Hydride generation atomic fluorescence spectrometric determination of ultratraces of selenium and tellurium in cow milk

A sensitive procedure has been developed for selenium and tellurium determination in milk by hydride generation atomic fluorescence spectrometry (HG-AFS) after microwave-assisted sample digestion. The method provides sensitivity values of 1591 and 997 fluorescence units ng⁻¹ ml⁻¹ with detection limits of 0.005 and 0.015 ng ml⁻¹ for Se and Te, respectively. The application of the developed methodology to the analysis of cow milk samples of the Spanish market evidenced the presence of concentration ranges from 11.1 to 26.0 ng ml⁻¹ for Se, and from 1.04 to 9.7 ng ml⁻¹ for Te having found a good comparability with data obtained after dry-ashing of samples.     

醌亚胺类碱性染料在极谱分析中的应用——用天青Ⅰ测定痕量亚硝酸根

本文提出一个基于在酸性介质中,是青Ⅰ与NO_2~-发生亚硝化反应单扫描示波极谱法测定痕量NO_2~-的新方法。在0.06mol/L盐酸介质中。天青Ⅰ的亚硝化产物于-0.65V(vs.SCE)产生一灵敏的二次导数峰。峰高与NO_2~-浓度在0.002～0.24μg/mL范围内成直线关系。方法应用于水样、土壤中NO_2~-的测定,结果满意。     

Synthesis and Crystal Structure of （Et4N）2[Pd2（mp）2（mpH）2]

ＳｙｎｔｈｅｓｉｓａｎｄＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆ（Ｅｔ_４Ｎ）_２［Ｐｄ_２（ｍｐ）_２（ｍｐＨ）_２］ＳｈｉＪｉ－Ｃｈｅｎｇ；ＨｕａｎｇＸｉａｏ－Ｙｉｎｇ；ＷｅｎＴｉｎｇ－Ｂｉｎ；ＤｅｎｇＹｕ－Ｈｅｎｇ；ＣｈｅｎｇＣｈａｎｇ－Ｎｅｎｇ；Ｌｉ?..     

Application of recoverable nanosized palladium(0) catalyst in Sonogashira reaction

In the absence of ligand, copper and amine, a recoverable nanoparticle palladium(0) catalyzed Sonogashira reaction of aryl iodides and bromides with terminal alkynes was developed. The protocol involved the use of an environmental-friendly reaction system with ethanol as the solvent, potassium carbonate as a base, and poly(vinylpyrrolidone) (PVP) supported nanosized palladium metal colloids as the catalyst. The palladium metal was recovered and recycled by a simple decantation of the reaction solution and used for eight consecutive trials without significant loss of its reactivity.     

New palladium nanoclusters. Synthesis,structure, and catalytic properties

The reduction of palladium(ii) carboxylates Pd₃(OCOR)₆ (R = Me, Et, CHMe₂, CMe₃) with hydrogen in alcohol solutions containing 1,10-phenanthroline (phen) and subsequent oxidation with oxygen gave new palladium nanoclusters, mainly particles with a nearly spherical metal core and an average size of 18 . Based on elemental analysis, NMR, X-ray photoelectron spectroscopy, and EXAFS, nanoclusters were described by the idealized formula Pd₁₄₇phen₃₂O₆₀(OCOR)₃₀. The specimens contained up to 25% smaller 55-atomic Pd clusters with a 10 metal core. New nanoclusters catalyze hydrogenation of alkynes and alkenes, reduction of nitriles with formic acid, oxidation of aliphatic and benzylic alcohols, oxidative esterification of ethylene and propylene, and disproportionation of benzyl alcohol into toluene and benzaldehyde.     

Synthesis of Polyacrylaminothiourea Chelating Fiber and Properties of Concentration and Separation of Trace Noble Metal Ions from Samples

A novel polyacrylaminothiourea chelating fiber was synthesized simply and rapidly from nitrilon (an acrylonitrile-based synthetic fiber), which was applied to preconcentrate and separate of trace amount of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ） and Ir (Ⅳ） ions from solution of samples.The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 20.0mL/min at pH2, and can also be desorbed with 15 mL of 4mol/L HCl 3% thiourea from the fiber column with recoveries of 96.5%-100%.The chelating fiber can be reused for ten times,the recoveries of these ions are still over 92%,and hundred to thousand times of excess of Fe(Ⅲ）,Al（Ⅲ）,Ca(Ⅱ），Mg（Ⅱ）,Ni(Ⅱ）,Mn（Ⅱ),Cu(Ⅱ），Zn(Ⅱ），and Cd(Ⅱ） cause no interference on the determination of the analyzed ions by inductively-coupled plasma atomic emission spectrometry (ICP-AES).The static saturation adsorption capacities of the fiber for the analytes are in the range of 1.15-2.80mmol/g.The relative standard deviations for the determination of 20.0ng/mL each of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ）and Ir(Ⅳ） are in the range of 0.7%-3.0%.The recoveries for test from standard additions to real solution samples are between 96% and 100%.The concentration of each ion in powder sample detected by the method is in good agreement with the certified value.     

Multivariate resolution of NMR labile signals by means of hard- and soft-modelling methods

One of the difficulties frequently encountered when studying acid–base equilibria with NMR spectroscopy is the labile behaviour of the measured signal, which hinders the application of bilinear multivariate data analysis methods. In this work, a mathematical transformation is proposed for the conversion of NMR labile signals to inert signals, which make possible the application of multivariate data analysis methods, based on bilinear data models. The procedure has been applied to the analysis of NMR data corresponding to the acid–base equilibria of nucleotides dCMP and dGMP. Both hard-modelling (EQUISPEC) and soft-modelling (MCR-ALS) approaches have been applied for the analysis and resolution of transformed bilinear NMR data matrices.     

化学光谱法测定5N氧化钆中14个稀土杂质元素

报道了化学光谱法测定５Ｎ高纯氧化钆中１４个稀土杂质元素，在Ｐ５０７萃淋树脂色层柱上分离氧化钆中稀土杂质元素，分别采用定量分离Ｌａ－Ｓｍ及Ｔｂ－Ｌｕ＋Ｙ和部份分离Ｅｕ的方法，并相应地采用碳粉吸附法和碳粉粉末法进行光谱测定。分离时间为３．５ｈ，测定下限为１．２μｇ／ｇ（ＲＥ）。     

离子液体中用Heck反应合成2-取代萘烯丙醇化合物

利用Heck反应, 在离子液体、金属钯或镍、碱和膦配体反应体系中, 由卤代萘与烯丙醇反应, 制得了高收率和高选择性的2-取代萘烯丙醇化合物. 该方法原料便宜易得、操作简单、反应体系可循环使用. 并讨论了醋酸镍替代醋酸钯、不同膦配体、溶剂及碱对反应转化率的影响. 通过核磁共振、红外光谱、质谱和元素分析对产物的结构进行了表征.