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Abstract  

Correlations have been established between %Eff 240Pu and various plutonium isotopes formed in thermal reactors. Based on these correlations, a method has been developed for the estimation of isotopic composition of plutonium obtained from thermal reactors. The method is simple, fast, non-destructive and finds application for the verification of plutonium isotopic composition in the finished products of known plutonium content. The method could be applied in the nuclear fuel fabrication to verify and confirm the fissile content (239Pu+241Pu) specification. It has also been shown that in principle, similar correlations could be established for Pu obtained from different thermal reactor fuels with reactor specific fitting parameters.

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Abstract  

Twenty-two trace elements have been measured by INAA in materials produced in the Solvent Refined Coal (SRC) pilot plant. The elements As, Sb, Se, Hg, Ni, Br, Na, K, Cr, Sc, Fe, Co, Cs, Ce, Rb, Th, Sr, Ba, Tb, Eu, Sm and Lu were measured in coal, SRC, insoluble residues, solvents, and process waters. The liquefaction process produces a fuel lower in toxic trace elements than the parent coal. Elemental balances indicate that except for As, and Hg the SRC and insoluble residues contain more than 80% of the trace elements found in the coal. Evidence is presented indicating significant organic binding of As, Se, Hg, Br, Ni, and Co in the SRC.

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Determination of trace elements in petroleum by neutron activation analysis

I. Determination of Na, S, Cl, K, Ca, V, Mn, Cu, Ga and Br

Journal of Radioanalytical and Nuclear Chemistry
Authors:
K. Shah
,
R. Filby
, and
W. Haller

Abstract  

Using thermal neutron activation and a large-volume high-resolution Ge(Li) γ-ray spectrometer, the feasibility of the determination of the concentrations of Na, S, Cl, K, Ca, V, Mn, Cu, Ga, and Br in crude oils has been demonstrated. This instrumental method, which requires neither a chemical separation technique nor pre-concentration or post-concentration of trace elements by ashing, eliminates many inherent errors associated with chemical determination. The method is sensitive, precise and suitable for routine analysis. Fast neutron (n, p) and (n, α) reactions do not appreciably interfere and where necessary corrections may be applied. Loss of volatile elements, e.g. chlorine and bromine, due to recoil during irradiation is negligible.

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Determination of trace elements in petroleum by neutron activation analysis

II. Determination of Sc, Cr, Fe, Co, Ni, Zn, As, Se, Sb, Eu, Au, Hg and U

Journal of Radioanalytical and Nuclear Chemistry
Authors:
K. Shah
,
R. Filby
, and
W. Haller

Abstract  

Instrumental neutron activation analysis (INAA) and Ge(Li) spectrometry have been used to determine Sc, Cr, Fe, Co, Ni, Zn, As, Se, Sb, Eu, Au, Hg, and U in crude petroleum. The technique involves no chemical separations and no pre-concentration of the samples by ashing is necessary, thus avoiding contamination or loss of volatile elements. The estimated detection limits in ppb for the elements are Sc (0.1), Cr (0.16), Fe (400.0), Co (0.6), Ni (1.1), Zn (200.0), As (6.0), Se (23.0), Sb (1.0), Eu (0.58), Au (0.11), Hg (4.3), U (1.5). Precision values ranged from 0.1% to 15% (relative standard deviation). Interferences in the Co and Fe determinations due to fast neutron reactions (n, p) and (n, α) on Ni isotopes are small and are easily corrected. Losses of As, Se, and Hg due to escape of volatile gases during irradiation are negligible

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Abstract  

A rapid and sensitive radioimmunoassay has been developed for the measurement of Human Chorionic Gonadotropin (HCG) in serum. Human chorionic gonadotropin has been labelled with125I to attain a specific activity between 80–120 μCi/μg. Aqueous dioxane (74 vol. %) has been employed to separate the bound and freehormone in the radioimmunoassay. The sensitivity of this technique has been found to be ∼1.5 mIU/ml of HCG. The intra assay variation has been found to be less than 5% and inter assay variation has been found to be less than 12%.

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Abstract  

Neutron activation analysis and Ge(Li) spectroscopy was used to determine 32 elements in seven U.S.G.S. standard rocks of a wide range of composition. Short half-life nuclides (10 sec-10 min) were used to measure Sc, Hf, Dy, Mg, Al, Ca, Ti, V (and Na) in an automated rabbit Ge(Li) detector system. The elements K, Cu, Zn, Ga, Sr, Ba, La, Eu, Sm (and Mn) were determined by dissolution of the irradiated sample followed by removal of24Na on hydrated antimony pentoxide (HAP). Long-lived nuclides were used to measure Sc, Cr, Fe, Co, Zr, Rb, Sb, Cs, Ba, Ce, Eu, Yb, Tb, Lu, Hf, Ta and Th after decay of24Na. The method involves little radiochemistry and the separation is selective for24Na under the experimental conditions used. Elemental concentrations determined agree well with previously published data.

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Summary

In the present study, a design of experiment (DoE) approach was used to optimize chromatographic conditions for the development of a high-performance thin-layer chromatography (HPTLC) method for the simultaneous estimation of metformin hydrochloride (MET) and ursodeoxycholic acid (URSO) in pharmaceutical dosage form. The critical factors were identified using a Taguchi design, and after identification of critical factors, optimization was done using Box-Behnken design (BBD). BBD was used to optimize the compositional parameters and to evaluate the main effect, interaction effects, and quadratic effects of the mobile phase compositions, development distance, and saturation time on the retardation factor (R F) of both drugs. HPTLC separation was performed on aluminum plates pre-coated with silica gel 60 F254 as the stationary phase, using toluene–ethanol–acetone–formic acid (4.5:2:2.5:0.85, V/V) as the mobile phase at a wavelength of 234 nm and 700 nm for MET and URSO, respectively. A sharp and well-resolved peak was obtained for MET and URSO at R F values of 0.19 and 0.80 min, respectively. The calibration curve was in the range of 5000–40000 ng per spot and 1500–12000 ng per spot for MET and URSO, with r 2 = 0.984 and r 2 = 0.980, respectively. The method was validated for linearity, accuracy, precision, limit of detection, limit of quantification, and specificity. To provide a better visualization of the statistically significant factors derived from the statistical analysis, the perturbation plot and response surface plot for the effect of independent variables on the R F of MET and URSO were evaluated. Stability study was performed under different stress conditions such as acid and alkali hydrolysis, oxidation, and temperature. The developed method was able to resolve drugs and their degradation products formed under the afore-mentioned conditions.

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Abstract  

A sensitive and specific radioimmunossay procedure (RIA) has been developed for the measurement of Human Placental Lactogen (HPL). Pure HPL has been labelled with125I and a specific activity of 100 μCi/μgm of HPL has been attained. Dextran-coated charcoal has been employed to separate the bound from the free hormone in radioimmuno-assay. The sensitivity of this technique has been found to be 0.2 ng of HPL. Intraassay and inter assay variations have been found to be less than 10%. This procedure has been adopted to establish the normal range of HPL in pregnant women at different periods of gestation, and to evaluate risk pregnancies.

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Abstract  

A method has been developed for the radiassay of serum vitamin B12 using a competitive binding technique. By this method, vitamin B12 levels as low as 50 pg per ml of serum can be estimated in test samples. Egg yolk has been used as a test binding protein, which has several advantages over serum or plasma protein binding agents, as described in this paper. This binder is quite suitable and reliable for the assay of vitamin B12.

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