焙烧温度对二甲醚水蒸气重整制氢 Cu/ZnO/Al2O3/Cr2O3+H-ZSM-5双功能催化剂性能的影响

采用共沉淀耦合机械混合法制备了Cu/ZnO/Al₂O₃/Cr₂O₃+H-ZSM-5双功能催化剂,并用于二甲醚水蒸气重整制氢反应,结合热重、傅里叶红外光谱、XRD、BET、H₂-TPR表征,考察了焙烧温度对Cu/ZnO/Al₂O₃/Cr₂O₃催化剂物理化学性质及双功能催化剂催化性能的影响。研究结果表明,400℃焙烧时,析出CuO粒子的同时伴有尖晶石相,进而在反应过程中对金属铜粒子起到良好的隔离作用。而焙烧温度较低时,催化剂分解不完全,催化剂活性位较少。焙烧温度大于500℃时,CuO粒子发生二次团聚,同时尖晶石相大量生成,造成催化剂活性位减少,活性较低。合适的焙烧温度为400℃,此时二甲醚转化率为92.9%,氢气收率可达到76.5%,具有较好的反应效果。     

Spectrophotometric determination of molybdenum(vi) with benzoylacetanilide

Abstract

The complex formed between molybdenum(VI) and benzoylacetanilide in the pH range 0.6 and 1.9 has been extracted into methyl isobutyl ketone and the absorbance has been measured at 410 mμ. Quantities of 0.15 to 2.10 mg of molybdenum have been determined with a standard deviation of 0.6%. The color is stable up to 2 hours. The presence of Co²⁺, Ni²⁺, Zn²⁺, Mn²⁺, Be²⁺, Al³⁺, Cr³⁺, Ce⁴⁺, Th⁴⁺ or UO²⁺ ₂ up to 100 μg causes no interference. Ordinarily, Fe³⁺ interferes with the determination, but when masked with 1 ml of 0.5% solution of ascorbic acid the tolerance limit is 10 mg. Thus, molybdenum can be determined in steel when present in amounts as low as 0.26%.     

中温固体氧化物燃料电池LaNi0.6Fe0.4O3-δ阴极材料的制备及性能表征

以硝酸镧、硝酸镍和硝酸铁为原料,柠檬酸作燃料低温燃烧合成固体氧化物燃料电池阴极材料LaNi0.6Fe0.4O3-δ.X射线衍射（XRD）图谱显示,600℃煅烧可形成单一的LaNi0.6 Fe0.4 O3-δ钙钛矿相.电子显微镜（TEM和SEM）照片看出,其颗粒尺寸〈100 nm.电池交流阻抗谱图表明,在1050℃烧结制...     

Spectrophotometric Determination of U(VI) with Rifampicin in Soil Samples

A validated spectrophotometric method has been developed for the determination of uranyl ion in soil samples. The method is based on the complexation reaction between uranyl ion and rifampicin in methanol‐water medium at room temperature. The method is followed spectrophotometrically by measuring the absorbance at 375 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration range of 1.35–20.25 μg mL^‐1 with apparent molar absorptivity and Sandell's sensitivity of 8.0 × 10³ L mol^‐1cm^‐1 and 0.042 μg/cm²/0.001 absorbance unit, respectively. The interference of a large number of anions and cations has been investigated and the optimized conditions developed have been utilized for the determination of uranium(VI) in soil samples. The three sigma detection limit (n = 9) for uranyl ion was found to be 0.20 μg mL^‐1. The proposed method was successfully applied to the determination of uranyl ion in soil samples.     

Determination of Cr(VI) by portable tungsten coil electrothermal atomic absorption spectrometer after surfactant-assisted dispersive liquid-liquid microextraction

As a new developed instrument, a portable tungsten coil electrothermal atomic absorption spectrometer (W-coil ET-AAS) was first coupled with surfactant assisted dispersive liquid–liquid microextraction (SA-DLLME) to improve its analytical performance and expand its applications in this work. SA-DLLME was very simple, rapid and the extraction efficiency was considerably improved by the effect of surfactant, which was suitable to be coupled with the portable instrument in field analysis. After SA-DLLME, concentrated chromium in organic phase was directly determined on W-coil atomiser. The influence factors relevant to SA-DLLME and instrumental conditions were studied systematically. Under the optimal conditions, the limit of detection (LOD) for Cr(VI) was 0.016 µg L^?1, with sensitivity enhancement factor (EF) of 107. The relative standard deviation (RSD) for seven replicate measurements of 0.5 µg L^?1 of Cr(VI) was 4.6%. The recoveries for the spiked samples were in the acceptable range of 96.8–104%. The rapid, simple and high effective method greatly improved the sensitivity of this portable spectrometer for the determination of Cr(VI) and was applied to the analysis of ultra-trace Cr(VI) in real and certified water samples with satisfactory results.     

Determination of asperosaponin VI in rat plasma by HPLC‐ESI‐MS and its application to preliminary pharmacokinetic studies

Asperosaponin VI (also named akebia saponin D) is a typical bioactive triterpenoid saponin isolated from the rhizome of Dipsacus asper Wall (Dipsacaceae). In this work, a sensitive high‐performance liquid chromatography–electrospray ionization–mass spectrometry (HPLC‐ESI‐MS) assay has been established for determination of asperosaponin VI in rat plasma. With losartan as the internal standard (IS), plasma samples were prepared by protein precipitation with methanol. Chromatographic separation was performed on a C₁₈ column with a mobile phase of 10 mm ammonium acetate buffer containing 0.05% formic acid–methanol (32 : 68, v/v). The analysis was performed on an ESI in the selected ion monitoring mode using target ions at m/z 951.4 for asperosaponin VI and m/z 423.2 for the IS. The calibration curve was linear over the range 3–1000 ng/mL and the lower limit of quantification was 3.0 ng/mL. The intra‐ and inter‐assay variability values were less than 9.5 and 7.8%, respectively. The accuracies determined at the concentrations of 3.0, 100.0, 300.0 and 1000 ng/mL for asperosaponin VI were within ±15.0%. The validated method was successfully applied to a pharmacokinetic study in rats after oral administration of asperosaponin VI. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of molybdenum(VI) by differential pulse polarographic technique using 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D)

A novel analytical reagent 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D) was synthesized for the determination of molybdenum(VI). The present paper reveals the detailed study of electroanalytical behaviour for [Mo-(4-2-HPEDB-1,3,D)] complex under optimized conditions. The peak obtained for [Mo-(4-2-HPEDB-1,3,D)] prevent the interference of foreign ions which shows the sensitivity of the proposed method. The linearity was maintained at the concentration range of 0.5–200 μg/mL at pH 4.5 with correlation factor 0.9997. The present method was successfully applied for the analysis of molybdenum(VI) in biological fluids and plant material. The results obtained from the proposed method show good agreement with reference method.     

原子吸收光谱法研究双水相体系对铬的选择性萃取分离效率

研究了乙醇-硫酸铵双水相体系对Cr(Ⅵ)的选择性萃取分离效率及其原子吸收光谱法(AAS)分析. 配制乙醇-硫酸铵双水相体系, 并考察不同种类盐, 盐用量, 酸度和时间对体系萃取分离效率的影响, 用AAS法测定体系对以重铬酸根形式存在的Cr(Ⅵ)的选择性萃取分离效率, 通过乙醇和水相的AAS法测定选择了最佳萃取分离条件, 在pH为4的酸性介质中把水相中的Cr(Ⅵ)萃取到乙醇相而Cr(Ⅲ)留在水相中, 使两种形态的铬彼此分离, 通过对醇相Cr(Ⅵ)和水相Cr(Ⅲ)的 AAS测定, 得到最佳测定条件及体系对Cr(Ⅵ)的萃取率为: 双水相体系的体积为10.0 mL, V(EtOH)∶V(H2O)=2∶3, (NH4)2SO4的质量为1.7 g, pH 4, Cr(Ⅵ)萃取率为90% 以上, Cr(Ⅲ)回收率为98%～108%. 本法可用于铬的形态分析.     

Carbon nanotube composite coated platinum electrode for detection of Cr(III) in real samples

This paper demonstrates the application of composite multi-walled carbon nanotube (MWNT) polyvinylchloride (MWNT-PVC) based on 1,5-diphenylcarbazide as chromium ionophore in potentiometric measurement. The sensor shows a good Nernstian slope of 19.52 ± 0.40 mV/decade in a wide linear range concentration of 6.3 × 10⁻⁸ to 1.0 × 10⁻² M for Cr(NO₃)₃. The detection limit of this electrode was found to be 3.2 × 10⁻⁸ M of Cr(NO₃)₃ and is applicable in a pH range of 3.0-6.8. It has a short response time of about 10 s. This chromium electrode has a good selectivity over 16 various metal ions. The practical analytical utility of this electrode was demonstrated by measurement of Cr(III) in drinking water and mineral water samples without any serious preliminary pre-treatment and chromium in multivitamin.     

Solid phase extraction and preconcentration of uranium(VI) and thorium(IV) on Duolite XAD761 prior to their inductively coupled plasma mass spectrometric determination

A simple and effective method is presented for the separation and preconcentration of thorium(IV) and uranium(VI) by solid phase extraction on Duolite XAD761 adsorption resin. Thorium(IV) and uranium(VI) 9-phenyl-3-fluorone chelates are formed and adsorbed onto the Duolite XAD761. Thorium(IV) and uranium(VI) are quantitatively eluted with 2 mol L⁻¹ HCl and determined by inductively coupled plasma-mass spectrometry (ICP-MS). The influences of analytical parameters including pH, amount of reagents, amount of Duolite XAD761 and sample volume, etc. were investigated on the recovery of analyte ions. The interference of a large number of anions and cations has been studied and the optimized conditions developed have been utilized for the trace determination of uranium and thorium. A preconcentration factor of 30 for uranium and thorium was achieved. The relative standard deviation (N = 10) was 2.3% for uranium and 4.5% for thorium ions for 10 replicate determinations in the solution containing 0.5 μg of uranium and thorium. The three sigma detection limits (N = 15) for thorium(IV) and uranium(VI) ions were found to be 4.5 and 6.3 ng L⁻¹, respectively. The developed solid phase extraction method was successively utilized for the determination of traces thorium(IV) and uranium(VI) in environmental samples by ICP-MS.