Dr. K Girish Kumar

Synthesis and Spectral Characterization of Lanthanide Complexes with Sulfamethoxazole and Their Antibacterial Activity

Sun, 01 Jan 2006 00:00:00 GMT

Synthesis and Spectral Characterization of Lanthanide Complexes with Sulfamethoxazole and Their Antibacterial Activity Girish Kumar, K; Karthikeyan, G; Mohanraj, K; Elango, K P A series of nonelectrolytic lanthanide(III) complexes, [ ML 2 Cl 3 ] · 2 H 2 O, where M is lanthanum(III), praseodymium(III), neodymium(III), samarium(III), gadolinium(III), terbium(III), dysprosium(III), and yttrium(III), containing sulfamethoxazole ligand (L) are prepared. The structure and bonding of the ligand are studied by elemental analysis, magnetic susceptibility measurements, IR, 1 H NMR, TG / DTA , X-ray diffraction studies, and electronic spectra of the complexes. The stereochemistry around the metal ions is a monocapped trigonal prism in which four of the coordination sites are occupied by two each from two chelating ligands, sulfonyl oxygen, and nitrogen of the amide group and the remaining three positions are occupied by three chlorines. The ligand and the new complexes were tested in vitro to evaluate their activity against the bacteria Escherichia coli and Staphylococcus aureus.

Electrochemical Reduction and Voltammetric Determination of Metronidazole Benzoate at Modified Carbon Paste Electrode

Mon, 01 Jun 2009 00:00:00 GMT

Electrochemical Reduction and Voltammetric Determination of Metronidazole Benzoate at Modified Carbon Paste Electrode Girish Kumar, K; Joseph, Renjini A metalloporphyrin incorporated carbon paste sensor has been developed for the determination of metronidazole benzoate (MTZB). Zn(II) complex of 5,10,15,20-tetrakis (3-methoxy-4-hydroxy phenyl) porphyrin (TMHPP) was used as the active material. The MTZB gave a well-defined reduction peak at - 0.713V in 0.1 mol l -1 phosphate buffer solution of pH around 7. Compared with bare carbon paste electrode (CPE), the TMHPP Zn(II) modified electrode significantly enhanced the reduction peak current of MTZB as well as lowered its reduction potential. Under optimum conditions the reduction peak current was proportional to MTZB concentration over the range 1×10-3 mol1-1 to 1×10-5mol1-1. The detection limit was found to be 4.36×10-6mol1-1 . This sensor has been successfully applied for the determination of MTZB in pharmaceutical formulations and urine samples.

Electroactive Dipyrromethene-Cu(II) Monolayers Deposited onto Gold Electrodes for Voltammetric Determination of Paracetamol

Tue, 01 Jan 2008 00:00:00 GMT

Electroactive Dipyrromethene-Cu(II) Monolayers Deposited onto Gold Electrodes for Voltammetric Determination of Paracetamol Girish Kumar, K; Grzybowska, Izabela; Orlewska, Czesława; Radecki, Jerzy; Dehaen, Wim; Radeckab, Hanna Dipyrromethene-Cu(II) derivatives possessing two dodecane alkyl chains have been used for the modification of gold electrodes. Electroactive host molecules have been incorporated into a lipophilic dodecanethiol SAM deposited onto gold electrodes through hydrophobic and van der Waals interactions (embedment technique). The presence of dipyrromethene-Cu(II) redox centers on the electrode surface was proved by cyclic voltammetry and Osteryoung square-wave voltammetry. The Au electrodes incorporating redox active Cu(II)-dipyrromethene SAMs were used for the direct voltammetric determination of paracetamol in human plasma.

Fabrication of Potentiometric Sensors for the Selective Determination of Ketoconazole

Tue, 01 Jan 2008 00:00:00 GMT

Fabrication of Potentiometric Sensors for the Selective Determination of Ketoconazole Girish Kumar, K; Augustine, Pearl; John, Sareena; Radecki, Jerzi; Radecka, Hanna 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.