Search Results
Abstract
Propoxur (Baygon®) is an insecticide with a broad spectrum of activity and a very low order of mammalian toxicity. Radiosynthesis of propoxur was performed by the reaction of acetyl-114C chloride and sodium azide to produce methyl isocyanate which then reacted with o-isopropoxyphenol at 100°C. A two compartment reaction tube with a break seal was utilized. Chromatographic procedures for isolating the N-methylcarbamates from their reaction mixtures are reported. Acetyl-1–14C chloride was prepared from thionyl chloride and sodium acetate-1–14C. Grignard reaction between methyl iodide and carbon –14 dioxide yielded acetic acid –14C which was neutralized by sodium hydroxide solution to give sodium acetate 1-14C.
Abstract
14C-Propoxur (Baygon®) was synthesized through the reaction of o-isopropoxyphenol with methyl isocyanate –14C. The product was isolated chromatographically on Florisil and crystallized from carbon tetrachloride. The purity and structure were confirmed using infrared spectra, melting point, co-chromatography on Florisil column, and silica-gel G thin layer chromatography. The purity was found to be at least 99%. The rate of absorption and other characteristics of14C-propoxur resistance inAnopheles Stephensi from the south coast ot Iran was investigated. The mortality of strain adults was 100% after a one hour exposure when 1 ppm14C-propoxur was used. Moreover, the mortality was not changed when a lower concentration (5 ppm) was used. On the other hand, the absorbance of14C-propoxur in several strains ofA. Stephensi has been determined. The identity and TLC characteristics of products formed after 1 and 2 hours exposure, respectively, to14C-propoxur have also been investigated.
Abstract
This work is part of a project with the IAEA, in a coordinated program on 
Trace Elements in Human and Bio-Environmental Systems
to evaluate their nutritional requirements, interrelations and the role of trace elements in health, metabolism, etc. Cow's milk being regarded as one of the most important and nutritious foodstuffs consumed by people. Hence as a first step, an elemental analysis for milk was carried out for this purpose; a few samples of pasteurized milk and local sample were investigated for essential and toxic trace elements. The secondary aim of this project was the assessment of various analytical techniques involved. However, in the present work, the methods involved were AAS, PIXE and NAA. The latter method was applied both instrumentally and radiochemically. Although the results pertaining to the various methods employed are not in good agreement. there is, however, some justification to clarify this internal inconsistency. The precision of NAA and AAS allows a greater degree of acceptance. Although PIXE is very fast and rather routine, the technique for trace element analysis needs certain adaptations and development.
Abstract
Extraction of technetium with dibenzo-18-crown-6 was studied from alkline media. Effects of crown cavity size, substitutions, organic solvents and type of base on the distribution coefficient were discussed. High separation factors of technetium from other elements in an irradiated uranium sample were attained.
Abstract
The measurement of uranium in human teeth and kidney stones has been carried out by using the fission track activation technique. In this determination 2759 and 2205 absolute counts of tracks /for standard: 6940 and 1556/ for teeth samples and 1689 tracks /for standard: 1446/ for kidney stone samples have been made, respectively. The results obtained by this technique are the following: Xtooth/1/=/0.227±0.006/ ppm, Xtooth/2/=/0.143±0.007/ ppm and Xkidney=/0.568±0.020/ ppm. The experimental method is described and the results discussed.
Abstract
The spatial distribution of neutrons was measured at the muon science laboratory of KEK by the activation detector method using an imaging plate for the radioactivity measurement. It was confirmed that this method is highly sensitive to detect the average neutron dose of 10 µSv/h. The distribution of thermal and epithermal neutrons was also measured in the experimental room. The cadmium ratio inside the experimental room is one except for the neutron leakage point. The spatial distribution of neutrons inside the concrete shield of KENS was measured by the same method. Aluminum and gold foils were used for the measurement of fast and thermal neutrons, respectively. Two dimensional change of the reaction rate of the 27Al(n,α)24Na reaction shows a good agreement with the results calculated by the Monte Carlo simulation using MARS14 code. Thermal and epithermal neutron flux ratio on the beam axis was measured by the cadmium ratio method. The flux ratios were about 30 and almost constant for every slot except for the surface of the shield, because the cadmium ratio is 2. This method was very useful to measure the activity of many pieces of detector simultaneously without any efficiency and decay correction. Wide dynamic range and high sensitivity are also the merit of this method.
A high-performance thin-layer chromatographic (HPTLC) method has been developed and validated as per ICH guidelines for simultaneous identification and quantification of the basic and acidic moieties of salmeterol xinafoate salt. Salmeterol xinafoate was split into two spots, salmeterol base and xinafoic acid at R F values 0.48 ± 0.02 and 0.36 ± 0.04, respectively, on pre-coated silica gel 60 F254 HPTLC plates using ethyl acetate-methanol-ammonia solution 33% (8:1.5:0.5 v/v) as a mobile phase. On the fluorescent plate, the spots were located by fluorescence quenching and spectrodensitometric quantification of salmeterol base was carried out at 300 nm and xinafoic acid at 250 nm under reflection-absorption mode. The calibration curves were linear in the range of 1–6 μg per spot for salmeterol base and 0.5–4 μg per spot for xinafoic acid with good correlation coefficients (0.9964, 0.9986), and percentage accuracy of 100.11 ± 0.84 and 99.13 ± 0.86, respectively. The proposed method was found to be reproducible for quantitative analysis of salmeterol xinafoate in drug substance, inhaled pharmaceutical dosage forms and spiked human urine and will serve in quality control analysis. Statistical analysis was performed and validation method has been estimated in terms of linearity range, limits of detection (LOD) and quantification (LOQ), accuracy and precision.
Two sensitive, specific, and selective stability-indicating chromatographic methods were developed for the determination of cyclobenzaprine HCl (CZ) and asenapine maleate (AS) in pure forms, in the presence of their degradation products and in their pharmaceutical formulations. The first method was an isocratic reversed-phase high-performance liquid chromatography (RP-HPLC). Analysis was performed on cyano column using a mobile phase consisting of acetonitrile–(0.05 m) potassium dihydrogen phosphate buffer (pH 3 ± 0.1) (70:30, v/v) with a flow rate of 1.5 mL min−1 and ultraviolet (UV) detection at 290 nm for the determination of CZ, and methanol–(0.05 m) potassium dihydrogen phosphate buffer (pH 6 ± 0.1) (70:30, v/v) with a flow rate of 1.5 mL min−1 and UV detection at 220 nm for the determination of AS. The second method was thin-layer chromatography (TLC), using silica gel 60 F254 plates and toluene–methanol–chloroform-ammonia solution 33% (5:3:6:0.1, by volume) as the mobile phase for the two drugs. The spots were scanned densitometrically at 290 and 220 nm for the determination of CZ and AS, respectively. The methods were validated according to the International Conference on Harmonization (ICH) guidelines, and the acceptance criteria for linearity, accuracy, precision, specificity, and system suitability were met in all cases. The linearity ranges were 2.5–25 μg mL−1 for the RP-HPLC method and 5–50 μg band−1 for the TLC method for both drugs. The limits of detection for the RP-HPLC method were 0.250 and 0.578 for CZ and AS, respectively, while the limits of quantification were 0.758 and 1.572 for CZ and AS, respectively. The limits of detection for the TLC method were 1.355 and 1.284 for CZ and AS, respectively, while the limits of quantification were 4.472 and 3.891 for CZ and AS, respectively. The results were compared statistically at a 95% confidence level with the reported methods. There were no significant differences between the mean percentage recoveries and the precisions of the two methods.
Lavender and rosemary are shrubs that have many medicinal uses. Like any other shrubs, they are susceptible to pest infection which needs pesticides treatment. Residues of pesticides in lavender and rosemary leaves may be hazardous to human health. The main objective of this study was to develop accurate and sensitive methods for the determination of residues of pesticides, namely, diazinon and chlorpyrifos, in lavender and rosemary leaves. Thin-layer chromatography (TLC) fractionation was applied to separate the desired pesticides to be analyzed and to determine the rate of the disappearance of these pesticides from lavender and rosemary leaves. Diazinon and chlorpyrifos were separated from extracts of leaves using silica gel 60 F254 plates. The mobile phase was formed of petroleum ether–ethanol–glacial acetic acid (9.5:0.5:0.1, v/v) and (9.0:1.0:0.1, v/v) as the developing systems for diazinon and chlorpyrifos, respectively, followed by densitometric measurement at 254 nm for both pesticides. The methods were validated over a range of 0.01–l.6 μg band−1 for diazinon and 0.04–2.0 μg band−1 for chlorpyrifos. The detection limits of diazinon and chlorpyrifos were 0.003 and 0.012 μg band−1, respectively. The safe harvest interval (pre-harvest interval; PHI), time in days between the last pesticide application to the crop and the time it can be safely harvested, was suggested to be 21 and 24 days for diazinon and chlorpyrifos, respectively. The developed TLC methods were used for sample cleanup and estimation of the studied pesticides residues in leaves extracts, in addition to the determination of the pre-harvest interval.
Two novel, sensitive, and selective stability-indicating chromatographic methods were described for the analysis of zopiclone (ZOP) in the presence of its degradation products, namely, 7-oxo-6,7-dihydro-5H-pyrrolo[3,4-b]pyrazin-5-yl-4-methylpiperazine-1-carboxylate (hydrolytic DEG) and 5H-pyrrolo[3,4-b]pyrazine-5,7(6H)-dione (oxidative DEG), in drug substance and product. The first method was an isocratic reversed-phase high-performance liquid chromatography (RP-HPLC) using Inertsil ODS3 (250 × 4 mm, 5 μm) column. Upon using HPLC, the run time could be reduced, and actually, the solvents consumption decreased. Quantification was achieved by detection wavelength at 237 nm, based on peak area. Chromatographic separation was performed over the range of 1–10 μg mL−1 with limits of detection (LOD) and quantification (LOQ) of 0.18 and 0.55 μg mL−1 and a mean recovery of 99.98 ± 0.55. The analysis was achieved at 30°C using a mixture of acetonitrile and water (50:50 v/v) as the mobile phase. The second method was thin-layer chromatography (TLC) applied for the separation and analysis of zopiclone in the presence of its alkaline, acidic, and oxidative degradation products. Chromatography was performed on silica gel 60 F254 plates with ethyl acetate‒methanol‒ammonia 33% (17:2:1 v/v) as the mobile phase. Successful resolution was observed with significant difference in the R F values, followed by densitometric measurement at 303 nm. Evaluation was carried out over the range of 0.1–2 μg per spot with a mean recovery of 100.52% ± 0.24. The developed methods were successfully applied to the analysis of ZOP in bulk powder, laboratory-prepared mixtures containing different percentages of its degradation products, and pharmaceutical dosage form. The degradation products were separated by HPLC as well as identified by TLC, infrared (IR), and mass spectrometry (MS) to confirm its structures and elucidate degradation pathway. The developed methods were validated as per the International Conference on Harmonization (ICH) guidelines. The results obtained by the proposed methods were statistically compared with the reported methods revealing high accuracy and good precision.
