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  • Author or Editor: M. R. Khan x
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Abstract  

A simple X-ray fluorescence (XRF) spectrometric method for the determination of Cd, Hf, Hg, and Gd in uranium solution has been developed, where sample solutions were introduced to the XRF spectrometer directly in simple polyethylene bottles. The matrix effects have been rectified using standards of similar composition. Statistical evaluation has established it as a fast and reliable method applicable to trace analysis.

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Abstract  

The complexation of uranyl ion with acetate ions was investigated in 20% ethanolic solution by using cyclic voltammetry. The uranium formed 1:1 and 1:2 complexes with acetate ions. The values of log β1 and log β2 for uranyl acetate complexes were 2.05 ± 0.08 and 5.25 ± 0.06 respectively. The diffusion coefficient and heterogeneous rate constants for the reduction of uranyl ion at hanging mercury drop electrode in 20% ethanolic solution of acetate ions were 0.43 × 10−5 cm2 s−1 and 2.26 × 10−3 cm s−1, respectively. Thermodynamic parameters were also evaluated by finding the effect of temperature on the heterogeneous rate constants. The values of ΔH *, ΔS * and

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were 2.52 kJ mol−1, −43.8 J mol−1 K−1 and 15.57 kJ mol−1. The positive values of ΔH * and
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indicated that electrochemical reduction of uranyl ions in ethanolic solution of acetate ions is an endothermic and non-spontaneous process.

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A rapid, accurate, and sensitive reverse phase high-performance liquid chromatographic method was developed and validated for the simultaneous determination and quantification of glibenclamide and thymoquinone in rat plasma in the presence of internal standard (thymol). Chromatograms were developed with methanol, acetonitrile, and buffer (50:20:30, v/v/v) solvent system on a Symmetry® C18 (5 μm, 3.9 × 150 mm) column, and pH was adjusted to 4.5 with orthophosphoric acid. Mobile phase was pumped at a flow rate of 1.5 mL min−1 with 254 nm ultraviolet (UV) detection. Validation of the method was performed in order to demonstrate its selectivity, linearity, precision, accuracy, limits of detection, and quantification (LOD and LOQ). Standard curves were linear (r 2 = 0.996 and 0.999 for glibenclamide and thymoquinone) over the concentration range 0.5–50 μg mL−1. The coefficient of variation (CV) of < 6% and accurate recovery of 87.54–105.19% for glibenclamide and CV of <5% and accurate recovery of 86.08–103.19% for thymoquinone were found to be in the selected concentration range of 0.5–50 μg mL−1. The lower limits of detection and quantitation of the method were 0.109 and 0.332 μg mL−1 for glibenclamide and 0.119 and 0.361 μg mL−1 for thymoquinone, respectively. The within and between-day coefficients of variation were less than 7%. The validated method has been successfully applied to measure the plasma concentrations in a drug interaction study of glibenclamide with thymoquinone in an animal model to illustrate the scope and application of the method.

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Authors: N. K. Satti, M. Amina, P. Dutt, V. K. Sharma, P. Sharma, I. Khan, B. D. Gupta, K. A. Suri, S. C. Sharma, R. K. Johri and S. N. Sharma

Summary

In this paper we describe a sensitive and reproducible reversed-phase high-performance liquid chromatography (HPLC) method with photodiode-array detection for isolation and quantification of the bioactive hydrophilic constituent 7-(1-O-β-d-galacturonide-4′-(1-O-β-d-glucopyranosyl)-3′,4′,5,7-tetrahydroxyflavone, 1, from the seeds of Cuminum cyminum. Compound 1 was separated isocratically on a C18 preparative column, in high purity, after removal of solvents. The purity and identity of the compound were established by use of LC-mass spectrometry and by spectroscopic techniques (1H and 13C NMR). The purity of 1 was also confirmed by HPTLC.

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