ELECTROCHEMICAL DETERMINATION OF KETOROLAC - A NON-OPIOID ANALGESIC AT GLASSY CARBON ELECTRODE

Objectives: The study has been carried to investigate the electro-oxidation mechanism and to develop a selective and sensitive method for determination of ketorolac (KTL), a non-opioid analgesic drug,.Methods: A simple electro analytical method was used for the determination of ketorolac (KTL) using glassy carbon electrode by cyclic and differential pulse voltammetric techniques (DPV). The effect of various experimental parameters such as accumulation time, pH, scan rate, on the voltammetric responses of KTL was evaluated.Results: In the optimized conditions, variation of peak current with respect to concentration was studied and the calibration curve of the peak current vs. KTL concentration was drawn with a linear range of 10- 350 μM with an excellent detection limit of 8.08×10-8 M. This method was successfully tested for the determination of KTL in pharmaceuticals and human urine samples.Conclusion: From the results, it was observed that, the selected method is rapid, sensitive and low cost

DEVELOPMENT OF A SENSOR BY ELECTRO-POLYMERIZATION OF ERICHROME BLACK-T ON GLASSY CARBON ELECTRODE AND DETERMINATION OF AN ANTI-INFLAMMATORY DRUG DICLOFENAC

Objective: The aim of this study was to develop a simple, reliable voltammetric method and its validation for determination of nonsteroidal anti-inflammatory drug diclofenac (DFC). Methods: The proposed method was based on electro-oxidation of DFC at poly (erichrome black T) modified glassy carbon electrode (PEBT/GCE) in 0.2 M phosphate buffer solution of pH 7.0. Cyclic voltammetry and differential pulse voltammetric techniques were employed to study electro-oxidation behavior. Under the optimal conditions, variations of EBT concentration, effect of pH, scan rate on the oxidation of DFC was studied. Results: A well-defined oxidation peak at about +0.59 V vs. standard calomel electrode was observed for voltammetric detection of DFC. pH effect shows the participation of an equal number of protons and electrons in the mechanism. The relation between a logarithm of peak current with the logarithm of scan rate indicated adsorption controlled behavior of electrode process. Concentration variations show a good linear response in the range 0.05 µM to 40 µM with the detection limit of 5.25 × 10-8 M. Conclusion: The prepared sensor exhibited good selectivity, sensitivity, and stability for the detection of DFC in the pharmaceutical dosage form and real samples. The developed method could possibly be adopted for pharmacokinetic studies and also in clinical and quality control laboratories where time and economy were important

ELECTROCHEMICAL OXIDATION AND DETERMINATION OF AN ANTI-CANCER DRUG PEMETREXED DISODIUM

Abstract-The electrochemical oxidation of an anti-cancer drug Pemetrexed disodium has been investigated at glassy carbon electrode using voltammetric techniques. The dependence of current on potential, pH, concentrartion, scan rate, and excipients were investigated to optimize the experimental conditions. According to the liner relation between peak potential, peak current, scan rate and Pemetrexed disodium concentration, differential pulse voltammetric method for the quantitative determination in phosphate Buffer solution was developed. The linear response was obtained in the range of 10 µM to 0.75 µM with a detection limit of 0.19 µM. The electrochemical oxidation of mechanism of an anti-cancer drug Pemetrexed disodium was proposed. Keywords- Pemetrexed disodium, Cyclic Voltammetry, Electochemical Studies, Glassy carbon electrod

Oxidation of clindamycin phosphate by cerium(IV) in perchloric acid medium – A kinetic and mechanistic approach

Methyl 7-chloro-6,7,8-trideoxy-6-[(2S,4R)-1-methyl-4-propylpyrrolidine-2-carboxamido]-1-thio-1-threo-D-galactooctapyranoside monohydrochloride, commonly called clindamycin phosphate(CYN-P) used largely as an antibiotic for the treatment of serious infections caused by susceptible Gram-positive bacteria and an-aerobic bacteria was oxidized by using Ceric ammonium sulphate (Ce(IV)) in perchloric acid medium. Progress of the reaction was followed by measuring the decrease in absorbance of ceric ammonium sulphate at 360 nm. The reaction was found to be first order each in [CYN-P] and [Ce(IV)]. Order in [HClO4] was calculated as 0.8. The reactive species of Ce(IV) appears to be H3Ce(SO4)4−. Stoichiometry of the reaction was found to be 2:1 of [Ce(IV)]:[CYN-P]. Initially added product did not alter the rate of reaction. A free radical mechanism was proposed, and rate law was derived and verified. The activation parameters, ΔH≠, ΔS≠, ΔG≠ and log A were found to be 54.7 kJ mol−1, −117 J K−1 mol−1, 103 kJ mol−1 and 7, respectively

Kinetics and Mechanism of Oxidation of t-Butylbenzylamine by Diperiodatoargentate(III) in Aqueous Alkali

t-Butylbenzylamine (t-BA) is used as a free base in the synthesis of salbutamol drug. Its mechanism of oxidation was proposed from kinetic studies. The kinetics of oxidation of t-butylbenzylamine by diperiodatoargentate(III) (DPA) was studied spectrophotometrically by monitoring decrease in absorbance of DPA. The reaction was found to be first order each in [DPA] and [t-BA]. The effect of alkali concentration in a wide range on rate of reaction was studied. The rate of reaction was found to be increased with increase in [OH–] in the lower range of [OH–], decreasing effect in the middle range and at higher range again increasing effect on rate of reaction was observed. The added periodate retarded the rate of reaction. The polymerization test revealed that oxidation was occurred with the intervention free radical. A suitable mechanism was proposed for a middle range of [OH–]. The active species of silver(III) periodate for all the three different stages of [OH–] are assayed. Rate law was derived and verified. The oxidative product of t-BA was characterized by LC-ESI-MS spectra

Mechanism of Oxidation of L-Histidine by Heptavalent Manganese in Alkaline Medium

Abstract: The kinetics of oxidation of L-histidine by manganese(VII) in aqueous alkaline medium at a constant ionic strength of 0.05 mol dm -3 was studied spectrophotometrically. The reaction between permanganate and L-histidine in alkaline medium exhibits 2:1 stoichiometry (KMnO4 : L-histidine). The reaction is of first order in [KMnO4], less than unit order in [L-histidine] and [alkali]. Decrease in the dielectric constant of the medium decreases the rate of reaction. Effect of added products and ionic strength of the reaction medium have been investigated. The main products were identified by spot test and I.R. A mechanism involving the free radical has been proposed. In composite equilibrium step L-histidine binds to MnO4 -species to form a complex(C). The reaction constants involved in the different steps of mechanism are evaluated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined

Mechanism of Oxidation of L-Histidine by Heptavalent Manganese in Alkaline Medium

The kinetics of oxidation of L-histidine by manganese(VII) in aqueous alkaline medium at a constant ionic strength of 0.05 mol dm-3 was studied spectrophotometrically. The reaction between permanganate and L-histidine in alkaline medium exhibits 2:1 stoichiometry (KMnO4: L-histidine). The reaction is of first order in [KMnO4], less than unit order in [L-histidine] and [alkali]. Decrease in the dielectric constant of the medium decreases the rate of reaction. Effect of added products and ionic strength of the reaction medium have been investigated. The main products were identified by spot test and I.R. A mechanism involving the free radical has been proposed. In composite equilibrium step L-histidine binds to MnO4- species to form a complex(C). The reaction constants involved in the different steps of mechanism are evaluated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined

Silica gel-based electrochemical sensor for tinidazole

A sensitive method has been proposed for electrochemical reduction of tinidazole (TNZ) drugs employing a voltammetric approach. The supporting electrolyte, phosphate buffer solution (PBS) was prepared for different pH levels (3.0–8.0). The method involves a silica gel modified carbon paste electrode (SG/CPE) as an electrochemical sensor which demonstrated exceptional selectivity and sensitivity towards the detection of TNZ. Various parameters like the impact of accumulation time, pH of supporting buffer, scan rate, and concentration on electro-analysis of TNZ were examined. By the pH study, it was evident that the same number of protons and electrons participated in the process and by scan rate studies, we have estimated the heterogeneous rate constant and electron number. The process was irreversible and diffusion controlled. The linearity range was found to be 1.0 ​μM–10.0 ​μM from concentration variation studies. The detection and quantification limit was calculated and the practical applicability of a developed sensor is tested for tablet and urine samples. The reports obtained by studying the different parameters revealed that the electrode has good stability and sensitivity with reproducible results

Nanostructured ZnO-Based Electrochemical Sensor with Anionic Surfactant for the Electroanalysis of Trimethoprim

In this research, detection of trimethoprim (TMP) was carried out using a nanostructured zinc oxide nanoparticle-modified carbon paste electrode (ZnO/CPE) with an anionic surfactant and sodium dodecyl sulphate (SDS) with the help of voltametric techniques. The electrochemical nature of TMP was studied in 0.2 M pH 3.0 phosphate-buffer solution (PBS). The developed electrode displayed the highest peak current compared to nascent CPE. Effects of variation in different parameters, such as pH, immersion time, scan rate, and concentration, were investigated. The electrode process of TMP was irreversible and diffusion controlled with two electrons transferred. The effective concentration range (8.0 × 10−7 M–1.0 × 10−5 M) of TMP was obtained by varying the concentration with a lower limit of detection obtained to be 2.58 × 10−8 M. In addition, this approach was effectively employed in the detection of TMP in pharmaceutical dosages and samples of urine with the excellent recovery data, suggesting the potency of the developed electrode in clinical and pharmaceutical sample analysis

Sodium Dodecyl Sulfate–Mediated Graphene Sensor for Electrochemical Detection of the Antibiotic Drug: Ciprofloxacin

The present study involves detecting and determining CIP by a new electrochemical sensor based on graphene (Gr) in the presence of sodium dodecyl sulfate (SDS) employing voltammetric techniques. Surface morphology studies of the sensing material were analyzed using a scanning electron microscope (SEM) and atomic force microscope (AFM). In the electroanalysis of CIP at the developed electrode, an enhanced anodic peak response was recorded, suggesting the electro-oxidation of CIP at the electrode surface. Furthermore, we evaluated the impact of the electrolytic solution, scan rate, accumulation time, and concentration variation on the electrochemical behavior of CIP. The possible electrode mechanism was proposed based on the acquired experimental information. A concentration variation study was performed using differential pulse voltammetry (DPV) in the lower concentration range, and the fabricated electrode achieved a detection limit of 2.9 × 10−8 M. The proposed sensor detected CIP in pharmaceutical and biological samples. The findings displayed good recovery, with 93.8% for tablet analysis and 93.3% to 98.7% for urine analysis. The stability of a developed electrode was tested by inter- and intraday analysis