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121.
122.
A new type of a reactor column, a crushed BaSO4 reactor column used for the flow injection spectrophotometric determination of sulfate ion using the exchange reaction of sulfate ion and barium-dimethylsulfonazo III is proposed. The column is very simple and economical. It can be continuously used for 8 h before washing with water for repeated usage of at least 1 month. The procedure is sensitive. Application to various water samples was demonstrated. 相似文献
123.
124.
125.
Piyanat Issarangkura Na Ayutthaya Chonnipa Yeerum Kullapon Kesonkan Kanokwan Kiwfo Kate Grudpan Norio Teshima Hiroya Murakami Monnapat Vongboot 《Molecules (Basel, Switzerland)》2021,26(15)
A simple flow injection FlameAAS for lead determination with an alginate-polyurethane composite (ALG-PUC) monolithic in-valve column has been developed. The ALG-PUC monolithic rod was prepared by mixing methylene diphenyl diisocyanate with polyol and sodium alginate with the ratio of 2:1:1 by weight for a 5 min polymerization reaction. It was then put into a column (0.8 cm i.d × 11 cm length) situated in a switching valve for the FI set up. A single standard calibration could be obtained by plotting the loaded µg Pb2+ vs. FI response (absorbances). The loaded µg Pb2+ is calculated: μg Pb2+ = FRload × LT × CPb2+, where the FR load is the flow rate of the loading analyte solution (mL min−1), LT is the loading time (min), and CPb2+ is the Pb2+ concentration (µg mL−1). A linear calibration equation was obtained: FI response (absorbances) = 0.0018 [µg Pb2+] + 0.0032, R2 = 0.9927 for 1–150 µg Pb2+, and RSD of less than 20% was also obtained. Application of the developed procedure has been demonstrated in real samples. 相似文献
126.
Blanchard M Alfredsson M Brodholt J Price GD Wright K Catlow CR 《The journal of physical chemistry. B》2005,109(46):22067-22073
Plane-wave density functional calculations are used to investigate the pressure dependence of the geometry and Gamma-point phonons of FeS(2) pyrite up to 150 GPa. The linear response method is employed to calculate the vibrational properties. Raman-active modes are in excellent agreement with the experimental data available up to 50 GPa,(1) and we predict the evolution with pressure of the IR-active modes for which no high-pressure spectroscopic data have been reported so far. Over the wide pressure range investigated here, all vibrational frequencies depend nonlinearly on pressure; their pressure dependence is quantified by determining the full set of mode Grüneisen parameters and their pressure derivatives. 相似文献
127.
Kateřina Liberková-Šebková Libor Červený Raymonde Touroude 《Research on Chemical Intermediates》2003,29(6):609-617
Effects of the precursor of active metal and of the reduction temperature upon activity and selectivity in selective hydrogenation of crotonaldehyde by Pt/SnO2 and Ru/SnO2 catalysts were studied. Experiments were performed in the liquid phase with a group of solvents tested: propan-2-ol, toluene, hexane and tetrahydrofuran. The best results were achieved with catalysts from ex-nitrate precursors/Pt(NH3)4(NO3)2 and Ru(NO)(NO3)2/reduced at 150° C. Propan-2-ol was evaluated as the most appropriate solvent to gain high yields of crotylalcohol in this study. A new hydrogenation product, 2-methylprop-2-en-1-ol (methallylalcohol), was observed. 相似文献
128.
The first experimental data are given for (e,2e) ionization from laser-aligned atoms. A linearly polarized laser excited Mg atoms to the 31P? state prior to ionization by low energy electrons. The scattered and ejected electrons were detected in coincidence and the differential cross section determined for a range of alignment angles. An asymmetric coplanar geometry was used, with one electron fixed and the other detected at different angles. The data are compared to that from the spherically symmetric 31S? state. Significant differences are found, in both magnitude and angular distribution. 相似文献
129.
Nancy Redman-Furey Kate Poiesz James Miller Carol Grundner 《Journal of Thermal Analysis and Calorimetry》2010,102(2):633-639
The thermal behavior of [Ca(H2O)3(2,3-pydcH)2]
n
(I), [Cd(H2O)3(2,3-pydc)]
n
(II), and [Cd(H2O)6][Cd(2,3-pydcH)3]2 (III) complexes with pyridine-2,3-dicarboxylic acid was monitored by TG, DTG, and DSC analysis, where 2,3-pydcH—mono deprotonated
pyridine-2,3-dicarboxylic acid and 2,3-pydc—doubly deprotonated dicarboxylate anion. Thermal decomposition of these compounds
go through one or two dehydratation stages, followed by the loss of organic matter. The final decomposition products are found
to be the corresponding metal oxides. The possible scheme of destruction of the complexes have been used to reveal the relationships
between stability and molecular structure. 相似文献
130.
Tanikkul S Jakmunee J Rayanakorn M Grudpan K Marquardt BJ Gross GM Prazen BJ Burgess LW Christian GD Synovec RE 《Talanta》2003,59(4):809-816
A novel Raman sensor using a liquid-core optical waveguide is reported, implementing a Teflon-AF 2400 tube filled with water. An aqueous analyte mixture of benzene, toluene and p-xylene was introduced using a 1000 μl sample loop to the liquid-core waveguide (LCW) sensor and the analytes were preconcentrated on the inside surface of the waveguide tubing. The analytes were then eluted from the waveguide using an acetonitrile-water solvent mixture injected via a 30 μl eluting solvent loop. The preconcentration factor was experimentally determined to be 14-fold, in reasonable agreement with the theoretical preconcentration factor of 33 based upon the sample volume to elution volume ratio. Raman spectra of benzene, toluene and p-xylene were obtained during elution. It was found that analytically useful Raman signals for benzene, toluene and p-xylene were obtained at 992, 1004 and 1206 cm−1, respectively. The relative standard deviation of the method was 3% for three replicate measurements. The limit of detection (LOD) was determined to be 730 ppb (parts per billion by volume) for benzene, exceptional for a system that does not resort to surface enhancement or resonance Raman approaches. The Raman spectra of these test analytes were evaluated for qualitative and quantitative analysis utility. 相似文献