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Abstract  

We describe a radioimmunoassay procedure for human somatotropin using second antibody — polyethylene glycol (PEG) combination for the separation of antibody bound and free antigen. The assay is done by a single incubation of 18 hours or with one hour pre-incubation and 3 hours post-incubation at room temperature (25 °C) and uses 0.1 m of serum sample. The assay covers a range of 0–40 g/ and has a sensitivity of 0.6 g/ of somatotropin. The assay is validated by inter-assay and intra-assay variations, recovery and parallelism tests.

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Abstract  

We discribe the development of a simplified radioimmunoassay for triiodothyronine (T3) using pre-incubated labelled T3 and antibody. The assay is carried out by adding 50 l of standard or sample to 0.4 ml of pre-incubated reagent dispensed in assay tubes. The reaction is allowed to proceed for about four hours and the antigen-antibody complex precipitated by the addition of 1 cm3 of 22% polyethylene glycol solution. Due to the high dissociation constant of T3-antibody complex at 37° C (2.83·10–4 S–1), the labelled antigen-antibody complex dissociates and thereby the unlabelled antigen binds with the antibody. With a four hour incubation the sensitivity of this assay is comparable to an assay done by the equilibrium method using the same antibody. Sixty serum samples were analyzed using this method and compared with the equilibrium assay (Y=0.94x+0.046 ng/cm3, r=0.98).

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Abstract  

Chitosan tripolyphosphate (CTPP) beads were prepared at two different cross-linking densities and adsorption of Cr(III) onto it were studied as a function of different operational parameters such as solution pH, equilibration time and initial Cr(III) ion concentration. Higher cross-linked beads were found to have more adsorption capacity at all the experimental pH employed (pH = 3–5), whereas adsorption capacity is found to increase with increase in pH. Adsorption data were analyzed using Langmuir and Freundlich isotherm models. Langmuir model is found be more suitable to explain the experimental results with a monolayer adsorption capacity of 469.5 mg/g. Among the kinetic models used, pseudo-second order kinetic model could best describe the adsorption process. Competition experiments done in presence of Na(I), Mg(II), Ca(II), Al(III) and Fe(III) revealed that, except in the case of Al(III), adsorption of Cr(III) is not significantly affected by the presence of foreign cations. NaCl is found to be a suitable leaching agent for the desorption of adsorbed Cr(III) from CTPP beads. FTIR spectroscopic investigations confirmed that phosphate groups are the principal binding site responsible for the sorption of Cr(III) onto CTPP beads.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Debasish Das, M. Sureshkumar, Siddhartha Koley, Nidhi Mithal, and C. Pillai

Abstract  

Magnetite (Fe3O4) nanoparticle was synthesized using a solid state mechanochemical method and used for studying the sorption of uranium(VI) from aqueous solution onto the nanomaterial. The synthesized product is characterized using SEM, XRD and XPS. The particles were found to be largely agglomerated. XPS analysis showed that Fe(II)/Fe(III) ratio of the product is 0.58. Sorption of uranium on the synthesized nanomaterials was studied as a function of various operational parameters such as pH, initial metal ion concentration, ionic strength and contact time. pH studies showed that uranium sorption on magnetite is maximum in neutral solution. Uranium sorption onto magnetite showed two step kinetics, an initial fast sorption completing in 4–6 h followed by a slow uptake extending to several days. XPS analysis of the nanoparticle after sorption of uranium showed presence of the reduced species U(IV) on the nanoparticle surface. Fe(II)/Fe(III) ratio of the nanoparticle after uranium sorption was found to be 0.48, lower than the initial value indicating that some of the ferrous ion might be oxidized in the presence of uranium(VI). Uranium sorption studies were also conducted with effluent from ammonium diuranate precipitation process having a uranium concentration of about 4 ppm. 42% removal was observed during 6 h of equilibration.

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Abstract  

A simple and reliable technique for the simultaneous estimation of serum triiodothyronine (T3) and thyroxine (T4) is discussed. T3 assay was done by the solid phase technique using antibody coated Eppendorf pipette tips. T4 assay was done by the polyethylene glycol separation system. The assay used 50 l of serum sample. Inter-assay and intra-assay coefficient of variation are less than 12% throughout the assay range, for both assays.

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