Fabrication of Potentiometric Sensors for the Selective Determination of Ketoconazole

The fabrication and analytical applications of two types of potentiometric sensors for the determination of ketoconazole (KET) are described. The sensors are based on the use of KET-molybdophosphoric acid (MPA) ion pair as electroactive material. The fabricated sensors include both polymer membrane and carbon paste electrodes. Both sensors showed a linear, stable and near Nernstian slope of 57.8mV=decade and 55.2mV=decade for PVC membrane and carbon paste sensors respectively over a relatively wide range of KET concentration (1×10-2-5×10-5 and 1×10-2-1×10-6). The sensors showed a fast response time of <30 sec and <45 sec. A useful pH range of 3–6 was obtained for both types of sensors. A detection limit of 2.96 10 5M was obtained for PVC membrane sensor and 6.91 10 6M was obtained for carbon paste sensor. The proposed sensors proved to have a good selectivity for KET with respect to a large number of ions. The proposed sensors were successfully applied for the determination of KET in pharmaceutical formulations. The results obtained are in good agreement with the values obtained by the standard method.

PVC Supported Liquid Membrane and Carbon Paste Potentiometric Sensors Incorporating a Mn(III)-Porphyrin for the Direct Determination of Undissociated Paracetamol

PVC supported liquid membrane and carbon paste potentiometric sensors incorporating an Mn(III)-porphyrin complex as a neutral host molecule were developed for the determination of paracetamol. The measurements were carried out in solution at pH 5.5. Under such conditions paracetamol exists as a neutral molecule. The mechanism of molecular recognition between the Mn(III)-porphyrin and paracetamol, leading to potentiometric signal generation, is discussed.The sensitivity and selectivity toward paracetamol of carbon paste and polymeric liquid membrane electrodes incorporating an Mn(III)-porphyrin host were compared. The applicability of these sensors to the direct determination of paracetamol was checked by performing a recovery test in human plasma.

Chemically Modified Glassy Carbon Electrode as Sensors for Various Pharmaceuticals

Voltammetric methods are applicable for the determination of a wide variety of both organic and inorganic species. Its features are compact equipment, simple sample preparation, short analysis time, high accuracy and sensitivity. Voltammetry is especially suitable for laboratories in which only a few parameters have to be monitored with a moderate sample throughput. Of various electrode materials, glassy carbon electrode is particularly useful because of its high electrical conductivity, impermeability to gases, high chemical resistance, reasonable mechanical and dimensional stability and widest potential range of all carbonaceous electrodes. Electrode modification is a vigorous research area by which the electrochemical determination of various analyte species is facilitated. The scope of pharmaceutical analysis includes the analytical investigation of pure drug, drug formulations, impurities and degradation products of drugs, biological samples containing the drugs and their metabolites with the aim of obtaining data that can contribute to the maximal efficacy and maximal safety of drug therapy. This thesis presents the modification of glassy carbon electrode using metalloporphyrin and dyes and subsequently using these modified electrodes for the determination of various pharmaceuticals. The thesis consists of 9 chapters.

Effect of Carbon Black on the Mechanical and Dielectric Properties of Rubber Ferrite Composites Containing Barium Ferrite

Fine particles of barium ferrite (BaFe12O19) were synthesized by the conventional ceramic technique. These materials were then characterized by the X-ray diffraction method and incorporated in the natural rubber matrix according to a specific receipe for various loadings of ferrite. The rubber ferrite composites (RFC) thus obtained have several applications, and have the advantage of molding into complex shapes. For applications such as microwave absorbers, these composites should have an appropriate dielectric strength with the required mechanical and magnetic properties. The N330 (HAF) carbon black has been added to these RFCs for various loadings to modify the dielectric and mechanical properties. In this article we report the effect of carbon black on the mechanical and dielectric properties of these RFCs. Both the mechanical and dielectric properties can be enhanced by the addition of an appropriate amount of carbon black

Magnetic and processability studies of nitrile rubber vulcanisates containing barium ferrite and carbon black

Fine particles of barium ferrite (BaFe12O19) belonging to the M-type hexagonal ferrites were prepared by the conventional ceramic techniques. They were incorporated into a nitrile rubber matrix according to a specific recipe for various loadings to produce rubber ferrite composites (RFC). The percolation threshold is not reached for a maximum loading of 130 phr (parts per hundred rubber). Here in this paper, the magnetic properties and processability of the nitrile rubber based RFCs containing barium ferrite (BaF) and HAF carbon black is reported. The magnetic properties of the ceramic ferrite and these rubber ferrite composites were evaluated and it was found that the coercivity values of RFCs were less than that of the ceramic BaF, but remained constant with the loading of both the ferrite filler and carbon black. However, other properties like saturation magnetization and magnetic remanence increased with the loading of ferrite filler.

Carbon nanotubes induced crystallization of poly(ethylene terephthalate)

We have investigated the crystallization characteristics of melt compounded nanocomposites of poly(ethylene terephthalate) (PET) and single walled carbon nanotubes (SWNTs). Differential scanning calorimetry studies showed that SWNTs at weight fractions as low as 0.03 wt% enhance the rate of crystallization in PET, as the cooling nanocomposite melt crystallizes at a temperature 10 °C higher as compared to neat PET. Isothermal crystallization studies also revealed that SWNTs significantly accelerate the crystallization process. WAXD showed oriented crystallization of PET induced by oriented SWNTs in a randomized PET melt, indicating the role of SWNTs as nucleating sites.

Carbon Nanotubes-Reinforced PET Nanocomposite by Melt-Compounding

Poly(ethylene terephthalate) (PET) nanocomposites with single-walled carbon nanotubes (SWNTs) have been prepared by a simple melt compounding method. With increasing concentration (0-3 wt %) of SWNTs, the mechanical and dynamic mechanical properties improved, corresponding to effective reinforcement. Melt rheological characterization indicated the effective entanglements provided by SWNTs in the melt state as well. Thermogravimetric analysis suggested no influence of SWNTs on the thermal stability of PET. Electrical conductivity measurements on the composite films pointed out that the melt compounded SWNTs can result in electrical percolation albeit at concentrations exceeding 2 wt %.

Synergism of Xanthate/Dithiocarbamate Accelerator in Carbon Black Filled NR Compounds

Zinc salts of ethyl, isopropyl and butyl xanthates were prepared in the laboratory. The effect of these xanthates with zinc diethyldithiocarbamate (ZDC) on the vulcanization of HAF filled NR compound has been studied at different temperatures. The rubber compounds with the three xanthate accelerators and ZDC were cured at various temperatures from 60°C to 150°C. The sheets were moulded and properties such as tensile strength , tear strength , cross-link density, elongation -at-break, compression set, heat build up, abrasion resistance, flex resistance , etc. were evaluated . The properties showed that zinc xanthate/ZDC accelerator combination has a positive synergistic effect on the mechanical properties of NR compounds. The curing of HAF filled NR compound containing zinc xanthate /ZDC is slightly slower than the curing of the corresponding gum compounds . It is observed that, by gradually increasing the amount of the accelerator, the cure time of black filled NR compound can be made equal to that of the gum compou

Studies on Latex Stage Carbon Black Masterbatching of NR and its Blend with SBR

Carbon Black is incorporated In natural rubber latex in , the presence of polyethylene glycol. The dispersion of carbon blade in the vulcanizatea is analyzed using polaroid M.4 land camera The mechanical properties of the carbon black meeterbatched NR/SBR blend Is compared with that of conventional NR/SBR blend before and after ageing , The resilience, flex resistance and hardness are found to be superior for N-LCMISBR compounds. The compression set and abrasion resistance are comparable for both types of blends . The processebiity and die swell of these blends at different shear rates are also compared.

Studies on Magnetic Iron Oxide Loaded Activated Carbon

The current water treatment technology is oriented towards the removal of contaminants, mostly organic compounds, by activated carbon. Activated carbons are classified as Granular Activated Carbons (GAC) and Powdered Activated Carbons (PAC) on the basis of the particle size of the carbon granules. Powdered carbons are generally less expensive than granular carbon, operating costs with powdered carbon could be lower. Though powdered activated carbon has many advantages over granular carbon, its application in large-scale separation process is limited by difficulty in recovery and regeneration. Deposition of magnetic iron oxide on carbon particles provides a convenient way of recovering the spent carbon from process water. The study deals with the preparation and physico-chemical characterization of magnetic iron oxide loaded activated carbons. The evaluation of absorption properties of magnetic iron oxide loaded activated carbon composites. The target molecules studied were phenol, p-nitro phenol and methylene blue. The feasibility of magnetic separation of iron oxide loaded activated carbons were studied and described in this thesis.

Microwave Absorbing Material Using Rubber & Carbon

Development of a new type of microwave absorbing material using rubber latex and carbon. for application in the interior lining of anechoic chambers, has been reported. Absorption coefficients of different combinations were estimated at X and S bands and the results were presented graphically. A combination of 50% rubber latex, 40% carbon and 10% graphite is found to form an ideal microwave absorbing material in the X and s bands

Dielectric Properties of Ba5Nb4O15 Ceramic

Ceramic dielectrics with high dielectric constant in the microwave frequency range are used as filters, oscillators [I], etc. in microwave integrated circuits (MICs) particularly in modern communication systems like cellular telephones and satellite communications. Such ceramics, known as 'dielectric resonators (DRs),donot only offer miniaturisation and reduce the weight of the microwave components. but also improve the efficiency of MICs

Microwave Characterisation of BaCe2Ti5O15 and Ba5Nb4O15 Ceramic Dielectric Resonators Using Whispering Gallery Mode Method

A microwave dielectric ceramic resonator based on BaCe2Ti5O15 and Ba5Nb4O15 have been prepared by conventional solid state ceramic route. The dielectric resonators (DRs) have high dielectric constant 32 and 40 for BaCe2Ti5O15 and Ba5Nb4O15, respectively. The whispering gallery mode (WGM) technique was employed for the accurate determination of the dielectric properties in the microwave frequency range. The BaCe2Ti5O15 and Ba5Nb4O15 have quality factors (Q X F) of 30,600 and 53,000 respectively. The quality factor is found to depend on the azimuthal mode numbers. The temperature coefficient of resonant frequency (Tr) of BaCe2Ti5O15 and Ba5Nb4O15 have been measured accurately using different resonant modes and are + 41 and + 78 ppm/K, respectively

Ba(Tb1/2Nb1/2)03: A New Ceramic Microwave Dielectric Resonator

A new microwave dielectric resonator Ba(Tb1/2Nb1/2)03 has been prepared and characterized in the microwave frequency region. 1 wt% CeO2 is used as additive to reduce the sintering temperature. The sintered samples were characterized by XRD, SEM and Raman spectroscopic methods. Microwave DR properties such as er, Q factor and temperature-coefficient of resonant frequency (Ti) have been measured using a HP 8510 B Network Analyzer. Cylindrical DRs of Ba(Tb1/2Nbi/2)03 showed high Er (~ 37), high Q (~3,200) and low Tf (~10 ppm /°C) at 4 GHz and hence are useful for practical applications