Direct determination of mercury in cosmetic samples by isotope dilution inductively coupled plasma mass spectrometry after dissolution with formic acid

A new method was proposed for the accurate determination of mercury in cosmetic samples based on isotopic dilution (ID)-photochemical vapor generation (PVG)-inductively coupled plasma mass spectrometry (ICP MS) measurement. Cosmetic samples were directly dissolved in formic acid solution and subsequently subjected to PVG for the reduction of mercury into vapor species following by ICP MS detection. Therefore, the risks of analyte contamination and loss were avoided. Highly enriched ²⁰¹Hg isotopic spike is added to cosmetics and the isotope ratios of ²⁰¹Hg/²⁰²Hg were measured for the quantitation of mercury. With ID calibration, the influences originating from sample matrixes for the determination of mercury in cosmetic samples have been efficiently eliminated. The effects of several experimental parameters, such as the concentration of the formic acid, and the flow rates of carrier gas and sample were investigated. The method provided good reproducibility and the detection limits were found to be 0.6 pg mL⁻¹. Finally, the developed method was successfully applied for the determination of mercury in six cosmetic samples and a spike test was performed to verify the accuracy of the method.     

PEMFC催化剂的研究：自制抗CO中毒Pt-Ru/C电催化剂的性质

用胶体法制备了抗CO中毒PEMFC阳极Pt-Ru/C电催化剂（标记为THYT－2）,对 比研究了THYT－2与Johnson Matthey (JM)公司同类品牌Pt-Ru/C催化剂的电化学及 其它物理化学性能。结果表明,THYT－2电催化剂在甲醇燃料电池和CO／H_2（Φ_ (CO) = 1 * 10~(-4)）的氢氧燃料电池中的电催化行为与JM催化剂相当,但THYT－ 2在低浓度CO氢气燃料中的电池性能更好。两种催化剂的其它物理化学性质具有类 似性：XPS分析结果表明THYT－2和JM催化剂 中都有三种不同价态的Pt存在：即金 属态Pt(0)、氧化态Pt(II)和Pt(IV)。HRTEM测试结果表明两种催化剂的粒径处在2 ～3 mn左右,这可能是它们拥有良好电化学性能的主要原因之一。本文还对催化剂 中Pt与Ru组分的分布和相互作用进行了讨论,提出了改进Pt-Ru/C电催化剂的思路 。     

Influences of the Hydrophobicity of the Heme-binding Pocket on the Properties and Functions of Cytochrome b_5 Mutants

IntroductionElectrontransferreactionsarethekeystepsinphoto synthesis ,respirationandmanyotherbiochemicalprocess es.1Cytochromeb5isaredoxproteinexistingwidelyinnature ,whichactsasanelectron carrierduringvariouselectrontransferprocessesinthebiologicalsystem .2Cytochromeb5isamembraneproteinwithmolecularweightofapproximately 16kDa ,ofwhichthehydrophobicC terminaldomainanchorscytochromeb5tothemem brane ,andthehydrophilicN terminaldomaincontainshemeprostheticgroupandexhibitsthebiologicalfunctionsof…     

Synthesis and Characterization of Bis(undeca-tungstoferrate) Lanthanates of Potassium

A series of novel rare earth complexes with 11-tungstoferrate as ligand, K15Ln(FeW11 O39)2 .xH2O(Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er or Yb) were prepared and characterized by elemental analyses, IR, UV-vis, polarograms, magnetic susceptibility and thermal measurement.Keywords Heteropoly complex, Rare earth complex, Synthesis, Bis(undecatungstoferrate) lanthanates of potassium     

芳烃金属配合物在有机合成中的应用

本文讨论了芳烃金属配合物中的芳香部份在与金属配合后性质上的变化,以及这些变化后的性质在有机合成中的应用。     

Effect of Demulsifiers on Dilatational Properties of Crude Oil–Water Interfaces

The dilatational properties of polyether demulsifiers PEA, PEB, PEC, PED, PEF, and PEG at the decane-water interface were investigated. Meanwhile, the effect of demulsifiers with different structures on interfacial dilatational modulus of diluted crude oil also was explored. The properties of demulsifiers are compared and analyzed in combine with the dilatational parameters at decane-water interface and at 5% crude oil-water interface. The results show that interfacial dilatational viscoelasticity could characterize the interfacial behavior of demulsifiers. The demulsifiers, which have different kinds or structures, have different effects on destroying the interfacial film of crude oil with increasing bulk concentration. Therefore, the dosage of demulsifier is a very important role in controlling nature of crude oil film.     

Synthesis and Magnetism of 2-Hydroxy-1,3-propylene-bis(oxamato)-bridged Co~ⅡCu~ⅡCo~Ⅱ Complexes

ＳｙｎｔｈｅｓｉｓａｎｄＭａｇｎｅｔｉｓｍｏｆ２┐Ｈｙｄｒｏｘｙ┐１，３┐ｐｒｏｐｙｌｅｎｅ┐ｂｉｓ（ｏｘａｍａｔｏ）┐ｂｒｉｄｇｅｄＣｏⅡＣｕⅡＣｏⅡＣｏｍｐｌｅｘｅｓＭＩＡＯＭｉｎｇ－ｍｉｎｇ，ＣＨＥＮＧＰｅｎｇ，ＬＩＡＯＤａｉ－ｚｈｅｎｇＪＩＡ...     

基于萘基块新型开链冠醚的合成及晶体结构研究

以3,6-二溴-2,7-二羟基萘为起始原料,经与2-溴-N-苯基乙酰胺醚化,再用硼氢化钠和三氟化硼乙醚还原得基于萘基块新型的开链冠醚,两步总收率为96%.利用单晶X衍射研究其结构,晶体为三斜晶系,P-1空间群,a=9.588(3),b=10.898(3),c=13.060(4),α=103.190(4)°,β=93.953(4)°,γ=115.622(5)°,V=1176.0(6)3,Z=2,Dc=1.571 g/cm3,λ=0.71075 nm,μ(Mo Kα)=3.472 mm-1,Mr=353.22,F(000)=560.在晶体结构中,分子中的一个N—H基团与另外一分子形成双分叉氢键N—H…Br和N—H…O,进而组装成二聚体.这些中心对称的二聚体进一步通过C—H…π相互作用叠加成二维层状结构平行于(110)面.     

Au57Ag53(C≡CPh)40Br12: A Large Nanocluster with C1 Symmetry

The controlled synthesis and structure determination of a bimetallic nanocluster Au₅₇Ag₅₃(C≡CPh)₄₀Br₁₂ (Au₅₇Ag₅₃) is presented. The metal core has a four‐shell Au₂M₃@Au₃₄@Ag₅₁ @Au₂₀ (M=1/3 Au+2/3 Ag) architecture. In contrast to the previously reported large nanoclusters that have highly symmetric kernel structures, the metal atoms in Au₅₇Ag₅₃ are arranged in an irregular manner with C₁ symmetry. This cluster exhibits excellent thermal stability and is robust under oxidative or basic conditions. The silver precursors play a key role in dictating the structures of the nanoclusters, which suggests the importance of the counteranions used.     

New Host Molecules with Imidazoliums as Functional Arms:Syntheses and Anion Recognition

The bridged tri-imidazoliums 3.3X^--5.3X^-(X^-=PF6^-,Br^-,I^-)and bis-imidazoliums 6.2PF6^- were synthesized by N-quaternization of imidazole derivative 1 in acetonitrile under reflux.UV spectroscopic titration experiments showed that the halide salts and hexafluorophosphate salts of these imidazoliums exhibited good recognition toward anions in water and in acetonitrile,respectively.