human urine samples with appropriate an acceptable recovery, reproducibility, selectivity and robustness. Potential strength investigation was achieved using 0.1 M of HCl.

Metallic Film Modified Screen-Printed Carbon Electrode for Determination of 17α-Methyltestosterone

17α-methyltestosterone (MT) is a synthetic androgen. It is used widely for inducing an all-male population of Nile tilapia (Oreochromis niloticus). In this work, the detection of MT was conducted using screen-printed carbon electrodes (SPCE). These were a bare electrode, a bismuth modified electrode (Bi-SPCE) and an antimony modified electrode (Sb-SPCE). The successful electrode modification was confirmed by scanning electron microscopy. The electroanalytical performance of the SPCE modified electrodes for MT detection was examined by cyclic voltammetry. The highest active surface area of 1.073x10-4 cm2 was obtained on Sb-SPCE. This indicates that Sb-SPCE can enhance the sensitivity of MT detection better than the bare-SPCE and the Bi-SPCE. The Sb-SPCE showed a linear response for MT concentrations ranging from 2 to 8 mg.L-1. The sensitivity obtained from the slope of a calibration curve was -0.452 mA.mol-1.L-1 in a Britton-Robinson buffer pH 4.0 containing Sb 16 mg.L-1 with deposition potential and deposition time of 1 V and 90 seconds, respectively. A linear relationship between the square root of the scan rate and the peak current revealed that mass transfer of MT to the electrode was driven by a diffusion mechanism. The limit of detection was found to be 1 mg.L-1.

Investigation of midazolam electro-oxidation on boron doped diamond electrode by voltammetric techniques and density functional theory calculations: Application in beverage samples

Midazolam (MID) is a sedative drug which can be added in beverage samples as drug-facilitated-sexual assault (date rape drug). This type of drug has short half-life in biological fluids (not detectable) which often prevents the correlation between drug abuse and crime. In this work, we described a simple and low-cost method for fast screening and selective determination of MID in beverage samples (vodka, whiskey and red wine). For the first time, the electrochemical oxidation of MID was used for this purpose. The oxidation mechanism was studied using electrochemical techniques (cyclic and square-wave voltammetry) and computational simulations (density functional theory calculations). Differential-pulse voltammetry, boron-doped diamond electrode (BDDE), and Britton-Robinson (BR) buffer (pH = 2) were selected as electrochemical analysis technique, working electrode and supporting electrolyte, respectively. Different linear response ranges (4–25 μmol L−1 with r = 0.9972; 1–10 μmol L−1 with r = 0.9951; 1–15 μmol L−1 with r = 0.9982) and limits of detection (0.46, 0.43 and 0.33 μmol L−1) were obtained for the analysis of vodka, whisky, and red wine solutions, respectively. The precision and accuracy were satisfactory considering the low relative standard deviation values (RSD < 6.3%, n = 15) and minimal sample matrix effects (recovery values between 87 and 103%).

Application of HPTLC, spectrofluorimetry and differential pulse voltammetry for determination of the antifungal drug posaconazole in suspension dosage form

This work presents the development, validation and application of three simple and direct analytical methods for determination of posaconazole (PSZ) in its pure form and in suspension dosage form. Method I is based on high performance thin layer chromatography (HPTLC) where effective separation of PSZ and the internal standard (itraconazole) was achieved using Merck HPTLC plates (20×10cm aluminium plates with 250μm layer thickness precoated with silicagel 60 F254) and a mobile phase composed of acetone and chloroform (1:2, by volume), followed by densitometric measurement of the drugs' spots at 262nm. Method II involves measurement of the native fluorescence of PSZ in 0.1M H2SO4 at excitation and emission wavelengths of 260 and 365nm, respectively. Method III depends on the voltammetric analysis of PSZ. A well-defined cathodic wave was obtained for PSZ in Britton-Robinson buffer pH 6.5 using the differential-pulse mode at the hanging mercury drop electrode (HMDE). The developed methods were validated according to the International Conference on Harmonization (ICH) guidelines regarding linearity, ranges, accuracy, precision, robustness and limits of detection and quantification. The proposed methods showed good linearity over the concentration ranges 5-50, 0.05-0.3, 0.005-0.05μg/mL PSZ for methods I, II, and III respectively. Intra and inter-day precision were verified by the RSD% values which were less than 2%. The proposed methods were successfully applied for the quantification of PSZ in suspension dosage form with no observable interferences. Assay methods were favorably compared with those obtained by previously reported HPLC method.

Doping Agent Naphazoline Hydrochloride: Development of Simple and Fast Voltammetric Method for Its Determination in Human Serum

Electrochemical behavior of naphazoline hydrochloride on a carbon paste electrode that was modified with aluminium oxide nanoparticles (Al2O3NPs) was investigated in a Britton-Robinson (BR) buffer (pH 7.0) using various voltammetric techniques. The results support the presence of an irreversible and diffusion-controlled electrochemical oxidation signal of naphazoline hydrochloride which is approximately at 0.9 V vs. Ag/AgCl. A selective, accurate, and simple square-wave anodic adsorptive stripping voltammetric method was purposed for naphazoline hydrochloride detection. The linear response was within the range of 5.0 × 10-8- 3.0 × 10-5 mol L-1 with a detection limit of 2.6 × 10–8 mol L–1 (0.0064 mg L–1). In addition, the purposed method was also utilized for naphazoline hydrochloride determination in human serum sample.

Voltammetric Determination of Cefuroxime Axetil in Pharmaceuticals Using Graphene Oxide Modified Glassy Carbon Electrode and Hanging Mercury Drop Electrode

Two novel, economic, rapid, simple, sensitive and selective square wave voltammetric (SWV) methods have been developed for the determination of cefuroxime axetil (CEFA) in pharmaceutical preparations. Electrochemical reduction and oxidation of the substance on hanging mercury drop electrode and graphene oxide modified glassy carbon electrode were investigated by square wave voltammetric methods which employ scan rates up to 1000 mV/s or faster, allowing much faster determinations. For hanging mercury drop electrode, well-defined peak was obtained at –1.06 V vs. Ag/AgCl/4.6 M KCl in 0.1 M phosphateborate buffer pH 7.0, limit of detection (LOD), limit of quantification (LOQ) and linearity range were found 0.09, 0.26, and 0.26–15 μg mL–1, respectively. For modified glassy carbon electrode, well-defined peak was obtained at 1.30 V vs. Ag/AgCl/4.6 M KCl in Britton–Robinson buffer pH 2.0, LOD, LOQ and linearity range were found 2.70, 8.20, and 8.20–45 μg mL–1, respectively. According to validation studies, the developed SWV methods were found as accurate, precise, specific, sensitive, repeatable, rugged and robust. The developed and validated SWV methods were applied to the determination of CEFA in pharmaceutical formulations. The results were compared with those obtained by a published ultraviolet spectroscopic method and no difference was found statistically.

Selective voltammetric determination of α-lipoic acid on the electrode modified with SnO2 nanoparticles and cetyltriphenylphosphonium bromide

Sensitive voltammetric method for α-lipoic acid determination based on glassy carbon electrode (GCE) modified with SnO2 nanoparticles (SnO2 NP) dispersion in cetyltriphenylphosphonium bromide (CTPPB) (SnO2 NP-CTPPB/GCE) has been developed. The comparison to other surface active compounds as dispersive agents has been performed. The electrodes surface has been characterized by scanning electron microscopy, electrochemical impedance spectroscopy, cyclic voltammetry, and chronoamperometry. Statistically significant decrease of charge transfer resistance (10.8 ± 0.4 kΩ vs. 181 ± 7 kΩ for GCE and 71 ± 3 kΩ for SnO2 NP-H2O/GCE) and higher effective surface area (13.7 ± 0.2 mm2 vs. 8.2 ± 0.3 mm2 for GCE and 12.1 ± 0.2 mm2 for SnO2 NP-H2O/GCE) has been obtained for SnO2 NP-CTPPB/GCE. α-Lipoic acid oxidation on SnO2 NP-CTPPB/GCE is a two-electron diffusion-controlled pH independent process leading to β-lipoic acid formation. Under conditions of differential pulse voltammetry in Britton–Robinson buffer pH 4.5, the linear dynamic ranges are 0.50–50 and 50–400 μmol dm−3 of α-lipoic acid with the limits of detection and quantification of 0.13 and 0.43 μmol dm−3, respectively. The method developed has been successfully applied for the pharmaceutical dosage form analysis.

Electrodeposition of 4-Benzenesulfonic Acid onto a Graphite-Epoxy Composite Electrode for the Enhanced Voltammetric Determination of Caffeine in Beverages.

Caffeine is widely present in food and drinks, such as teas and coffees, being also part of some currently commercialized medicines, but despite its enhancement on several functions of human body, its exceeding use can promote many health problems. In order to develop new fast approaches for the caffeine sensing, graphite-epoxy composite electrodes (GECE) were used as substrate, being modified by different diazonium salts, synthetized as their tetraflouroborate salts. An analytical method for caffeine quantification was developed, using sware wave voltammetry (SWV) in Britton–Robinson buffer pH 2.0. Detection limits for bare electrode and 4-benzenesulfonic modified electrode were observed circa 145 µmol·L−1 and 1.3 µmol·L−1, respectively. The results have shown that the modification shifts the oxidation peaks to lower potential. Kinetics of the reaction limited by diffusion was more expressive when caffeine was added to the solution, resulting in decreases of impedance, characterized by lower Rct. All results for caffeine determination were compared to a reference chromatographic procedure (HPLC), showing no statistical difference. Analytical parameters for validation were suitably determined according to local legislation, leading to a linear behaviour from 5 to 150 µmol·L−1; precision of 4.09% was evaluated based on the RDC 166/17, and accuracy was evaluated in comparison with the reference method, with recovery of 98.37 ± 2.58%.

Tunable ternary nanocomposite prepared by electrodeposition for biosensing of centrally acting reversible acetyl cholinesterase inhibitor donepezil hydrochloride in real samples

This paper describes the decoration of pencil graphite electrode (PGE) with a thin film of solochrome black T (SBT) and N-doped carbon nanodots (N-CNDs)/ cobalt nanoparticles (CoNPs) to amplify signal of the measurement. This nanocomposite was chosen to enhance surface activity and electron transfer toward donepezil HCl (DZ HCl) oxidation. The physical properties of nanocomposite were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), electron impedance spectroscopy (ESI) and energy dispersive X-ray (EDX) spectroscopy. Cyclic voltammetry was utilized to quantify DZ HCl at the modified PGE in Britton-Robinson buffer (pH = 6.5). Under optimized experimental conditions, peak current increased with the increase in the concentration of DZ HCl and was linear between the range of 1.5 nM–400 μM with a relatively low detection limit of 0.0005 μM. Due to high sensitivity, simplicity and cost-effectiveness of the designated sensor; it was used as a simple method for detecting DZ HCl in rabbit plasma and during its pharmacokinetic study.

Voltammetric study of valsartan–Ni complex: application to valsartan analysis in pharmaceuticals and in vivo human urine profiling

Valsartan (VAL) can be analyzed at the mercury electrode in the presence of nickel (II) yielding a sensitive cathodic peak at − 0.7 V which may be attributed to the reduction of the complex formed between nickel and VAL. Low LOD and LOQ were achieved (7.6 and 23 nM, respectively) permitting the analysis of VAL not only in its pharmaceutical formula, but also in human urine. The influence of adding transition metal, Ni(II), to the electrolyte containing VAL, on the voltammetric response was studied. Differential-pulse voltammetry, using working electrode: hanging mercury drop electrode (HMDE), was applied to elucidate and confirm the possible complexation reaction that could occur between VAL and nickel which aids in the determination of VAL in tablets and human urine. A simple cleanup procedure was applied for urine samples that involves the use of solid-phase extraction with the elution of VAL with methanol. The polarographic peak, which corresponds to the reduction of Ni(II) in the formed complex with VAL, was a function of the concentration of VAL, pH of the medium and Ni(II) concentration at the electrode surface. At Britton–Robinson buffer pH 6 and using 800 µM Ni(II), the reduction peak current linearly varied with the VAL concentration over the ranges of 25–150 and 25–200 nM in tablets as well as urinalysis, respectively.

Synthesis of Hydrotalcite-Supported CdTe Semiconductor Nanocrystals for Electrochemical Detection of Ciprofloxacin

In this work, CdTe quantum dots (QDs) were controllably grown onto the surface of layered double hydroxide (LDH) aiming to develop a sensitive and selective method for the electrochemical detection of ciprofloxacin (CPX). Emission and absorption spectroscopy results as well as high-resolution transmission electron microscopy (HRTEM) images evidenced the formation of LDH/QD hybrid material. Unmodified carbon paste electrodes (CPE) as well as CPE chemically modified (MCPE) with native LDH and with the LDH/QD hybrid were prepared for CPX detection, revealing that MCPE-LDH/QD had the highest sensitivity for the detection of ciprofloxacin. Optimum detection conditions included a modifier dosage of 20% in MCPE, Britton-Robinson (BR) buffer (pH 6.0) as analytical medium, 300 s accumulation time and a scanning rate of 20 mV s-1. Linear current versus concentration curve was observed from 2.5 × 10-8-1.2 × 10-5 mol L-1 (coefficient of determination (R2) = 0.995), with sensitivity (limit of detection (LOD) = 4.2 × 10-8 mol L-1; limit of quantification (LOQ) = 1.3 × 10-7 mol L-1), precision (relative standard deviation (RSD) = 3.0%), accuracy (94.0%) and satisfactory selectivity in the presence of Zn2+, Fe2+, Cu2+, citric acid and ascorbic acid. Tests of CPX determination in commercial 500 mg ciprofloxacin tablets evidenced the applicability of the method.

Electrochemical oxidation of ranitidine at poly(dopamine) modified carbon paste electrode: Its voltammetric determination in pharmaceutical and biological samples based on the enhancement effect of anionic surfactant

The preparation and characterization of a carbon paste electrode modified with poly(dopamine) as well as its novel application for the electrochemical oxidation and voltammetric determination of ranitidine are described. The sensitivity of the voltammetric measurements was significantly increased at modified electrode in comparison to the bare one. Besides, a further increase in the detecting sensitivity of ranitidine could be obtained in the presence of anionic surfactant (sodium dodecylsulfate). Using square-wave voltammetry, the drug yielded a well-defined voltammetric response in Britton-Robinson buffer (pH 5.0) containing 1 × 10−3 M sodium dodecylsulfate at +0.96 V (vs. Ag/AgCl). The process could be used to determine ranitidine in the concentration range from 1 × 10−7 to 7.5 × 10−6 M, with a detection limit of 1.9 × 10−8 M (6.1 ng mL−1). The suggested method was successfully applied to pharmaceuticals and spiked human urine samples.

Sequential injection analysis for the determination of fluoroquinolone antibacterial drug residues by using eosin Y as complexing agent

A sequential injection analysis (SIA) method was developed for the rapid and sensitive determination of fluoroquinolone residues, including norfloxacin, ciprofloxacin and enrofloxacin, in fish samples. The method is based on the reaction between fluoroquinolone drug and eosin Y in Britton-Robinson buffer (pH 2.0), forming pink colored complexs with maximum absorptions at 522, 525 and 527 nm for norfloxacin, ciprofloxacin and enrofloxacin, respectively. Linearity ranges were found to be 0.05–10.0 mg L−1 (r2 = 0.9996), 0.1–10.0 mg L−1 (r2 = 0.9995) and 0.05–10.0 mg L−1 (r2 = 0.9997) for norfloxacin, ciprofloxacin and enrofloxacin, respectively. The detection limit was found to be in the range of 0.013–0.019 mg L−1. The method was tested and validated for various parameters according to main guidelines. The proposed SIA method was successfully applied for the determination of fluoroquinolone drug residues in fish samples with the sampling rate of 47 h−1. The results demonstrated that the method is accurate, precise and reproducible, while being simple, rapid, economical and less time consuming. It can be suitably applied for the estimation of fluoroquinolone drug residues in routine quality control.

Design, Fabrication, and Optimization of Polypyrrole/Bismuth Oxide Nanocomposite as Voltammetric Sensor for the Electroanalysis of Clofazimine

The highly sophisticated and conducting Polypyrrole/Bismuth Oxide nanocomposite material was designed, fabricated, characterized and optimized as a novel voltammetric sensor for the electroanalysis of clofazimine (CFZ). The designing and fabrication of voltammetric sensor were reached by the synthesis of Ppyl/Bi2O3 nanocomposite for the modification of glassy carbon electrode (GCE). Prior to the fabrication of Ppyl/Bi2O3/GCE sensor, the Ppyl/Bi2O3 nanocomposite material along with its constituents Ppyl and Bi2O3 were characterized by FTIR, XRD and scanning electron microscopy (SEM). The cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used to determine the surface area, heterogeneous electron transfer (HET) rate constant and charge transfer resistance of the bare GCE and its other modified forms viz., Bi2O3/GCE, Ppyl/GCE including the Ppyl/Bi2O3/GCE sensor to confirm the successful fabrication by comparing their electrocatalytic activities toward the CFZ. The Ppyl/Bi2O3/GCE sensor after optimization in Britton-Robinson buffer of pH 2.5 in ethanol exhibited a well-defined reduction peak varying linearly over a concentration range of 21.12 μmol/mL to 253.49 μmol/mL with a correlation coefficient (r2) of 0.99. The designed sensor shows the highest sensitivity in terms of the limit of detection (LOD) and the limit of quantification (LOQ) found to be 0.97 μmol/mL and 3.23 μmol/mL respectively. The optimized sensor also reveals the exceptional reproducibility with a relative standard deviation (RSD) of 1.20%, satisfactory recovery of 100.04% to 103.20% and long-term stability.

Simultaneous Electrochemical Determination of Articaine HCl and Epinephrine

A simple, precise, accurate and inexpensive voltammetric method was developed for the simultaneous determination of articaine HCl and epinephrine in bulk, pharmaceutical formulations and human urine at carbon paste electrode in Britton-Robinson buffer of pH 7 and 40 μL of 10−2 mol L−1 sodium dodecyl sulphate. Several factors were studied such as buffer type, pH, surfactant, scan rate, and accumulation time to obtain the optimum conditions for analysis. The method showed linearity in concentration range of 1.0 × 10−6-2.6 × 10-5 mol L−1. The limits of detection and quantitation were found 2.88 × 10−7 mol L−1 and 8.72 × 10−7 mol L−1 for articaine HCl and 5.10 × 10−8 mol L−1 and 1.56 × 10-7 for epinephrine, respectively. The proposed voltammetric method was successfully applied for simultaneous determination of articaine HCl and epinephrine in bulk, injections and urine. The results obtained from the proposed method were statistically compared with those of a reported method and showed no significant difference. Thus, it can be used as quality control in laboratories.

DETERMINATION OF HYDROXYZINE BY DIFFERENTIAL PULSE ANODIC VOLTAMMETRY USING CARBON PASTE ELECTRODE

The electrochemical oxidation of hydroxyzine dihydrochloride at carbon paste electrode has been studied in 0.04 M Britton-Robinson buffer pH 6.2 using cyclic and differential pulse voltammetry. The oxidation process has been shown to irreversible and diffusion controlled with adsorption characterstics. Based on these studies, simple, rapid, and sensitive differential pulse anodic voltammetric method has been developed for the determination of the drug over the concentration range 0.45-5.36 μg/ml, with detection and quantification limits of 0.27 and 0.90 μg/ml hydroxyzine dihydrochloride, respectively. The proposed method was successfully used for quantification of hydroxyzine dihydrochloride in Atarax tablets and spiked human urine.