The thermal behavior of chitosan (CS)/natural rubber latex (NRL) blends has been studied by thermogravimetry (TG) and differential
scanning calorimetry (DSC). Decomposition behavior of CS changes with the addition of NRL. The effect of blend composition
on the amount of residue remaining at various temperatures has been studied. Activation energies of degradation have been
calculated using Horowitz-Metzger equation. From the activation energy values, it is found that among the series of the blend
compositions, CS15NRL85 exhibits better thermal stability. DSC studies reveals that the CS/NRL blends are thermodynamically incompatible. This is
evident from the presence of two glass transitions, corresponding to CS and NRL phases in the blend.
A new method for the continuous determination of H2O2 is described based on the catalytic decomposition of H2O2 by LaCoO3. Oxygen liberated is measured by a gas meauuring burette. -irradiated catalyst enhances the catalytic activity and decreases the time required for complete decomposition. The procedure is suitable for microdetermination of H2O2 in various food products.
Chemisorbed oxygen can be determined quantitatively by the measurement of gaseous N2/N2O liberated by treatment with hydrazine sulphate/hydroxylamine hydrochloride. The amount of chemisorbed oxygen depends on the degree of dispersion during irradiation and also the -dose. The chemisorption is enhanced in the presence of moisture. The partial reduction of the transition metal ion favours the formation of chemisorbed oxygen.
Bioassay technique is used for the estimation of actinides present in the body based on their excretion rate through body
fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure.
Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by
alpha spectrometry requires pre-concentration of large volumes of urine. This article deals with standardization of analytical
method for the determination of 241Am isotope in urine samples using Extraction Chromatography (EC) and 243Am tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of americium along
with calcium phosphate. This precipitate after treatment is further subjected to calcium oxalate co-precipitation. Separation
of Am was carried out by EC column prepared by PC88-A (2-ethyl hexyl phosphonic acid 2-ethyl hexyl monoester) adsorbed on
microporous resin XAD-7 (PC88A-XAD7). Am-fraction was electro-deposited and activity estimated using tracer recovery by alpha
spectrometer. Ten routine urine samples of radiation workers were analyzed and consistent radiochemical recovery was obtained
in the range 44–60% with a mean and standard deviation of 51 and 4.7% respectively.
is an important medicinal plant widely used in the Unani system of medicine. A simple, precise and convenient HPTLC method has been developed for analysis of chrysophanol, an antioxidant and a major constituent of the rhizomes of
(Polygonacea) and pharmaceutical formulations of these. This method uses chrysophanol as internal standard. The stationary phase was silica gel 60F
, and hexane-ethyl acetate, 45 + 5 (
) was used as mobile phase. Detection and quantification were performed densitometrically at
= 366 nm. The method is characterized by high sensitivity and linearity over a wide concentration range. The results obtained were evaluated statistically.
Ammonium molybdophosphate (AMP) was irradiated with electrons up to a dose of 1 MGy. X-ray diffraction patterns and FT-IR of irradiated and control AMP samples were recorded. Uptake of137Cs from nitric acid in the range of 0.2 to 10 mol·dm–3 was estimated by a batch equilibration technique. AMP undergoes perceptible changes in its physico-chemical characteristics on irradiation with electrons. Uptake of137Cs from nitric acid by irradiated AMP was nearly the same as the control AMP in the nitric acid concentration range of 6 to 10 mol·dm–3 and relatively higher in the range of 0.2 to 6 mol·dm–3. The results are discussed in terms of available information on the physicochemical properties of 12-heteropoly acids and their salts.
Authors:P. Gopi Krishna, J. M. Gladis, K. S. Rao, T. Prasada Rao, and G. R. K. Naidu
A new chelating solid extractant prepared by the chemical immobilization of xanthate on silica gel was characterized by Fourier
transform infra red spectrometry (FTIR), thermogravimetric analysis (TGA) and microanalysis and used for the preconcentration
and separation of uranyl ion prior to its determination by Arsenazo-III. The effect of pH, weight of the solid extractant,
volume of the aqueous phase and the interference of neutral electrolytes, cations and anions on the determination of uranium,
have been studied in detail to optimize the conditions for trace determination of uranium(VI). The accuracy of the developed
procedure was tested by analyzing marine sediment (MESS-3) and soil (IAEA-SOIL-7) reference materials. The results obtained
on analysis of soil and sediment samples are comparable to standard ICP-MS values.
Authors:S. Balasubrahmanyam, B. Viswanathan, V. Rao, and J. Kuriacose
The effect of60Co -radiation on La2CuO4 solid catalyst prepared by the ceramic method has been studied. Gamma irradiation of La2CuO4 samples has been found to increase the Cu+ content, electrical conductivities and decrease the magnetic susceptibilities of the catalyst. The results have been interpreted on the basis of the crystal field model of the structure of La2CuO4.