A scheme for the analysis of monazite and monazite concentrates

A scheme using ion-exchange methods is described for the analysis of monazites and monazite concentrates. The sample is opened up with concentrated sulphuric acid, and the resultant solution is applied to a column of Zeocarb 225 resin. After phosphate has been washed out, lead, aluminium, titanium, iron, uranium, calcium and magnesium are eluted with N hydrochloric acid and determined by specific, mainly spectrophotometric, methods. Rare earth elements are eluted with 3 N hydrochloric acid. Cerium is separated from the other rare earths by solvent extraction of its nitrate with methyl iso-butyl ketone; both groups are determined gravimetrically. Thorium is eluted from the ion-exchange resin with 3.6 N sulphuric acid and determined spectrophotometrically with thorin.The sulphuric acid-insoluble minerals are brought into solution by a double fusion method, and the determinations are carried out by a combination of ion-exchange and photometric procedures. Silica, phosphorus pentoxide, tin and chromium are determined by photometric methods, using separate portions of the sample.Lanthanum, yttrium and ytterbium are determined in a 1 M perchloric acid solution of the mixed rare earth oxides (less cerium) using flame photometry. Samarium, praseodymium and neodymium are determined by spectrophotometry.     

Thermomicroscopic and ultraviolet spectrophotometric identification of steroid hormones

Thermomicroscopic data (melting points or intervals, eutectic temperatures, refractive indices of the melts) have been determined for 70 steroid hormones and are tabulated in order of increasing melting temperature. Ultraviolet absorption data, specially determined or taken from the literature, are given in place of refractive index data when the latter could not be determined accurately because of decomposition.     

Spectrophotometric determination of formaldehyde,furfural, and vanillin in bisulfite solutions

Formaldehyde, furfural, and vanillin are determined in solutions containing bisulfite. The interference of bisulfite is eliminated by oxidation with iodine before furfural and vanillin are determined spectrophotometrically in ultraviolet light. Formaldehyde is determined with chromotropic acid by a slightly modified procedure; bisulfite is not destroyed previously.     

Relationship between the spectral properties of solutions of borofluoride complex of alkylated dipyrromethene and the physicochemical parameters of solvents

Spectral and photophysical characteristics of borofluoride complex of alkylated dipyrromethene (Bodipy) are determined by means of absorption and fluorescence electron spectroscopy in various organic solvents. Dependences of the spectral and photophysical characteristics of Bodipy solutions vs. the physico-chemical parameters of solvents are obtained by linear regression analysis and the contribution from each parameter to the property under study is determined. It is established that the negative solvatochromic effect is intrinsic for Bodipy. It is concluded that specific interactions contribute substantially to the properties of the chromophore, which are determined by the electron donor properties of the solvent.     

电感耦合等离子体发射光谱(ICP-OES)法同时测定矿泉水界限指标中的4种元素

国家标准方法中,对矿泉水界限指标中的四种矿物质元素锌、锂、锶、偏硅酸(以H2SiO3计),需每种元素分别测定且步骤繁琐,采用电感耦合等离子体发射光谱(ICP-OES)法对矿泉水中这4种元素的含量进行同时测定,四种元素的检出限在0.01～0.10 mg/L,对市售矿泉水进行了检测,加标回收率在83％ ～100％,相对标准...     

The use of neutron activation for routine analysis of pure iron and chromium

A method is presented for the routine analysis of high-purity iron and chromium by neutron activation analysis. The impurities determined are those which are significant in the control of the purification processes. Nine elements are determined in iron without separation; Co, Cr and Mo can also be determined after an anion-exchange separation. In chromium, a single elution on an anion exchanger allows the detection of nine significant impurities. For the determination of nickel a special method is used. All these methods were chosen to obtain the most comprehensive analytical procedure at the lowest cost.     

On the determination of desorption temperatures in field desorption mass spectrometry

The field desorption temperatures of some compounds are determined by indirect heating of the emitters. The temperatures thus obtained are lower, compared with those determined by other authors. The reasons for this deviation are discussed.     

The determination of small quantities of metal ions using anthranilic acid

Metal ions which form insoluble anthranilates may, if present singly, be determined by dissolving the anthranilate in acid and titrating the liberated anthianilic acid with perchloratocerate. Or preferably the anthranilic acid may be determined absorptiometrically with N-(1-naphthyl) ethylenediamine hydrochloride after diazotisation. Under the conditions described quantities of the order of 1–5 micromoles of metal are conveniently determined by the volumetric method and one fifth of such amounts by absorptiometry. With the latter the use of larger Spekker cells would increase the sensitivity of the method.By making use of the insolubility of its complex in acetate buffers copper may be determined in the presence of other metals if these are not in excessive amounts. Various other determinations. are also possible.Attempts to use the fluorescence of the liberated anthranilic acid have indicated the method to be less satisfactory than absorptiometry.     

Skeletal deformation vibrations and rotational isomerism of methylbutenes and methylpentenes as model compounds of 1,4-polyisoprene

Infrared spectra of methylbutenes and methylpentenes in the skeletal deformation region have been measured. The force constants for the skeletal deformation vibrations are determined from the frequencies of isobutylene, isobutylene-d₆, and methylbutenes. The frequencies of methylpentenes are calculated for the various conformations, and the stable rotational isomers determined. The energy differences between the isomers are determined from the temperature dependence of the spectra. These results are correlated with the conformations of cis-and trans-1,4-polyisoprene chains, and possible conformations are suggested.     

Method for increasing the accuracy of the determination of elemental impurities in metals by spark source mass spectrometry

This paper presents a method for increasing the accuracy in the determination of impurities in metals by spark source mass spectrometry (SSMS). The method is based on the application of a parametric equation to calculate sensitivity coefficients. The parameters of this equation are determined from results obtained by analysis of an appropriate standard material. Concentrations in the sample of elements certified in the standard material are determined using experimental values of sensitivity coefficients, while the concentrations of remaining elements in the test sample are determined using coefficients calculated from the proposed parametric equation.     

Investigation of separation and identification possibilities of some metal-DEDTC complexes by sequential TLC-IR system

The separation and identification possibilities of some metal-diethyldithiocarbamate (DEDTC) complexes are investigated by thin-layer chromatography-IR sequential system. DEDTC complexes of metal cations are prepared in a predetermined optimum pH or pH range. Optimum separation conditions of these complexes and the reproducibilities of their retention factor (Rf) values are investigated on a series of precoated or laboratory-made TLC plates. Rf values are determined using the one-dimensional ascending technique. The precision of the procedures is determined for five replicates in terms of standard deviation. Detection limits are also determined for each of the metal complexes. The IR spectra are scanned and interpreted for their precise identifications after preconcentration with a wick-stick procedure for the complexes, giving the overlapped Rf values. The complexes could be identified by the aid of IR absorption bands. It has been determined that these IR absorption bands can also be used as reference spectral bands in possible quantitative studies. It is concluded that an efficient and successful qualitative analysis is possible for incompletely-separated complex compounds using an IR spectrophotometer as the TLC detector.     

Study of viscometric properties of L-ascorbic acid in binary aqueous mixtures of D-glucose and D-fructose

The relative viscosities and activation parameters of L-ascorbic acid have been determined in water and binary aqueous mixtures of D-glucose and D-fructose at different temperatures. A and B-coefficients of Jones–Dole equation are determined using density and viscosity data. Gibbs energy of activation of viscous flow per mole of solvent as well as per mole of solute along with activation enthalpy and entropy is also determined using Feakin’s transition-state theory. The obtained results are explained in terms of intermolecular interactions and in this study L-ascorbic acid has been found as structure breaker in binary aqueous mixtures of D-glucose and D-fructose.     

The elaboration of technology of preparation of adsorption ion exchange materials in the basis of rice waste

The results of investigations of agricultural waste (rice husk) processing are presented. The kinetics of processing of cellulose and cation-exchange material, having high exchange capacity is determined, and the technology of its production is proposed. The influence of the temperature, esterification time, and the volume of phosphorus acid on exchange capacities of produced sorption materials are determined.     

Indirect atomic absorption spectrometric determination of mixtures of chloride and iodide by precipitation in an unsegmented flow system

Chloride and iodide are injected into a carrier silver nitrate and the precipitates formed are retained on a stainless-steel filter, so that total chloride and iodide can be determined by the decrease in the atomic absorption signal for silver. The silver chloride precipitate is subsequently dissolved with ammonia and chloride only is determined. Iodide is determined by difference. Mixtures of these anions at μg ml^?1 levels can be determined for chloride/iodide ratios from 7.5:1 to 1:60, with a sampling frequency of ca. 10 h^?1. Applications to the determination of chloride in foodstuffs and wines are described. Up to 10 samples per hour can be handled and 50–100 samples can be run before the filter must be cleaned.     

气相色谱-质谱法分析研究野生菱角壳中多糖化合物的单糖组成

采用乙醇分级沉淀法，首次从野生菱角壳中提取出4种多糖化合物，利用气相色谱-质谱法，确定了菱角多糖分别由阿拉伯糖，鼠李糖，木糖，甘露糖，半乳糖，葡萄糖，乳糖和蜜二糖组成，其中以葡萄糖，半乳糖，甘露糖和木糖为主。     

Phase behavior of elemental aluminum using monte carlo simulations

Monte Carlo simulations are presented for two models of aluminum: an embedded-atom model and an explicit many-body model. Vapor/liquid coexistence curves are determined using Gibbs ensemble Monte Carlo simulations. The normal boiling points predicted by both models are somewhat higher (by about 10%) than the experimental value. Isothermal constant-stress simulations are used to simulate solid Al from 300 K to the triple point. The solid structures are at least metastable in the face-centered cubic configuration, and the specific heat is determined to be lower than the experimental value. The melting point for the embedded-atom model determined via thermodynamic integration along a pseudo-supercritical path is approximately 20% higher than the experimental value.     

Structural aspects of host molecules acting as ionophores in ion-selective electrodes

Structural aspects of ligand molecules acting as neutral ionophores in ion-selective membrane electrodes are discussed and examples of Li-selective ionophores are presented. The relationship between the structure of ionophore and its complex determined by X-ray and NMR study and the selectivity of ISE was determined.     

Intermolecular association of Tilan with vinylpyrrolidone copolymers

The results of physicochemical studies of promising prolonging agents for Tilan antibiotic: polyvinylpyrrolidone and vinylpyrrolidone copolymers, are reported. The optimal component ratios of the drug formulation were determined by viscometry and conductometric titration. As determined by IR spectroscopy, the components are associated mainly via intermolecular hydrogen bonds.     

基体辅助激光解吸电离飞行时间质谱法测定钙调素的分子量

近几年来，由于各种“软”电离技术的发展和应用「‘，’‘，为利用质谱分析生物大分子提供了一条十分有效的途径［‘j，其中基体辅助激光解吸电离飞行时间质谱法（MALDI－TOF－MS）是最有前途的技术之一D‘．钙调素（CaM）是动植物中普遍存在的多功能的胞内钙受体蛋白，参与调控许多生理反应［”．最近几年也在细胞外区域发现了钙调素及其功能［”．钙调素分子量的准确、快速测定是钙调素性质、结构和功能研究的首要问题．目前CaM分子量的测定大多采用SDS－PAGE、凝胶过滤和沉淀平衡等方法，例如对牛脑CaM分子量的SDS－PAGE测…     

ICP-OES同时测定矿泉水界限指标中的4种元素

矿泉水界限指标中的四种矿物质元素锌、锂、锶、偏硅酸(以H₂SiO₃计),国标方法需每种元素分别测定且步骤繁琐,本实验采用ICP-OES对矿泉水中这4种元素的含量进行同时测定,四种元素的检出限在0.01~0.10 mg/L,对市售矿泉水进行了检测,加标回收率在83 %~100 %,相对标准偏差为0.31 %~1.96 %,方法简便省时,精密度和准确度较高,可以作为一种鉴别矿泉水品质的方法。