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Abstract  

This paper presents a rapid and reasonably accurate mathematical solution to the estimation of radioisotopes produced by the intermittent neutron irradiation of targets in nuclear reactors including the points in time of attaining maximum activities for stopping the nuclear reaction for chemical processing. The formulae used in these estimations are presented.

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Abstract  

A set of rock and soil samples from Dome Beposo in the Amansie-West district of Ashanti Region of Ghana, suspected to contain gold, have been analyzed using instrumental neutron activation analysis (INAA) coupled with conventional counting techniques. The identification and quantification of the elements, gold, arsenic, mercury and antimony were done using 411.8 keV photopeak of 198Au, 559.1 keV photopeak of 76As, 77.3 keV photopeak of 197Hg and 564.2 keV photopeak of 122Sb. The precision and accuracy of the method were evaluated using standard reference materials. The precision and bias was found to be less than 6%. The first set of samples consists of ten rocks (GS), four of which retain moderate to quite high concentrations of gold, 0.27±0.01 mg/kg, 1.58±0.09 mg/kg, 7.51±0.44 mg/kg and 8.06±0.35 mg/kg, respectively. The second set comprises two soil samples taken from the upper and bottom layers of a gold exploration pit. Gold concentrations in upper (UL) and bottom (BL) layers are 0.06±0.002 mg/kg and 0.47±0.02 mg/kg, respectively. Arsenic was found in the soils as well as the rocks, and the levels ranged from 9.3±0.5 to 274±15.6 mg/kg. Mercury and antimony were found in the rocks only. Mercury levels in the rocks ranged between 0.11±0.004 and 9.67±0.42 mg/kg whilst antimony levels ranged from 0.21±0.01 to 6.88±0.38 mg/kg.

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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.

Open access

Summary

A new, simple, selective, precise, robust and stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been established for analysis of terbinafine hydrochloride (TH) in the bulk drug and in pharmaceutical formulations. Separation was achieved on aluminium plates precoated with silica gel 60F254, with toluene-ethyl acetate-formic acid 4.5:5.5:0.1 (v/v) as mobile phase. Densitometric analysis was performed at 284 nm. Compact bands of TH were obtained at R F 0.31 ± 0.02. Linearity (r 2 = 0.9985), limit of quantification (35 ng per band), recovery (97.6−101.6%), and precision (≤2.19) were satisfactory. The method was applicable for routine analysis and accelerated stability testing of TH in pharmaceutical drug-delivery systems. Because the method can effectively separate the drug from its degradation products, it can be used as a stability-indicating method.

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Journal of Thermal Analysis and Calorimetry
Authors:
S. K. Durrani
,
K. Saeed
,
A. H. Qureshi
,
M. Ahmad
,
M. Arif
,
N. Hussain
, and
T. Mohammad

Abstract

Yttrium aluminum garnet (YAG) and neodymium-doped yttrium aluminum garnet (Nd-YAG) nano-crystalline powders were successfully grown using cost effective sol spray process without the addition of any chelating agent or organic templates. Thermal decomposition behavior was studied by thermogravimetry (TG) and differential thermal analysis (DTA). Results revealed that crystallization of YAG started around 920 °C. The shrinkage/expansion behavior of synthesized powder was examined by dilatometer and revealing that sintering kinetics of these materials can be related to the evaporation of binder and formation of crystalline phases. Nano-crystallinity and garnet structure of YAG and Nd-YAG specimens were analyzed by Raman, fourier transform infra red (FTIR), and X-ray diffraction (XRD) techniques. XRD patterns were indexed using Rietveld refinement method. Smaller lattice parameter and a small change in atomic position of oxygen were found in Nd-YAG when compared with YAG structure. Scanning electron microscope (SEM) results indicated that particle size of Nd-YAG was <150 nm. The morphology of Nd-YAG nanosized powder was rounded in shape.

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High-performance thin-layer chromatography (HPTLC) method for the quantification of eugenol from nanostructured drug delivery systems was successfully developed and validated. The mobile phase consisted of n-hexane:acetone (7:3, v/v), and the densitometric scanning was performed in the absorbance mode at 280 nm. The method was valid with respect to linearity and range, accuracy, precision, specificity, detection limit (DL), and quantitation limit (QL). The linearity of the method was established by a correlation coefficient value of 0.9930 ± 0.0013. The precision was tested by checking intra-day (repeatability) and inter-day (intermediate precision) variations. The method was established to be precise by low relative standard deviation (RSD) values for different concentration of eugenol. The results of the recovery studies of eugenol from preanalyzed samples demonstrated the accuracy of the method. The specificity of the developed method for the analysis of eugenol in the nanoemulsion gel and nanoparticles samples was confirmed by comparing the spectra obtained in standard and sample analysis. The DL and QL were determined to be 31.41 and 95.17 ng band−1, respectively, for the HPTLC method. The forced degradation studies revealed on eugenol established the effectiveness of the developed and validated method. The developed and validated HPTLC method was found to be a stability-indicating one, as indicated by the results of forced degradation studies, for its use during the accelerated stability studies of the nanoemulsion gels and nanoparticles of eugenol.

Open access

Abstract

Coloring agents in foods and drinks have been popular for centuries. This study aims to analyze the presence of ten synthetic colors (namely, (allura red (E129), amaranth (E123), sunset yellow (E110), tetrazine (E102), fast green (E143), ponceau 4R (New Coccine) (E124), erythrosin B (E127), brilliant blue FCF (E133), brilliant black (E151) and carmoisine (E122))) in food and drink samples using ultra-high-performance liquid chromatography diode array detection (UHPLC-DAD). The present analytical method was carried out using Agilent Poroshell 120 HPH-C18 column, 3 × 100 mm, 2.7 µm, and a mobile phase consisting of 10 mM Na2HPO4, pH 7, mixed with methanol as a time-increment gradient solution until the time was 20 min, then decreased with time until the time was 26 min. The pH was set by orthophosphoric acid at 7 and 5 μL injection volume, 0.50 mL flow rate, and the elution systems were monitored at 428 nm for E102, 518 nm for E124, E110, E129, E122, 530 nm for E151, E127, 622 nm for E143, and E133, respectively. The limit of detection and quantification for all colors ranged from 0.017 to 0.025 and 0.057 and 0.082 mg L−1, respectively. The correlation coefficient values ranged between 0.9991 and 1.0. The selectivity of the assay revealed no interference from other components in the analyzed samples. The percent recovery and precision (intra- and inter-day) of the spiked samples were within the acceptable limits of the ICH guidelines. Five analytical parameters were employed, and the results showed a new, novel, and robust method according to ICH guidelines for analyzing these colors. While most of the investigated food and drinks fell within the accepted range, some fell outside. The current sample preparation and analytical methods are comprehensive and universal for extracting and measuring synthetic colors in various food and drink samples.

Open access
Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Paul
,
A. Valenta
,
I. Ahmad
,
D. Berkovits
,
C. Bordeanu
,
S. Ghelberg
,
Y. Hashimoto
,
A. Hershkowitz
,
S. Jiang
,
T. Nakanishi
, and
K. Sakamoto

Abstract  

We report here a search for the “live” 244Pu in 1 kg deep-sea dry sediment collected in 1992 in the North Pacific. After a 546 day alpha-counting of a Pu fraction chemically separated from the alkaline-fused sediment sample at Kanazawa University, AMS analysis was performed at Hebrew University and Weizmann Institute. Only one count of 244Pu with no background ions was detected, indicating no excess over the expected stratospheric man-made fallout. A limit of 0.2 atoms of 244Pu cm−2·y−1 for extra terrestrial deposition was set under reasonable assumptions and it was then concluded from this result and the available data on interstellar medium (ISM) that the abundance of 244Pu in the ISM is less than 2·10−11 g 244Pu (g·ISM)−1. Implications of the present result are discussed.

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Summary

An accurate, sensitive, precise, rapid and isocratic reversed-phase HPLC (RPHPLC) method for analysis of buspirone in the bulk drug and in solid dosage formulations has been developed and validated. The best separation was achieved on a 250 mm × 4.6 mm i.d., 5-μm particle, RP C18 column with 70:30 (υ/υ) methanol-0.01 m sodium dihydrogen phosphate buffer (pH 3.5) as mobile phase at a flow rate of 0.8 mL min−1. UV detection was at 244 nm. Response was a linear function of concentration over the range 0.05–20 μg mL−1 (r = 0.9998) and the limits of detection and quantitation were 3.7 and 11.3 ng mL−1, respectively. The method was validated in accordance with ICH guidelines. The drug was subjected to oxidative, hydrolytic, photolytic, and thermal stress. Degradation products produced as a result of this stress did not interfere with detection of buspirone and the assay can thus be regarded as stability-indicating. The method was used for quantification of buspirone in commercial buspirone tablets and to check content uniformity. The excipients present in the formulation did not interfere with the assay. The method is suitable for application in quality-control laboratories, because it is simple and rapid with good accuracy and precision.

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