工业硫磺中As,Se的测定

本文研究了工业硫磺试样的溶解和试样中砷和硒的测定方法。经典方法系采用溴 四氯化碳溶解样品 ,试剂用量大、操作繁杂、污染环境 ,且导致微量砷、硒损失。本文提出用 1mLHNO3 +1mLHClO4 溶解硫磺试样 ,试剂用量少 ,在控温电热板上处理样品操作简单 ,砷、硒无损失。在盐酸介质中 ,用HG ICP AES法一次取样依次测定砷、硒。方法检出限分别为 0 6和 0 7ng·mL-1,方法的RSD(n =8)分别为 2 1%和 1 9% ,加标回收率分别为 99 6 %和 10 1%。     

Kinetic determination of cysteine and thiosulphate by inhibition of Hg(II) catalyzed ligand substitution reaction

The sulphur containing inhibitors (I), cysteine (Cys) and sodium thiosulphate (THS), have been found to inhibit Hg(II) catalyzed exchange of cyanide in hexacyanoferrate(II) by nitroso-R-salt (NRS). The inhibitory effect of both the ligands are attributed to their binding tendencies with Hg(II) leading to the formation of catalyst-inhibitor (C-I) complex. The reactions have been followed spectrophotometrically in aqueous medium at 720 nm by noting the increase in absorbance of the green colour product, [Fe(CN)₅NRS]³⁻ at pH 6.50 ± 0.02, temp 25.0 ± 0.1 °C and ionic strength (μ) 0.1 M (KNO₃). A most plausible mechanistic scheme involving the role of analytes (inhibitors) has been proposed. The values of equilibrium constants for complex formation between catalyst-inhibitor (K_CI), catalyst-substrate (K_S) and Mechaelis-Menton constant (K_m) have been computed from the kinetic data. The linear calibration curves have been established between absorbance and inhibitor concentrations under specified conditions. Cys and THS have been determined in the range 1-5 × 10^− 7 M and 4.9-16.9 × 10^− 7 M respectively. The detection limits have been computed to be 1 × 10^− 7 M and 4.9 × 10^− 7 M for Cys and THS, respectively.     

Sulphur and Oxygen Isotopic Composition of Sulphates in Springs Feeding the Wieprz River and Other Springs of Lublin Upland and Roztocze

Abstract

Springs on Roztocze and Lublin Upland have been studied. Isotopic data are compared with data of chemical analyses. The results of studies allow us to distinguish five types of groundwaters. The differentiation is based upon different lithology; opokas, gaizes, sandy-silty-clay deposits, sands with shell sandstones, marly opokas, marly limestones and soft limestones of chalk type. A correlation can be observed between δ³⁴S and the concentration of Ca or Mg ions also a correlation between HCO₃ ^? ion concentration and δ¹⁸O in sulphates. Probably these correlations are the result of some simultaneous processes, which occur in groundwater. The seasonal variations of the isotopic composition and sulphate concentration were observed in four springs feeding the upper Wieprz. The variations were simultaneous and often similar in these springs. Probably, these variations are caused by the admixture of sulphates coming from shallow water layers (or leached from soil); however the variations of the groundwater level may also change chemical and isotopic composition in groundwater.     

A practical method for the determination of sulphur in coal samples by high-resolution continuum source flame atomic absorption spectrometry

Sulphur in coal was determined using a high-resolution continuum source flame atomic absorption spectrophotometer (HR-CS-FAAS) with actylene/air flame. The C-S absorption band at 258.056 nm was found the most suitable analytical line with respect to sensitivity and spectral interferences. The instrumental parameters were optimized. The coal samples were dried and dissolved using microwave-assisted digestion technique. The validity of the method was tested using standard reference material and certified values were found in the limits of 95% confidence level. Since the concentrations of matrix elements of coal other than carbon are low enough not to cause any spectral interferences, the linear calibration method was applied in all quantifications without any problem. The calibration standards were prepared in sulphuric acid. The method was accurate, fast, simple and sensitive. The limit of detection (LOD, 3δ, N = 10) and the limit of quantification (LOQ, 10δ, N = 10) were found to be 0.01 and 0.03% (w/w), respectively. The sulphur concentrations of various kinds of the coal samples received around Turkey were determined. The sulphur contents of the coal samples were ranged from ≤LOQ to 1.2%.     

Solubility of sulphur dioxide in aqueous electrolyte solutions at higher ionic strengths—Chloride and bromide containing systems

The absorption of sulphur dioxide in chloride and bromide containing electrolyte solutions was measured up to ionic strengths of 5 mol/dm³. The thermodynamic equilibrium of the gas phase and the liquid phase was characterized by UV spectroscopy. UV spectra analysis gave strong evidence for SO₂X⁻ complexes existing in the solutions. Consequently, these compounds were implemented in the reaction scheme for absorption.     

近红外光谱结合偏最小二乘判别对硫熏浙贝母的无损鉴别

浙贝母(Fritillariae thunbergii Bulbus)是一种常用的化痰止咳中药,为浙江著名的“浙八味”之一。硫熏能够使浙贝母增白、防虫蛀以及延长保质期,然而过度的硫熏不仅会影响浙贝母的品质,还会危害人体健康。因此,进行硫熏浙贝母的无损鉴别分析有利于浙贝母的品质监测,保障中药质量。采用近红外光谱结合化学计量学方法进行六种不同硫熏程度浙贝母的鉴别分析,在近红外(900～1 700 nm)光谱条件下,采用“boxplot”统计分析1 000～1 100 nm内样本间的光谱反射值的差异。同时采用主成分分析(PCA)进行六种样本的聚类分析。应用连续投影法(SPA)进行数据挖掘获得10条特征波段,建立其偏最小二乘判别分析(PLS-DA)模型。结果表明,建立的PLS-DA模型可达到与全谱类似的判别结果。近红外光谱技术结合化学计量学方法能够实现不同硫熏程度浙贝母的无损鉴别分析,这为后续进行硫熏浙贝母品质分析以及研发相应贝母便携检测仪提供参考。     

Modification of anode surface in organic light-emitting diodes by chalcogenes

Influence of thin chalcogen X (S, Se, Te) interlayer between anode (indium-tin oxide, ITO) and a layer of N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD) used as a hole-transport layer (HTL) on the operating characteristics of organic light-emitting diodes (OLEDs) of composition ITO/X/TPD/Alq₃/Yb (Alq₃ - aluminum 8-quinolinolate) has been investigated. It was found that the sulphur layer decreases operating voltage and enhances operating stability of a device while the selenium or tellurium interlayers impair these characteristics.     

Critical appraisal of the flame photometric detector in petroleum analysis

Summary This paper summarises experience gained at the British Petroleum Limited Research Centre, Sunbury-on-Thames, with sulphur selective gas chromatography (GC) detectors. A single flame photometric detector (SFPD) has been in use for three years for research and routine applications. Three areas of interest are described demonstrating in turn different characteristics of the detector. Firstly, a determination of trace levels of individual organo-sulphur compounds in the 15–65°C cut of crude oils illustrates the complexity of using an SFPD in a rigorously quantitative manner. Secondly, the use of an SFPD as a qualitative tool for the comparison of the sulphur distribution of crude oils up to the temperature limit of GC is cited. Finally, a third section describes the properties of a dual flame photometric detector (DFPD) which are compared and contrasted with those of the SFPD.     

Application of wet chemistry techniques to process analysis and control

The availability of reliable and rugged automatic titrators, flow-injection analysers and ion chromatographs provides opportunities for their application in industrial process analysis. The control of industrial processes such as the removal of sulphur during gas treatment presents a challenge as accurate on-line and in-line analysers are required. The application of automatic titrators and ion chromatographs to the compositional analysis of caustic and alkanolamine gas sweetening solutions is described. Comparisons with other techniques such as flow-injection analysis and ultraviolet and near-infrared spectrometry are made and the pertinent features and benefits of each are discussed.     

流动注射气体扩散技术测定水中微量硫离子的研究

本文提出了一个用气体扩散膜来消除干扰的流动注射光度分析法来测定水样中微量的S~(2-)。该法的检出限为0.25μg/ml S~(2-),工作曲线的线性范围为0.25～25μg/ml S~(2-),对15μg/ml S~(2-)样品10次测定的相对标准偏差<1％,1h能测定20个样品。用本法测定了几种水样中的S~(2-)含量,回收率达96％～102％。