Electrochemical Stripping Studies of Amlodipine Using Mwcnt Modified Glassy Carbon Electrode

The voltammetric behaviour of amlodipine was studied on multiwall carbon nanotubes (MWCNT) modified glassy carbon electrode. The oxidation of amlodipine is irreversible and exhibits a diffusion controlled process which is pH dependent. The oxidation mechanism was proposed in this work. The dependence of the current on pH, the concentration and nature of buffer, and scan rate were investigated to optimize the experimental conditions for the determination of amlodipine. Calibration plots were drawn between stripping peak current and concentration. They are linear within the range from 0.01 to 0.3 µg/mL. The lower limit of detection (LOD) was found to be very low (0.001 µg/mL) on MWCNT. The developed MWCNT modified glassy carbon electrode system was applied to successfully determine amlodipine in commercial pharmaceutical products. Key Words: Voltammetric, Multiwall Carbon Nanotubes, Amlodipine, Stripping

5-[1-(4-Meth­oxy­phen­yl)-2-nitro­but­yl]-4-phenyl-1,2,3-selenadiazole

In the title compound, C19H19N3O3Se, the selenadiazole ring is essentially planar (r.m.s. deviation = 0.001 Å). The heterocyclic ring makes dihedral angles of 50.2 (2) and 76.3 (9)°, respectively, with the meth­oxy­phenyl and phenyl rings

5-(2-Nitro-1-phenyl­but­yl)-4-phenyl-1,2,3-selenadiazole

In the title compound, C18H17N3O2Se, the selenadiazole ring is planar [maximum deviation = 0.012 (2) Å for the ring C atom bearing the phenyl substituent]. The dihedral angle between the selenadiazole ring and the attached benzene ring is 46.5 (1)°. There is one short intra­molecular C—H⋯Se contact

Utilization of sodium montmorillonite clay for enhanced electrochemical sensing of amlodipine

Nanosize surface of sodium montmorillonite has been prepared via sonication and deposited on glassy carbon electrodes for use as working electrode in a highly sensitive electrochemical biosensor for the detection of trace amounts of the calcium channel blocking drug, amlodipine. The cyclic voltammetric behaviour of amlodipine is studied in the pH range of 1.0−13.0. In alkali medium (pH 13.0) the sensor shows good response. Cyclic voltammograms show one oxidation peak and one broad reduction peak, which may be due to the oxidation of secondary amino group and reduction of chlorine and nitro groups respectively. Plots of log peak current and potential when correlated with log scan rate, indicate irreversible electron diffusion controlled redox reaction. The optimum conditions have been established by differential pulse stripping voltammetry. The anodic peak current is linear with concentration of the analyte at optimum conditions; the detection limit has been determined to be 0.01 mg/mL. A simple, sensitive and time-saving differential pulse stripping voltammetric procedure has been developed for estimation of amlodipine in its formulations as tablets

1-(2-Naphth­yl)-3-phenyl-3-(4,5,6,7-tetra­hydro-1,2,3-benzoselenadiazol-4-yl)propan-1-one

In the title compound, C25H22N2OSe, the fused six-membered cyclo­hexene ring of the 4,5,6,7-tetra­hydro-1,2,3-benzoselenadiazole group adopts a near half-chair conformation and the five-membered 1,2,3-selenadiazole ring is essentially planar (r.m.s. deviation = 0.004 Å). There are weak inter­molecular C—H⋯O and C—H⋯π inter­actions in the crystal structure. Inter­molecular π–π stacking is also observed between the naphthyl units, with a centroid–centroid distance of 3.529 (15) Å

Ethyl 2-phenyl-3-(4-phenyl-1,2,3-selenadiazol-5-yl)-3-p-tolyl­propano­ate

In the title compound, C26H24N2O2Se, the selenadiazole ring is essentially planar [maximum deviation = 0.004 (3) Å]. The dihedral angle between the selenadiazole ring and the attached benzene ring is 50.17 (1)°. The crystal packing is stabilized by inter­molecular C—H⋯N inter­actions

4-{(4-Chloro­phen­yl)[4-(4-methyl­phen­yl)-1,2,3-selenadiazol-5-yl]meth­yl}-4,5,6,7-tetra­hydro-1,2,3-benzoselenadiazole

In the title compound, C22H19ClN4Se2, the mean plane of the non-fused selenadiazole ring forms dihedral angles of 54.20 (16)° and 70.48 (11)°, respectively, with the essentially planar [maximum deviations of 0.025 (5) and 0.009 (2) Å, respectively] methyl­phenyl and chloro­phenyl substituents. The tetra­hydro-1,2,3-benzoselenadiazole group is disordered over two sets of sites with a refined occupancy ratio of 0.802 (5):0.198 (5). In the crystal, weak inter­molecular C—H⋯N inter­actions are observed

3-(4-Methyl­phen­yl)-1-phenyl-3-(4,5,6,7-tetra­hydro-1,2,3-benzoselenadiazol-4-yl)propan-1-one

In the title compound, C22H22N2OSe, the fused six-membered ring of the 4,5,6,7-tetra­hydro­benzo[d][1,2,3] selenadiazole group adopts a near to envelope (E form) conformation and the five-membered 1,2,3-selenadiazole ring is essentially planar (r.m.s. deviation = 0.0059 Å). In the crystal, adjacent mol­ecules are inter­linked through weak inter­molecular C—H⋯π inter­actions

Study of Shock-Wave Boundary-Layer Interaction Control Using an Array of Steady Micro-Jet Actuators

An experimental investigation was conducted to control the amplitude of shock unsteadiness associated with the interaction induced by a (i) 24o compression corner and, (ii) a cylindrical obstruction on a flat plate in a Mach 2 flow. The control was applied in the form of an array of steady micro air-jets of different configurations with variation in pitch angle (β) and skew angle (α) of the jets. The overall flow interaction gets modified for all control configurations and shows a reduction in both separation- and bow-shock strengths and in triple-point height. A significant reduction in σmax /Pw value is also observed in the intermittent region of separation for each case. On the other hand, pitching or skewing the jets to 45o or both reduces the obstruction component considerably that initially, at lower control pressure, shows lower effectiveness (relative to 90o pitched jets). But at higher control pressure, the effectiveness of these configurations continues to increase unlike the 90o pitched jets