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The present article describes a working or combined calibration curve in laser-induced breakdown spectroscopic analysis, which is the cumulative result of the calibration curves obtained from neutral and singly ionized atomic emission spectral lines. This working calibration curve reduces the effect of change in matrix between different zone soils and certified soil samples because it includes both the species' (neutral and singly ionized) concentration of the element of interest. The limit of detection using a working calibration curve is found better as compared to its constituent calibration curves (i.e., individual calibration curves). The quantitative results obtained using the working calibration curve is in better agreement with the result of inductively coupled plasma–atomic emission spectroscopy as compared to the result obtained using its constituent calibration curves. 相似文献
53.
Anshu Dandia Ruby Singh Dharmendra Singh Ashok Laxkar Asha Sivpuri 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2472-2479
A dry media procedure has been developed for the synthesis of a series of new class of pyrazolo [4,3-c][1,5]benzothiazepines 6 under microwave irradiation using montmorillonite K10 as solid support. The catalyst can be recovered and reused. Thus, the procedure provides a simple and green synthetic methodology under environmentally friendly conditions. Antifungal screening of synthesized compounds has shown promising activity. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
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S. L. Ashok Kumar M. Saravana Kumar S. Jegan Jenniefer P. Thomas Muthiah A. Sreekanth 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1110-1118
Abstract Bisthiocarbohydrazone derivatives of three heterocyclic ketone ligands, having a flexible coordination ability; 1, 5-bis (2-acetylthiophene) thiocarbohydrazone; 1, 5-bis (2-acetylfuran) thiocarbohydrazone; and 1, 5-bis (2-acetylpyrrole) thiocarbohydrazone were synthesized and characterized by elemental analysis, UV-visible, FT-IR, cyclic voltammetry, and 1H and 13C-NMR spectral studies. All bisthiocarbohydrazone exhibited the thioketone—thioenol tautomeric forms, as evidenced by IR spectral data and single crystal X-ray diffraction studies of 1, 5-bis (2-acetylfuran) thiocarbohydrazone and 1, 5–bis (2-acetylpyrrole) thiocarbohydrazone. Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables. 相似文献
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Ashok K. S. Chauhan Arun Kumar R. C. Srivastava 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):1057-1062
Abstract Activated tellurium, but not selenium, reacts with para-substituted benzoylmethyl bromides as well as with iodoacetamide at their melting points in absence of a solvent to give bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC6H4COCH2)2TeBr2, (Y = H, Me, and MeO) and bis(acetamido)tellurium diiodide, (H2NCOCH2)2TeI2, respectively. Quick reduction of (p-YC6H4COCH2)2TeBr2, with sodium metabisulphite in a two-phase system yields crystalline (p-YC6H4COCH2)2Te. These tellurides undergo smooth oxidative addition of halogens, interhalogen ICl or a pseudohalogen (SCN)2. Intramolecular coordination of the carbonyl group in these functionalized diorganotellurium dihalides is evident from IR spectra and shorter Te···O (carbonyl) distances in comparison to the sum of van der Waals radii and completes six coordination around Te atom. Not unexpectedly, therefore, intermolecular secondary bonding effects of the type Te…O, Te···X and X···X are missing in (PhCOCH2)2TeBr2, (p-MeOC6H4COCH2)TeBr2 and (PhCOCH2)2TeI2. Instead, these compounds provide rare examples, among organotellurium compounds, of supramolecular architecture, where C–H···Br and C–H···O hydrogen bonds and π-π (phenyl ring) interactions appear to be the noncovalent intermolecular associative forces that dominate the crystal packing. 相似文献
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A simple, rapid, and precise reversed-phase high-performance liquid chromatographic method for the simultaneous determination of lamivudine, tenofovir disoproxil fumarate and efavirenz in bulk and tablet dosage form has been developed and validated. Chromatography was performed on a 150 mm × 4.6 mm i.d., 5-μm particle, Phenomenex Luna C18 column with 30: 45: 25 (v/v/v) acetonitrile: methanol: water as mobile phase at a flow rate of 0.5 mL/min. UV detection was done at 258 nm; lamivudine, tenofovir disoproxil fumarate and efavirenz were eluted with retention times of 3.27, 4.58 and 10.90 min, respectively. The method was validated in accordance with ICH guidelines. Validation revealed the method is specific, rapid, accurate, precise, reliable and reproducible. Calibration plots were linear over the concentration ranges 1–6 μg/mL for lamivudine and tenofovir disoproxil fumarate and 2–12 μg/mL for efavirenz. Limits of detection were 0.05, 0.09 and 0.11 μg/mL and limits of quantification were 0.15, 0.28 and 0.34 μg/mL for lamivudine, tenofovir disoproxil fumarate and efavirenz, respectively. The high recovery and low coefficients of variation confirm the suitability of the method for the simultaneous determination of these three drugs in bulk and tablets. 相似文献
60.
Vikas Verma Kuldeep Singh Ashok Kumar Devinder Kumar 《Journal of Thermal Analysis and Calorimetry》2013,112(1):339-344
The use of unconventional synthesis methods in the formation of CaO·2Al2O3 (CA2) is justified because it reduces the formation temperature of the compound. CA2 is formed by classical method at temperatures above 1,400 °C. The polymeric precursor method allows a significant temperature decrease in CA2 synthesis reaching temperatures of 1,000 °C. This paper deals with CA2 synthesis by “citrate” method which is often presented as Pechini method, starting from a mixture of citric acid, ethylene glycol and calcium, and aluminum nitrates. A method based on the formation of a polymeric precursor was also used, starting from a mixture of acrylic acid and nitrates of calcium and aluminum. The results showed a net difference in favor of samples obtained from acrylic acid, which by annealing at 800 °C for 1 h, contain pure CA2. The samples obtained from citric acid, after annealing at 800 °C are amorphous. After annealing at 900 °C in all samples CA2 is single phase. 相似文献