电感耦合等离子体质谱法测定高纯金中痕量杂质

建立了高纯金中40余种痕量杂质的电感耦合等离子体质谱测定方法。方法检出限为0．0006～0．21μg/L。考察了基体Au的谱干扰及基体效应,采用Cs内标补偿基体对待测信号的抑制作用。方法简单、快速、灵敏、准确。     

Extraction inductively coupled plasma-optical emission spectrometry (ICP-OES) determination of traces of phosphorus in tungsten

A method for the separation and preconcentration of traces of phosphorus from tungsten was developed. Solid phase extraction of the phosphovanadomolybdate complex performed on a micro-column was applied. Phosphorus was determined by optical emission spectroscopy (OES) with inductively coupled plasma (ICP) excitation. A limit of detection of 0.4 g/g P with respect to the solid phase is obtained. By directly coupling the extraction/elution step to the ICP instrument a detection limit of 0.06 g/g P in W was achieved. Besides, the complexity of spectral evaluation in ICP-OES determinations of traces in spectralline-rich matrices is discussed.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Cluster assisted formation of carbon-carbon bonds: Synthesis and crystal structures of two trinuclear heterometallic complexes CpWRu2(CO)7(μ-H)[OC(NMe2)CCHCHEt] and CpWRu2(CO)6(μ-H)[OC(NMe2)CCH(μ-η2-C6H4)]

Treatment of the carbamoyl cluster Ru₃(CO)₁₀(-H)(-²-OC(NMe₂)] with a two molar excess of CpW(CO)₃CCⁿ Pr in refluxing toluene produced a heterometallic cluster complex CpWRu₂(CO)₇(-H)[OC(NMe₂) CCHCHEt] (II), whereas the heterometallic clusters CpWRu₂(CO)₆(-H)[OC(NMe₂)CCH(-²-C₆H₃X)] (IVb, X=H;IVc, X=Me;IVd, X=F) were isolated from the reactions with CpW(CO)₃CCC₆H₄X under similar conditions. Both complexesII andIV were generated via a complicated sequence involving hydride migration to the acetylide, fragmentation of the cluster via removal of a Ru(CO)_n unit, coupling with the carbamoyl ligand and C-H bond activation at the substituent. Crystal data forII: space group R ;a=26.605(3),c=17.934(2) Å,Z=18; finalR _F =0.032,R _w =0.034 for 2720 reflections withI>2(I). Crystal data forIVb: space group C 2/c;a=16.120(6),b=14.972(2),c=18.872(4) Å, =95.46(2)°,Z=8; finalR _F =0.0375,R _w =0.0375 for 2074 reflections withI>3(I).     

Synthesis, Structure, and Properties of the Cyclic Mixed Valence Oxothiotungstate [W8S8O8(OH)8(H3WO6]2−

The novel polyoxothioanion [W₈S₈O₈(OH)₈(H₃WO₆]^2– was prepared by acido-basic condensation of four [W₂S₂O₂]²⁺ thiofragments in the presence of tungstate ion. Rb₃[W₈S₈O₈(OH)₈(H₃WO₆]13H₂O was isolated in the solid state and fully characterized by X-ray diffraction study (monoclinic, C2/m [a=20.3540(1) Å; b=11.8042(2) Å; c=13.9355(2) Å; =90°; =131.134(1)°; =90°]. The molecular structure consists of an octameric {W₈S₈O₈(OH)₈} wheel encapsulating a central octahedron {H₃WO₆}^3–. The packing reveals a remarkable 3-D array resulting from connections between Rb⁺ and octameric wheels. The Rb⁺ cations form infinite parallel chains, which are mutually connected by the cyclic oxothioanions. The compound was also characterized by infrared spectroscopy and elemental analysis.     

Two-carrier liquid-phase synthesis of main-chain liquid crystalline oligomers and characterization of the products

Monodisperse oligomers were synthesized from terephthalic acid and -hydrogen--[oxy-1,4-phenyloxy-1,10-decamethyleneoxy-1,4-phenylene] using a polyethylene glycol support. Isolation of the target oligomers was achieved by use of a second soluble carrier which could be introduced and cleaved selectively, thus allowing to characterize the product chain in solution. The structures of the oligomers were assigned and identified using a combination of analytical methods such as electron impact mass spectrometry, IR- and ¹H-NMR spectroscopy and temperature-resolved pyrolysis-field ionization mass spectrometry (Py-FIMS).     

Determination of some trace elements in high-purity aluminium, zinc and commercial steel by AAS after preconcentration on amberlite XAD-1180 resin

The determination of trace metals, e.g. Bi, Cd, Pb, in high-purity aluminium, zinc and commercial steel by flame or graphite furnace atomic absorption spectrometry following their preconcentrations as iodo complexes on XAD-1180 resin by means of a short column system is described. The recoveries are quantitative (95%). The relative standard deviations varies between 6% and 10%. The relative errors are less than 8% in a concentration range of 1 × 10^–3 –4 × 10^–5%. Detection limits for flame AAS and GFAAS were in the ranges of 0.002–0.110 g/ml and 0.0003–0.004 g/ml or in the ranges of 0.08–4.40 g/g and 0.012–0.16 g/g with respect to the solid samples, respectively.     

Germylene complexes of tungsten pentacarbonyls W(CO)5GeCl2 and W(CO)5GeW(CO)5: Electrochemical synthesis and quantum-chemical computations

Convenient synthetic route to prepare the germylene complexes of tungsten pentacarbonyls, W(CO)₅GeCl₂ and W(CO)₅GeW(CO)₅, electrochemically is developed. Combined quantum-chemical/IR spectroscopic approach is used for identification of the synthesized compounds. Good agreement between theoretical and experimental spectra can be regarded as one of the proofs of their supposed structures.     

Profiling of illicit heroin samples by high-resolution capillary gas chromatography for forensic application

Summary Glass capillary gas chromatographic methods for profile analysis of trace impurities of illicit heroin samples have been developed. The procedure consists of extracting the impurities by toluene from acidic solution and examination by capillary GC. Derivatized and nonderivatized extracts of illicit heroin from different sources are reported. The reproducibility of the procedure and the detection with FID and N-FID are studied. Results obtained by application of the profiling procedure, as an additional pattern for comparison of samples in forensic casework, have shown the distinct advantage of this method.Presented at the 14th International Symposium on Chromatography London, September, 1982     

RP-HPLC Determination of Famotidine and its Potential Impurities in Pharmaceuticals

A simple, sensitive, and rapid reversed-phase high-performance liquid chromatographic method has been developed for determination of famotidine (FMT) and its impurities in pharmaceutical formulations. Separations were performed on a Supelcosil LC18 column with an isocratic mobile phase—13:87 (v/v) acetonitrile–0.1 M dihydrogen phosphate buffer containing 0.2% triethylamine (pH 3.0). The mobile phase flow rate was 1 mL min^–1 and the detection wavelength was 265 nm. Response was linearly dependent on concentration between 1 and 80 g mL^–1 (regression coefficient, R², from 0.9981 to 0.9999). RSD from determination of method repeatability (intraday) and reproducibility (interday) were <2% (n=6). Lowest detectable concentrations ranged from 0.08 to 0.14 g mL^–1. The proposed liquid chromatographic method can be satisfactorily used for routine quality control of famotidine in pharmaceutical formulations.     

Atomic emission and atomic absorption spectrometric analysis of high-purity powders for the production of ceramics

Summary Direct analysis methods and multistage combined analytical procedures for the determination of impurities at the g/g level and the upper ng/g level in high-purity powders of Al₂O₃, AlN, Si₃N₄ and SiC are described. Results obtained with a novel direct slurry-atomization technique using a Babington nebulizer and inductively coupled plasma optical emission spectrometry (ICP-OES) are presented. A comparison of analysis results of combined analytical procedures including wet chemical decomposition and determinations with graphite furnace atomic absorption spectrometry (ETAAS) or ICP-OES with those of slurry-atomization ICP-OES show the capabilities of this technique for routine analysis in production control. Detection limits for Al, B, Ca, Co, Cu, Fe, Mg, Mn, Si, Ti, W, V, and Zn in the matrices mentioned are between 0.03 and 2.5 g/g. For elemental concentrations 10 g/g relative standard deviations of the measurements are generally below 10%. The technique is shown to be a powerful tool for trace determinations in powder samples. This is shown by its use for analysis of a series of the ceramic powders mentioned and comparative results of other direct techniques such as total reflection X-ray fluorescence spectrometry and instrumental neutron activation analysis.

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OES und AAS von hochreinen Pulvern für die Keramikherstellung

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Herrn Prof. Dr. G. Tölg zum 60. Geburtstag von seinen Mitarbeitern gewidmet     

Determination of cadmium in orthophosphoric acid by graphite furnace atomic absorption spectrometry

Summary Cadmium has been determined in analytical-reagent grade orthophosphoric acids by direct graphite furnace atomic absorption spectrometry with Zeeman background correction. The detection limit was 3.0 pg cadmium, corresponding to 1.0 g/l of cadmium in the concentrated acid. Most of the acids analyzed contained 2–5 g/l of cadmium. The method was checked using electrochemical preconcentration of cadmium, followed by flame atomic absorption spectrometry.     

Determination of trace impurities in electronic grade quartz: Comparison of inductively coupled plasma mass spectroscopy with other analytical techniques

An analytical procedure for the determination of uranium and thorium in the sub-ng/g range as well as of other trace elements in the ng/g to g/g range in high purity quartz samples is described. The results obtained by inductively coupled plasma mass spectroscopy (ICP-MS) are compared to those obtained by other analytical techniques (instrumental neutron activation analysis, INAA; flame atomic absorption spectrometry, AAS; Zeeman graphite furnace atomic absorption spectrometry, ZGFAAS; total reflection X-ray fluorescence analysis, TRFA; direct current arc optical emission spectrometry, DC-arc OES; and X-ray fluorescence analysis, XRFA). For the ICP-MS measurements, the decomposition of the samples is carried out with HF/HNO₃/H₂SO₄-mixtures. The results obtained by the different methods show reasonable agreement. For uranium and thorium, ICP-MS proves to be the most sensitive method: detection limits of about 50 pg/g can be achieved for both elements.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Cover Picture: Metallic Impurities within Residual Catalyst Metallic Nanoparticles Are in Some Cases Responsible for “Electrocatalytic” Effect of Carbon Nanotubes (Chem. Asian J. 4/2009)

At first sight , carbon nanotubes seem to be perfect materials, but appearances can be deceptive. Carbon nanotubes contain impurities and these impurities are often contaminated by yet other impurities. Interestingly, while main impurities (such as Co and Mo) are not electrochemically active, impurities of impurities (such as Fe in this case) dominate the electrochemistry of carbon nanotubes for reduction of important biomarkers, such as hydrogen peroxide. H. Iwai and M. Pumera discuss the importance of this observation in their Full Paper on page 554 ff.

     

Identification of Indigo Dyes in Painting Layers by Pyrolysis Methylation and Silylation. A Case Study: “The Dinner of Emmaus” by G. Preti

Reactive pyrolysis, under methylating or silylating conditions, in combination with gas chromatography-mass spectrometry (GC-MS) was evaluated as an analytical method for the detection of indigo dyes in painting layers. Samples with the addition of tetramethylammonium hydroxide (TMAH) or hexamethyldisilazane (HMDS), for pyrolysis/methylation and pyrolysis/silylation experiments, respectively, were pyrolysed at 600 °C by means of a heated filament pyrolyser and the evolved products were analysed on-line by GC-MS. Methyl and silylated pyrolytic markers, related to 2-aminobenzoic acid and the indoxyl moiety, were established from the analysis of synthetic indigo, neat or as a pigment of artificial painting layers containing a siccative oil. The occurrence of these markers was investigated in a real sample, taken from the painting The dinner of Emmaus by G.Preti (XVII century), in order to identify the blu pigment. Positive identification of indigo was achieved by pyrolysis/silylation and confirmed by RAMAN spectroscopy.     

Determination of arsenic species in marine organisms by HPLC-ICP-OES and HPLC-HG-QFAAS

Separation and quantification of six arsenic species have been performed in cod, tuna and mussel samples by high performance liquid chromatography (HPLC) using inductively coupled plasma-optical emission spectrometry (ICP-OES) and hydride generation-quartz furnace atomic absorption spectrometry (HG-QFAAS) as detection techniques. It has been shown that arsenic extraction with a water-methanol (11) mixture is sufficiently quantitative for the cod and tuna, in which arsenic is mainly present as arsenobetaine (about 90% of total As extracted). In contrast, only 60% of the element is extracted from the mussels and the chromatograms obtained reveal the presence of an unknown compound. Detection limits are in the g ml^–1 range for the HPLC-ICP-OES technique (quantification of arsenobetaine and arsenocholine) and in the ng ml^–1 range for the HPLC-HG-QFAAS system (quantification of arsenite, arsenate, monomethylarsonic and dimethylarsinic acids).     

Direct analysis of thin-layer chromatographic spots of narcotics by means of diffuse reflectance Fourier transform infrared spectroscopy

The technique of diffuse reflectance Fourier transform infrared spectrometry (DRIFT) as an in situ detection method was used for the qualitative and quantitative analysis of drugs (heroin, cocaine and codeine) separated by thin layer chromatography.It was found that at a given interferometer throughput and detector sensitivity the quality of the spectrum depends strongly in the type of the chromatographic thin layer used. A detection limit of approx. 2 g was attained on a microcrystalline cellulose thin layer with a dynamically aligned Bio-Rad Digilab FTS 60A/896 type interferometer and room temperature DTGS detector. A reliable qualitative analysis can be made with as little as 10 to 15 g drug per spot.     

Photometric determination of palladium with the inclusion complex 1,2-Diaminoanthraquinone-β-cyclodextrin as ligand

1,2-Diaminoanthraquinone forms a 11 inclusion complex with-cyclodextrin in aqueous media and at different pH. This can be employed to solubilize the anthraquinone in water for use as a ligand for metal ions. This ligand can be used to determine palladium at trace levels spectrophotometrically. The limit of detection is 11 ng/ml and the R.S.D. is 2.1%. The performance can be improved by using derivative spectrometry.     

Synthesis and structure of supramolecular polyoxothiometalate nanocluster containing 52 metal atoms [{Mo3S4(H2O)5}4(γ-SiW10O36)4]16–

The polyoxothiometalate complex [{Mo₃S₄(H₂O)₅}₄(-SiW₁₀O₃₆)₄]^16– was prepared by the reaction of the cationic triangular molybdenum aqua complex [Mo₃S₄(H₂O)₉]⁴⁺ (electrophile) with the lacunary polyoxotungstate complex [-SiW₁₀O₃₆]^8– (nucleophile). According to the results of single-crystal X-ray diffraction analysis of the dimethylammonium salt, the anionic nanocluster contains 52 molybdenum and tungsten atoms and has a cyclic porphyrin-like structure.     

The pKR+ values for coordinated propargyl cations [Cp2M2(CO)4(μ-η2,η3-HC≡CCR1R2)]+ (M = Mo,W)

The pK_R+ values for metal-stabilized carbocations [Cp₂M₂(CO)₄(-²,³-HCCCR¹R²)]⁺ (M = Mo, W) containing primary (R¹ = R² = H), secondary (R¹ = H, R² = Me), or tertiary (R¹ = R² = Me) coordinated propargyl cations were measured in 50% aqueous acetonitrile. Their stability increases from the tertiary to primary cation, and the stability of the tungsten-containing cations is higher than that of the corresponding molybdenum analogs.