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Search Results: 1 - 10 of 144683 matches for " B. Narayana "
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A simple method for the spectrophotometric determination of cephalosporins in pharmaceuticals using variamine blue
Pasha, C.;Narayana, B.;
Eclética Química , 2008, DOI: 10.1590/S0100-46702008000200006
Abstract: a simple spectrophotometric method for the determination of cefotaxime, ceftriaxone, cefadroxil and cephalexin with variamine blue is presented. the determination is based on the hydrolysis of β-lactam ring of cephalosporins with sodium hydroxide which subsequently reacts with iodate to liberate iodine in acidic medium. the liberated iodine oxidizes variamine blue to violet colored species of maximum absorption at 556 nm. the absorbance is measured within the ph range of 4.0-4.2. beer's law is obeyed in the range of 0.5-5.8 μg ml-1, 0.2-7.0 μg ml-1, 0.2-5.0 μg ml-1 and 0.5-8.5 μg ml-1 for cefotaxime, ceftriaxone, cefadroxil and cephalexin respectively. the analytical parameters were optimized and the method is successfully applied for the determination of cefotaxime, ceftriaxone, cefadroxil and cephalexin in pharmaceuticals.
A facile spectrophotometric method for the determination of hypochlorite using rhodamine B
Pasha, Chand;Narayana, B.;
Journal of the Brazilian Chemical Society , 2007, DOI: 10.1590/S0103-50532007000100018
Abstract: a simple, rapid and sensitive spectrophotometric method has been developed for the determination of hypochlorite using rhodamine b. the proposed method reports the reaction of hypochlorite with potassium iodide in an acid medium with iodine liberation. the liberated iodine bleaches the pinkish red color of the rhodamine b and can be measured at 553 nm. this decrease in absorbance is directly proportional to the hypochlorite concentration and obeys beer's law in the range of 0.1 - 4.0 μg ml-1of hypochlorite. the molar absorptivity, sandell's sensitivity, detection limit and quantitation limit of the method were found to be 2.57×105 l mol-1 cm-1, 2.01×10-3 μg cm-2, 0.070 μg ml-1 and 0.212 μg ml-1 respectively. the optimum reaction conditions and other analytical parameters were evaluated. the effect of interfering ions on the determination is described. the proposed method has been successfully applied to the determination of the hypochlorite in various samples of tap water, natural water and milk.
Rapid spectrophotometric determination of trace amounts of chromium using variamine blue as a chromogenic reagent
Narayana, B.;Cherian, Tom;
Journal of the Brazilian Chemical Society , 2005, DOI: 10.1590/S0103-50532005000200011
Abstract: a simple, rapid and sensitive spectrophotometric method has been developed for the determination of trace amounts of chromium using variamine blue as a chromogenic reagent. the proposed method is based on the reaction of chromium(vi) with potassium iodide in acid medium to liberate iodine, which oxidizes variamine blue to form a violet colored species having an absorption maximum 556 nm. beer's law is obeyed in the range 2-12 mg ml-1 of cr(vi). the molar absorptivity, sandell's sensitivity, detection limit and quantitation limit of the method were found to be 0.911×104 l mol-1 cm-1, 1.14×10-2 mg cm-2, 0.02 mg ml-1 and 0.07 mg ml-1 respectively. the optimum reaction conditions and other analytical conditions were evaluated. the effect of interfering ions on the determination is described. the chromium(iii) can be determined after it is oxidized with bromine water in alkaline medium to chromium(vi). the developed method has been successfully applied to the analysis of the chromium in alloy steels, industrial effluents, natural water samples and soil samples.
A facile spectrophotometric method for the determination of periodate using azure B
Narayana, B.;Cherian, Tom;
Journal of the Brazilian Chemical Society , 2005, DOI: 10.1590/S0103-50532005000600014
Abstract: a simple, rapid and sensitive spectrophotometric method has been developed for the determination of periodate in solution and river water samples. the method is based on the reaction of periodate with iodide in an acid medium to liberate iodine. this liberated iodine bleaches the violet color of the azure b and is measured at 644 nm. this decrease in absorbance is directly proportional to the periodate concentration and obeys beer's law in the range of 0.2 - 5.5 μg ml-1. the molar absorptivity, sandell's sensitivity, detection limit and quantitation limit of the method were found to be 1.09 x 105 l mol-1 cm-1 , 1.75 x10-3 μg cm-2, 0.07 μg ml-1 and 0.20 μg ml-1 respectively. the optimum reaction conditions and other analytical parameters were evaluated. the effect of interfering ions on the determination is described. the proposed method has been successfully applied to the determination of periodate in solutions and river water samples.
A SIMPLE SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF VANADIUM USING THIONIN
Tom Cherian, B. Narayana*
Bulletin of the Chemical Society of Ethiopia , 2005,
Abstract: A simple and sensitive spectrophotometric method has been developed for the determination of trace amounts of vanadium using thionin as a chromogenic reagent. The proposed method is based on the reaction of vanadium(V) with potassium iodide in acid medium to liberate iodine, which bleaches the violet colour of thionin and is measured at 600 nm. This decrease in absorbance is directly proportional to the vanadium(V) concentration and obeys Beer\'s law in the range of 0.2-10 μgmL-1 of V(V). The molar absorptivity, Sandell\'s sensitivity, detection limit and quantitation limit of the method were found to be 2.298 x 104 Lmol-1cm-1, 0.52 x 10-2 μgcm-2, 0.035 μgmL-1 and 0.11 μgmL-1, respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination is described. The developed method has been successfully applied to the analysis of the vanadium in synthetic and alloy samples. KEY WORDS: Vanadium determination, Spectrophotometry, Thionin Bull. Chem. Soc. Ethiop. 2005, 19(2), 155-161
Monilethrix
Sathya Narayana B
Indian Journal of Dermatology, Venereology and Leprology , 1998,
Abstract:
A simple spectrophotometric determination of trace amounts of vanadium using thionin
Tom Cherian,B. Narayana
Bulletin of the Chemical Society of Ethiopia , 2005,
Abstract: A simple and sensitive spectrophotometric method has been developed for the determination of trace amounts of vanadium using thionin as a chromogenic reagent. The proposed method is based on the reaction of vanadium(V) with potassium iodide in acid medium to liberate iodine, which bleaches the violet colour of thionin and is measured at 600 nm. This decrease in absorbance is directly proportional to the vanadium(V) concentration and obeys Beer's law in the range of 0.2-10 μgmL-1 of V(V). The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit of the method were found to be 2.298 x 104 Lmol-1cm-1, 0.52 x 10-2 μgcm-2, 0.035 μgmL-1 and 0.11 μgmL-1, respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination is described. The developed method has been successfully applied to the analysis of the vanadium in synthetic and alloy samples.
Spectrophotometric determination of nevirapine using tetrathiocyanatocobalt(II) ion as a reagent
Sreevidya, T. V;Narayana, B;
Eclética Química , 2010, DOI: 10.1590/S0100-46702010000300008
Abstract: a simple and rapid spectrophotometric method for the determination of nevirapine is described. the method is based on the reaction of nevirapine with tetrathiocyanatocobalt(ii) ion in buffer of ph 4 to form the corresponding complex. beer's law is obeyed in the range of 0.2 - 2.0 μg ml-1 for nevirapine. the optical parameters such as molar absorptivity, sandell's sensitivity, detection limit and quantitation limit were found to be 1.16× 104 lmol-1cm-1, 2.09 x 10-3 μg cm-2, 0.073 μg ml-1 and 0.222 μg ml-1 respectively. the optimum reaction conditions and other analytical parameters were evaluated. the statistical evaluation of the method was examined by determining intra-day and inter-day precision. the proposed method has been successfully applied for the determination of nevirapine in pharmaceutical formulations.
Simple Methods for the Spectrophotometric Determination of Carvedilol
Divya N. Shetty,B. Narayana
ISRN Spectroscopy , 2012, DOI: 10.5402/2012/373215
Abstract: Two simple spectrophotometric methods are described for the determination of carvedilol (CAR). Method A is the condensation reaction of CAR with p-dimethylaminobenzaldehyde (PDAB), and the reaction mixture exhibits maximum absorbance at 601?nm. Method B is based on the charge transfer complex formation of CAR with p-chloranil; the color developed is measured at 662?nm. The calibration graphs are found to be linear over 50.00–250.00 and 20.00–100.0?μg mL?1 with molar absorptivity values of and ?L mol?1cm?1 for CAR-PDAB and CAR-p-chloranil, respectively. Statistical comparisons of the results are performed with regard to accuracy and precision using Student’s t-test and F-test at 95% confidence level. The methods are successfully employed for the determination of CAR in pharmaceutical preparations, and the results agree favorably with the reference and proposed methods. 1. Introduction Carvedilol (1-(9H-carbazol-4-yloxy)-3-[2-(2-methoxyphenoxy)ethylamino]propan-2-ol) belongs to a group of medicines called beta-adrenergic blocking agents, that are indicated for the treatment of hypertension, angina pectoris, and heart failure. Beta-blockers work by affecting the response to some nerve impulses in certain parts of the body. As a result, they decrease the heart’s need for blood and oxygen by reducing its workload. They also help the heart to beat more regularly. CAR is used for treating high blood pressure and congestive heart failure. By blocking the receptors, CAR reduces the heart’s rate and force of contraction and thereby reduces the work of the heart. CAR also blocks adrenergic receptors on arteries and causes the arteries to relax and the blood pressure to fall. The drop in blood pressure further reduces the work of the heart since it is easier to pump blood against a lower pressure. The FDA first approved CAR in 1995 [1]. Many methods have been used for the determination of carvedilol such as HPLC [2–7], capillary electrophoresis [8], fluorometry [9], and differential pulse voltammetry [10]. Recently a second polymorph of carvedilol has also been reported [11]. The two spectrophotometric methods [12, 13] reported earlier for the determination of CAR are in the UV region, and it is well known that UV-spectrophotometry is not a selective method, and therefore excipients can interfere with the method. The other three methods [14, 15] involve reaction of CAR with reagents like bromocresol green, ninhydrin, acetaldehyde, and nitroprusside. A comparison of the performance characteristics of the reported methods and proposed methods is given in Table 1.
(E)-3-(4-Bromophenyl)-1-(3,4-dichlorophenyl)prop-2-en-1-one
Rajni Kant,Kamni,B. Narayana,K. Veena
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809008162
Abstract: The molecule of the title compound, C15H9BrCl2O, is shown to be the E isomer, with the 3,4-dichlorobenzoyl and p-bromophenyl substituents in trans positions with respect to the chalcone olefin bond. The molecule is non-planar, the two aromatic rings forming a dihedral angle of 49.58 (1)°.
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