Joint determination of fluorine and chlorine in granitic rocks with ion-selective electrodes

This enables both fluorine and chlorine in granitic rocks to be determined with a single sample. A rapid technique, using fusions in culture tubes, and a slower technique, employing fusions in platinum crucibles are described. The culture-tube technique is suitable for geochemical exploration and employs an oxidizing flux so that sulphide-bearing rocks can be analysed. The platinum-crucible technique yields fluorine and chlorine results for the standard rocks G-2 and GSP-1 that are comparable in value and precision to those obtained by other analytical methods. It is faster, easier to manipulate and yields higher fluorine values than the existing joint spectrophotometric method.     

Differential spectrophotometric determination of silica in rocks as α-molybdosilicic acid in presence of phosphate and other interferences

High concentrations of silica in rocks are determined by means of the stable α-12-molybdosilicic acid formed at around pH 4.2 in acetate buffer. Phosphate interference is avoided by acidification with sulphuric acid. Silica is quantified by differential spectrophotometry at 400 nm against standard rock solutions. Considerable amounts of phosphorus, arsenic and titanium and small amounts of germanium and vanadium do not interfere. The standard deviation is about 0.3%. The method is rapid and suitable for routine analysis of silicate and phosphate rocks.     

The determination of vanadium in geological materials by activation analysis with pre-irradiation separation

Vanadium is determined in silicate rocks by neutron activation after dissolution of the samples with HF/HNO₃ and separation by solvent extraction. The chemical yield of the pre-irradiation separation is determined by means of ⁴⁸V tracer. Results for 15 U.S. Geological Survey standard rocks are presented and discussed in relation to literature data. The method is especially useful at vanadium concentrations below 10 ppm, where purely instrumental neutron activation as well as other techniques commonly used for vanadium determinations in rocks, have inadequate sensitivity.     

Determination of chlorine, bromine and iodine in rock samples by radiochemical neutron activation analysis

Chlorine, bromine and iodine (hereafter, halogens) were detemined for rock samples by radiochemical neutron activation analysis. The powdered samples and reference standards prepared from chemical reagents were simultaneously irradiated for 10 to 30 minutes with or without a cadmium filter in a TRIGA-II reactor at the Institute for Atomic Energy, Rikkyo University. The samples were subjected to radiochemical procedures of halogens immediately after the irradiation. Iodine was firstly precipitated as PdI₂, and chlorine and bromine were successively precipitated as Ag-halides at the same time. In this study, geological standard rocks, sedimentary rocks and meteorites were analyzed for trace halogens. In some Antarctic meteorites, iodine contents were observed to be anomalously high. Chlorine contents also are somewhat high. The overabundance of iodine and chlorine must be caused by terrestrial contamination on the Antarctica.     

Determination of chlorine in silicate rocks by neutron activation analysis

A simple radiochemical neutron activation analysis scheme has been developed for the determination of chlorine in silicate rocks. The method involves a 15-min thermal neutron irradiation of rock powder followed by a quick separation of ³⁸Cl as AgCl, and Ge(Li) spectrometry. Chemical yield, normally ranging between 95% and 100%, is monitored gravimetrically through the recovery of AgCl. The procedure has been tested on several geochemical standards to assess its accuracy and precision. The values obtained for standard rocks agree with the literature values. At the 100-ppm level, the analytical precision for chlorine is within ±5% (2σ).     

A study of the electronic structure of octavinylsilsesquioxane and dendron with chromium based compounds by X-ray photoelectron spectroscopy and quantum chemical modeling in the DFT approximation

The electronic structure and some features of octavinylsilsesquioxane interaction with sulfene chloride chromium acetylacetonate complex were studied by means of XPS and DFT. According to XPS, spectrum lines have close positions for all the studied compounds, half-width for dendrons not exceeding 2 eV. For octavinylsilsesquioxane, the broader lines appear due to the action of substrate atoms. Chemical composition of a dendron was determined by analyzing the concentrations of atoms in different chemical states and a residual content of chlorine atoms. Chemical bonding between the complex and octavinylsilsesquioxane is provided by the covalent interaction of carbon and sulfur atoms.     

硫氰酸汞间接分光光度法测定三乙基铝中氯的含量

建立了测定三乙基铝中氯含量的硫氰酸汞间接分光光度法。在酸性溶液中,硫氰酸汞与氯离子反应后游离出硫氰酸根离子,硫氰酸根离子与铁离子反应生成红色硫氰酸铁络合物,于460 nm波长处测定该络合物的吸光度,从而间接获得氯的含量。对测量过程的波长、酸度、显色剂的用量、显色剂的稳定性等因素进行了探讨。氯的质量在0~50μg范围内与吸光度呈良好的线性关系,线性相关系数r=1.000 0,测定结果的相对标准偏差为0.07%~0.20%(n=6),加标回收率为94.8%~105.0%。该法适用于三乙基铝工业品中氯含量的测定。     

Copper(II) complexes containing chiral substituted 2-(4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-one-2-yl)pyridine ligands: Synthesis, X-ray structural studies and asymmetric catalysis

New chiral N,N-bidentate ligands derived from substituted 2-(4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-one-2-yl)pyridines have been prepared and characterised by means of ¹H, ¹³C NMR spectroscopy and optical rotation. Their Cu(II) complexes were characterized by means of elemental analysis, ¹H NMR spectroscopy and MS. By means of X-ray diffraction, molecular geometry of the complex of 2-(1-methyl-4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-one-2-yl)pyridine with copper(II) chloride was determined. The complex exhibits heterochiral dimeric arrangement of two square pyramids with one terminal and one bridge-forming chlorine atoms and two nitrogen atoms in the bases of the pyramids. The tops of these pyramids are formed by the remaining chlorine atoms. The complexes prepared catalyse the Henry reaction with the overall yields of 41-97% and with the maximum enantioselective excess of 19%.     

Determination of iron in silicate rocks by substoichiometric radioisotope dilution analysis

Iron is determined in rocks by an isotope dilution method involving dissolution with hydro fluoric acid, extraction of iron(III) chloride into isopropyl methyl ketone, stripping with dilute nitric acid, and substoichiometric separation of the Fe-EDTA complex on a cation-exchange column. The precision and accuracy are 1.5% relative or better, as indicated by analyses of some U.S. Geological Survey standard rocks.     

Routine multielement instrumental neutron activation analysis of silicate rocks using short-lived radionuclides

By means of thermal neutron activation and countings on the small planar and large coaxial Ge(Li) detector, 13 elements are determined in various silicate rocks, using short-lived radionuclides with half-lives from 2 min to 15 h. A method of routine analysis with simple dead-time and pile-up correction is described and tested with the standard rocks AGV-1 and G-2.     

Minimizing the effect of organic matrices in the analysis of tin-containing extracts by electrothermal atomic absorption spectrometry: Determination of Tin in rocks

The effect of the nature of the extracted complex and of the organic solvent on the sensitivity of the extraction/atomic absorption determination of tin in a graphite-furnace atomizer is investigated. It is recommended that extracts of tin as its chloride complex, or chelates with N-benzoyl-N-phenylhydroxylamine or 8-quinolinol, in organic solvents which do not contain chlorine should be used. The depressive effect of the organic matrix can be significantly decreased by using ascorbic acid as matrix modifier, by atomization from a graphite platform, and by using an atomizer coated with tungsten carbide. The procedure developed is applied to the determination of tin in rocks. For tin concentrations of 0.1–10 μg g^?1, the relative standard deviation does not exceed 10%.     

Neue verfahren zur jodometrischen mikrobestimmung von jodid- bzw. Bromidion

The methods described above are based on the fact, that iodide can be determined as iodate on iodometric way after oxidation with freshly prepared chlorine water and after removal of excess of free chlorine by means of potassium cyanide. However oxidation may be carried out by adding of hypobromite the excess of which can be removed by adding of phenol water.Bromide can be transformed to BrCl by means of an excess of chlorine water. BrCl reacts with potassium cyanide under formation of cyanogen bromide and chloride. The excess of free chlorine would be removed as cyanogen chlorine and chloride. The cyanogen bromide formed can be measured on the usual iodometric way.     

淋洗液自动发生-离子色谱法测定重整催化剂中氯的含量

建立了重整催化剂中氯含量的淋洗液自动发生-离子色谱测定方法.以4 mL 7.5 mol/L NaOH溶液提取重整催化剂中Cl-,以淋洗液自动发生装置产生的KOH溶液为流动相,进行离子色谱法测定.结果表明,溶液中Cl-线性关系良好,相关系数为0.9999,测定结果的RSD小于0.76%,加标回收率为98.7%～102.8...     

聚氯乙烯结构缺陷和热不稳定性之间关系的研究 2.各种结构缺陷含量和热脱氯化氢速率之间的关系

本工作采用溴加成法、酚解法、FTIR法及臭氧裂解法分别测定了五种不饱和蒸气压下聚合的PVC样品(u-PVC)和五种商品PVC样品(s-PVC)的总双键、总不稳定氯、孤立双键和内部双键的含量.通过研究结构缺陷和PVC的平均分子量及脱HCl速率的相互关系,揭示了不饱和总双键值,总不稳定氯和孤立双键含量彼此的相关性是建立在它们分别与1/M_n的相关性基础之上,从而得出了这三种定量值测得的主要都是端基烯丙基氯结构.根据三者对脱HCl速率的良好线性相关性,首次提出了端基烯丙基氯结构在HCl催化作用下异构化成内部烯丙基氯从而成为脱HCl速率主要原因的机理.     

Theoretical Studies on the Molecular Structures and Thermodynamic Properties of Polychlorinated Fluorenes

Geometric structures of 135 polychlorinated fluorene (PCFR) molecules were optimized using density functional theory (DFT) at the B3LYP/6-311G** level and their thermodynamic properties in the ideal gas state were calculated. The relations of these thermodynamic properties with the number and position of chlorine atoms were also explored, from which the relative stability of PCFR congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation (Δr,fGθ). The results show that the geometric configuration of PCFR isomers is determined by the position of chlorine atoms. There exist two types of intramolecular weak interactions, i.e., C-H···Cl and Cl···Cl interactions in PCFR molecules. The change of ΔfHθ and ΔfGθ of most stable PCFR isomers with increasing the number of chlorine atoms is different from that in most unstable PCFR congeners. The values of ΔfHθ and ΔfGθ for PCFR isomers with the same number of chlorine atoms strongly depend on the position of chlorine atoms and the relative stability of PCFR congeners is mainly determined by intramolecular delocalized π bond and Cl···Cl nuclear repulsive interaction.     

Determination of lead in rocks by radiometric isotope dilution and substoichiometric extraction

A rapid procedure is described for the determination of lead in rocks by an isotope-dilution substoichiometric method. After the sample has been digested with acid in the presence of ²¹⁰Pb tracer, the lead is separated by dithizone extractions. After the lead has been back-extracted into aqueous solution, it is reacted with a substoichiometric amount of EDTA. Excess of unreacted lead is removed by extraction with dithizone in carbon tetrachloride, and the specific activity of the aqueous complex is determined by counting ²¹⁰Pb. The standard deviation of the method is less than 10 % for replicate determinations of lead in several U.S. Geological Survey standard rocks. The agreement with literature values indicates that the method is accurate.     

Pneumatoamperometric determination of chlorine in water

Free chlorine in water can be determined by acidifying the water sample, purging it with nitrogen and determining the chlorine present in the nitrogen stream with a gold porous electrode. The current response of gold porous electrode is related to the concentration of free chlorine by using a calibration curve. This pneumatoamperometric method gives results fully comparable to the standard o-toluidine photometric method used for water supplies. It is uninfluenced by the presence of other dissolved oxidants and requires only one milliliter of sample.     

火焰原子吸收光谱法间接测定非金属材料中氯

报道了火焰原子吸收光谱法（ＦＡＡＳ）间接测定非金属材料中氯的方法，采用ＡｇＣｌ沉淀，测定剩余Ａｇ~＋间接求出氯含量。方法的特征浓度为０．０１４ｍｇ／Ｌ（１％吸收），检出限为０．０３２ｍｇ／Ｌ（３），测定下限为０．１１ｍｇ／Ｌ，相对标准偏差（ＲＳＤ）为１．５％～１０％，样品加标准回收率在９１．４％－１０５％之间。     

Determination of chlorine distribution in silicon dioxide by neutron activation

A neutron activation method for the determination of chlorine distribution in silicon dioxide on the surface of Si wafers has been developed. After irradiation of the sample with a standard, successive layers are removed from the oxide surface by chemical etching and the chlorine content in the solutions obtained is determined gamma-spectrometrically. Using a Ge(Li) detector, a lower limit of determination of 1.0·10⁻⁷ g was obtained. This limit can be improved by using a NaI(Tl) detector. The error of chlorine determination is discussed.     

Boron and chlorine concentration of volcanic rocks: An application of prompt gamma activation analysis

Summary Boron and chlorine concentrations in geological standards and in representative volcanic rock samples were determined by prompt gamma activation analysis (PGAA). The results of the GSJ standard measurements proved the high precision of PGAA in measuring the boron, chlorine, other trace elements (Sc, Nd, Sm, and Gd) and the major element contents of the samples. The rock samples originate from the western part of the Northern-Pannonian Volcanic Field (NPVF), which includes the Central Slovakian Volcanic Field (CSVF), the Börzsöny and the Visegrád Mts. (VMt.). The oldest 16-13.5 Ma samples as the first products of the Miocene calc-alkaline volcanism are the most enriched in B (11-29 µg/g), whereas the primitive basaltic andesites (from CSVF), the latest products (9 Ma) of the volcanic activity have lower B content (8-9 µg/g). The measured B concentrations correlate positively with fluid-mobile elements, and the trace element pattern of the samples show subduction related signatures. The chlorine content of the investigated samples shows wide variation between 42.62 and 1148.45 µg/g. The 9 Ma samples from the CSVF show Cl contents between 150-160 µg/g. In agreement with the latest geodynamic models of the Neogene calc-alkaline volcanism^1,2 in the NPVF during the shallow, prograding subduction, the fluid-mobile elements metasomatized the mantle wedge. Thus the oldest volcanic rocks have relatively higher B (>11 µg/g) and high but variable Cl contents. As the subduction waned and extension proceeded, the magma generation region changed to a not thoroughly metasomatized mantle by the former subduction event, resulting in lower B, low and stable Cl content of the younger (9 Ma) volcanic rocks.