Search Results

You are looking at 21 - 30 of 31 items for :

  • Author or Editor: S. Joshi x
  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

Neutron activation analysis was used to determine129I in soil and grass samples around a reprocessing plant. The method involved wet oxidation of samples, using chromic acid, followed by distillation, collection of iodine in alkaline solution, loading on Dowex-1, irradiation and post-irradiation purification steps. The -activity of130I isotope of the purified samples was measured for quantitative determination of129I. The experimental results showed that129I and the129I/127I atomic ratio in soil samples varied from 1.09×10–4 to 5.33×10–3 pCi g–1 and 0.10×10–6 to 6.12×10–6, respectively. Further, the geometric mean of soil-to-plant transfer factor (Bv) for129I was found to be 0.16 which was comparable with other published values.

Restricted access

Abstract  

Lead-210 dates are assigned to a sediment core retrieved from McKay Lake, Ottawa, Canada. Sediment mixing is found to have little, but discernible, influence on the age/depth profile. Consideration of mixing yields lower estimates of the derived ages, in agreement with the prediction based on a mathematical model. The inferred dates support the previous assignments based on Ambrosia horizon and the known occurrence of a catastrophic event. The procedures used in the calculation of the age profiles are fully described.

Restricted access

Abstract  

Thermal behavior of aqueous hydroxypropylmethylcellulose (HPMC)/surfactant mixtures was studied in the dilute concentration regime using micro-differential scanning calorimetry (DSC). The surfactant used was sodium n-dodecyl sulfate (SDS). The heat capacity of HPMC gel with various concentrations of SDS was much higher than that of the pure HPMC gel. The addition of SDS at different concentrations showed dissimilar influences on the gelation of HPMC; SDS at lower concentrations (≤6 mM) did not affect gelation temperature significantly except for enhancing the heat capacity whilst SDS at higher concentrations (≥6 mM) not only resulted in the gelation of HPMC at higher temperatures but also changed the pattern of the gelation thermograph from a single mode to a bimodal. On the basis of the observed thermal behavior of HPMC/SDS systems, the mechanism behind the sol-gel transition was discussed in terms of the properties of the surfactant and their influences on the extent of polymer/surfactant binding and polymer/polymer hydrophobic association. Gelation kinetics was analysed using the results from the DSC measurements. The kinetic parameters were determined.

Restricted access

Abstract  

High activities of radium were observed in the spring waters of Tuwa in Panchamahal district of Gujarat state. These determinations have led to further studies on geochemical behaviour of uranium in the surface sediments of this region. Labile uranium from the surface of the sediment particles is leached with saturated solution of ammonium carbonate. Uranium is chemically separated from the leachates by cellulose column chromatography. Unusually high activity ratios of234U/238U in the range of 2.3 to 2.77 were observed on the surface of the particles. The core of the particles exhibited a ratio of 1.00 indicating soluble234U fraction has migrated.

Restricted access

Abstract  

Gamma-radiolysis of KNO3 in the matrix of some sulfates, viz. Na2SO4, K2SO4, KNaSO4, KNaSO4: Eu, KNaSO4: Ce, K3Na(SO4)2, K3Na(SO4)2: Eu and K3Na(SO4)2: Ce has been studied at an absorbed dose of 30 kGy.G(NO 2 ) values calculated on the basis of electron fraction in all the sulfates are enhanced significantly. It is also affected by the nature of outer cation and the dopant lanthanide. Electron spin resonance (ESR) and thermoluminescence (TL) measurements show the formation of radical species SO 4 , SO 3 , O 3 , O 2 upon -irradiation. It is proposed that there radical species may transfer energy and interact with the radical species of nitrate (NO 3 2– , NO2, NO3 etc.) so as to enhance the decomposition. A possible mechanism has been proposed.

Restricted access

Abstract  

Cosmic ray neutron interactions with indium, used as electrical contact within a Ge diode, the diode itself and the surrounding materials can give rise to a large number of photopeaks in the 50 to 1300 keV region of background spectra of Ge spectrometers with a passive shield. The nuclear processes and decays involved in the production of these photopeaks are discussed. These cosmic ray produced photopeaks are compared with those due to primordial radionuclides. Some useful information can be drawn from these measurements on the contribution of the cosmic rays on the background of Ge detectors with a passive shield.

Restricted access

An ingredient of ‘Dasamoola’ and ‘Laghupanchamoola’ group of drugs, the source of ‘Brihati’ has been controversial. Although the dried root of Solanum anguivi is considered as the source of the drug ‘Brihati’ according to the Ayurvedic Pharmacopoeia of India, closely related and morphologically similar few species like Solanum torvum, Solanum melongena, Solanum incanum, and Solanum insanum are known as its substitutes. In the present study, a high-performance thin-layer chromatography (HPTLC) method was developed and validated for the chemoprofiling and quantitative estimation of glycoalkaloid solamargine from 5 species of the genus Solanum as well as market samples. The developed method was precise, accurate, robust, specific, and linear. The results showed that S. incanum has the highest content of solamargine, followed by S. insanum. Out of the 9 market samples analyzed, solamargine was detected only in 3 samples. Unsupervised pattern recognition techniques, such as principal component analysis and hierarchical cluster analysis, were used to analyze the complex fingerprint patterns and to predict the grouping of samples. The method clearly segregated the field and market samples. Our study is the first attempt to evaluate the drug ‘Brihati’ and the market samples using HPTLC.

Restricted access

Summary

A simple, reversed-phase HPLC method has been developed for rapid, simultaneous quantification of phenylephrine hydrochloride, guaiphenesin, ambroxol hydrochloride, and salbutamol (as salbutamol sulphate) in a commercial cough-cold liquid formulation. The compounds were separated on a 250 mm × 4.6 mm C8 column with a gradient prepared from pH 3.0 phosphate buffer and 1:1 methanol-acetonitrile as mobile phase at a flow rate of 1.0 mL min−1. Elution of the analytes was achieved in less than 15 min. Detection was by UV absorbance at 273 nm for phenylephrine hydrochloride and guaiphenesin and 225 nm for ambroxol hydrochloride and salbutamol. Percentage recovery and RSD were, respectively, 100.09% and 0.22% for phenylephrine hydrochloride, 100.43% and 0.50% for guaiphenesin, 100.91% and 0.70% for ambroxol hydrochloride, and 100.54% and 0.55% for salbutamol. The components of the syrup formulation were quantified on the basis of the peak areas obtained from freshly prepared standard solutions. The method was validated in accordance with ICH guidelines.

Open access

Summary

A simple, rapid, precise, and accurate, stability-indicating reversed phase high performance liquid chromatographic method was developed and validated for simultaneous determination of metformin HCl and repaglinide. The chromatographic separation was achieved on YMC Pack AM ODS (5 μm, 250 mm length × 4.6 mm i.d.) column at a detector wavelength of 210 nm, using an isocratic mobile phase consisting of methanol and 10 mM potassium dihydrogen phosphate buffer (pH 2.5) in a ratio of 70:30 v/v at a flow rate of 1 mL min−1. The retention times for metformin and repaglinide were found to be 2.6 and 11.3 min, respectively. The drugs were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. Validation of the method was carried out as per International Conference on Harmonization (ICH) guidelines. Linearity was established for metformin and repaglinide in the range of 5–200 μg mL−1 and 1–200 μg mL−1, respectively. The limits of detection were 0.3 μg mL−1 and 0.13 μg mL−1 for metformin and repaglinide, respectively. The method was found to be specific and stability-indicating as no interfering peaks of degradants and excipients were observed. The proposed method is hence suitable for application in quality-control laboratories for quantitative analysis of both the drugs individually and in combination, since it is simple and rapid with good accuracy and precision.

Open access
Journal of Radioanalytical and Nuclear Chemistry
Authors:
Pankaj Kumar
,
J. Pattanaik
,
S. Ojha
,
S. Gargari
,
R. Joshi
,
G. Roonwal
,
S. Balakrishnan
,
S. Chopra
, and
D. Kanjilal

Abstract  

An accelerator mass spectrometry (AMS) facility for measurements of 10Be has been developed by upgrading the 15UD Pelletron accelerator at Inter-University Accelerator Centre (IUAC), New Delhi. Details of the up gradation of the facilities and the measurement procedure are described briefly. Chemical processing for the separation of 10Be from manganese nodules and results of recent experiments on 10Be are presented.

Restricted access