X射线荧光光谱法测定黏土中的主次组分

采用熔融玻璃片制样,选用标准样品,以经验α系数和散射线内标法校正元素谱线重叠干扰和基体效应,使用ZSX Primus Ⅱ X射线荧光光谱仪对黏土样品中的Al₂O₃、SiO₂、Fe₂O₃、CaO、MgO、K₂O、Na₂O、MnO、P₂O₅、TiO₂、Cu、Cr等组分进行测定,分析结果与标准值和化学值相吻合,12次测定的相对标准偏差小于10%.     

熔融制样-X射线荧光光谱法测定铬铁矿中铬、铁、硫等10种主次量组分

采用混合熔剂、熔融玻璃片制样,以适量的NH₄NO₃为氧化剂、Li₂CO₃为保护剂,有效抑制了硫元素的挥发. 使用ZSX Primus ⅡX射线荧光光谱仪测试了铬铁矿样品中的主量组分(Cr₂O₃、TFe)及8个次量组分(SiO₂、CaO、MgO、Al₂O₃、TiO₂、P₂O₅、MnO、S). 方法快速、简便、准确. 用标准物质试样和不同方法进行验证,分析结果与标准值和化学值相吻合,可有效应用于实际科研与生产工作.     

熔融制样-X射线荧光光谱法测定锆钛矿中主次成分

为准确测定锆、钛及其共伴生有用有害杂质元素含量,采用稀释比1∶20的四硼酸锂-偏硼酸锂混合熔剂,先将样品700℃预氧化7 min,再1 050℃熔融19 min制样,建立了熔融制样-X射线荧光光谱法测定锆钛矿中SiO₂、Al₂O₃、Fe₂O₃、CaO、MgO、MnO、TiO₂、K₂O、Na₂O、P₂O₅、ZrO₂等11种主次成分的分析方法。采用标准样品加入光谱纯的方式配制锆钛矿的标准系列样品解决锆钛矿石标准样品不足的问题。结果表明,各组分的检出限在0.004%～0.13%,各组分测定结果的相对标准偏差(RSD,n=12)在0.060%～2.6%。对实际样品进行测定,测定值与传统方法测定值一致,并具有操作简便,分析周期短的优点,解决了锆钛矿石前处理过程中锆钛易水解,分析周期长的问题,对综合评价锆钛矿资源具有重要意义。     

(4-苯硫基-苯基)二苯基硫鎓六氟磷酸盐的合成研究

以P₂O₅为脱水剂,甲烷磺酸为溶剂,二苯亚砜与二苯硫醚反应制备了(4-苯硫基-苯基)二苯基硫六氟磷酸盐.对产物进行了元素分析、紫外光谱、红外光谱、气-质联用和核磁共振的结构确证.该硫盐对环氧树脂具有良好的固化性能.     

钒取代的Dawson型磷钼酸对酪氨酸酶的抑制作用

采用酶动力学方法研究了5种钒取代的Dawson型磷钼酸H₇[P₂Mo₁₇VO₆₂]、H₈[P₂Mo₁₆V₂O₆₂]、H₉[P₂Mo₁₅V₃O₆₂]、H₈[P₂Mo₁₄V₄O₆₂H₂]和H₉[P₂Mo₁₃V₅O₆₂H₂](分别简写为P₂Mo₁₇V、P₂Mo₁₆V₂、P₂Mo₁₅V₃、P₂Mo₁₄V₄和P₂Mo₁₃V₅)对蘑菇酪氨酸酶二酚酶的抑制作用,结果表明,效应物P₂Mo₁₇V、P₂Mo₁₆V₂和P₂Mo₁₅V₃能够明显地抑制酪氨酸酶的活性,其半抑制浓度(IC₅₀)值分别为0.409、0.386和0.386 mmol/L,且均表现为可逆的竞争型抑制,效应物P₂Mo₁₇V、P₂Mo₁₆V₂和P₂Mo₁₅V₃对游离酶的抑制常数K_I分别为0.234、0.391和0.249 mmol/L。 而效应物P₂Mo₁₄V₄在0~1.0 mmol/L浓度范围内,对酪氨酸酶二酚酶无明显抑制作用,效应物P₂Mo₁₃V₅对酪氨酸酶二酚酶表现为激活作用。     

Dawson结构杂多阴离子(P2M18O62)6-(M=Mo,W)的电子结构和催化性质的理论研究

用第一原理密度泛函理论的离散变分方法(DFT-DVM)计算典型的Dawson结构杂多阴离子(P₂M₁₈O₆₂)^6-(M=Mo,W)的电子结构,比较两者之间的差异。结果表明,Dawson结构中极位和赤道位的原子有不同的化学行为,还原电子将主要进入赤道位的金属原子。(P₂Mo₈O₆₂)^6-的反应活性中心主要是配位金属原子Mo、极位桥氧O_pb、赤道位端氧O_et和赤道位中心氧O_ei;(P₂W₁₈O₆₂)^6-的反应活性中心主要是配位金属原子W、极位桥氧O_pb、赤道位端氧O_et.(P₂Mo₈O₆₂)^6-的氧化性强于(P₂W₁₈O₆₂)^6-,而酸性则与此相反。这与Keggin结构(PM₁₂O₄₀)^3-杂多阴离子的情况相同。     

高锰酸钾溶液标准物质的研制

介绍高猛酸钾溶液标准物质的研制过程。对研制的溶液标准物质进行了均匀性和稳定性考察。结果表明,该标准物质均匀性良好,定值稳定期为6个月。用称量滴定法定值,定值结果为c(1/5 KMnO4)=0.100 7 mol/kg(k=2)。该标准溶液满足二级标准物质的技术要求,已被批准为国家级二级标准物质。     

具有Dawson结构的钼钒磷杂多酸氧化还原性质的研究

通过SnCl₂电位滴定、极谱和循环伏安方法,详细研究了2:18系列钼钒磷杂多酸H_(6+n)[P₂Mo^13-nV_nO₆₂]·xH₂O(n=1～3)和H^_4+n[P₂Mo_18-nV_nO₆₂H₂]·xH₂O(n=4,5)在溶液中的氧化还原性质,证实它们的还原为三步分别加合n,2,2个电子,同时加合n,2,2个质子的过程,总结了循环伏安峰电位与pH的关系,提出了还原机理。     

Ti/RuO2-IrO2-SnO2-Sb2O5阳极在农村饮用水消毒中的应用

采用热分解法制备了一种新型高效析氯阳极Ti/RuO₂-IrO₂-SnO₂-Sb₂O₅,将其应用于农村饮用水消毒频繁停开、低电解液浓度的特殊工况下,并与Ti/RuO₂-SnO₂-Sb₂O₅、Ti/RuO₂-TiO₂、Ti/RuO₂-TiO₂-IrO₂三种析氯阳极进行性能对比。通过SEM、EDS、XRD等方法表征测试阳极表面形貌、元素及组成,考察了氯化钠浓度、电流密度、停开频率对阳极析氯效果和寿命的影响。研究发现,Ti/RuO₂-IrO₂-SnO₂-Sb₂O₅阳极活性强、稳定性高;阳极涂层各组分高度融合为固溶体,结构致密,稳定性强;在15 g·L^-1 NaCl、400 A·m^-2电流密度、20℃条件下,Ti/RuO₂-IrO₂-SnO₂-Sb₂O₅阳极电解的电流效率达到91.55%;频繁停开、强化电解条件下寿命达到231 h,是Ti/RuO₂-TiO₂阳极的77倍,预估在400 A·m^-2电流密度下能够使用20年。     

银精矿成分分析系列标准物质研制

研制了系列银精矿标准物质。从日常检验样品中收集了15个不同含量的银精矿样品，每个样品收集5～8个批次，根据预留样品各元素成分含量综合考量后，筛选出4个不同品位的银精矿质控样品作为标准物质候选物，对标准物质候选物进行破碎、筛分、混匀及缩分，然后进行均匀性检验、稳定性进行检验，再由6家权威实验室进行协作定值，并对不确定度进行评定。结果表明，所研制的银精矿标准物质具有良好的均匀性和稳定性。该系列银精矿标准物质共定值6种元素，包括Pb(15%～56.99%)、Au(0.22～1.59 g/t)、Ag(2 913.6～4 855.0 g/t)、Cu(0.21%～1.16%)、As(0.12%～1.87%)、Zn(3.33%～10.58%)，制备过程及定值结果符合国家一级标准物质的规定。     

Charged particle activation analysis of phosphorus in biological materials

Charged particle activation analysis of phosphorus in biological materials using the³¹P (α,n)^34mCl reaction has been studied. Since^34mCl is also produced by the³²S (α,pn) and the³⁵Cl (α, α′ n) reactions, the thick-target yield curves on phosphorus, sulfur and chlorine were determined in order to choose the optimum irradiation conditions. As a result, it was found that the activation analysis for phosphorus without interferences from surfur and chlorine is possible by bombarding with less than 17 MeV alphas. The applicability of this method to biological samples was then examined by irradiating several standard reference materals. It was confirmed that phosphorus can readily be determined at the detection limit of 1 μg free from interferences due to the matrix elements.     

Fluorine and chlorine doping in oxygen-deficient perovskites: A strategy for improving chemical stability

The present work describes the effect of fluorine and chlorine doping on the chemical stability of proton conductors Ba₂In₂O₅, Ba₄In₂Zr₂O₁₁, and Ba₄Ca₂Nb₂O₁₁ against carbon dioxide and water steam. It was proved that both undoped and halide-doped compositions demonstrate good chemical stability under H₂O treatment without degradation and without any hydrolytic decomposition. The hydration process leads to the change in the crystal structure only. The treatment in the CO₂/air (1:1) atmosphere (500 °C, 10 h) leads to the decomposition of undoped samples only. Halide-doped samples retain their structure without detectable products, that is, they are more chemically stable compared with undoped compositions. The method of halide doping can be used as the promising technique for obtaining the new perovskite-related materials with high level of chemical stability.     

Ammoxidation of methylpyrazine over phosphorus-modified vanadium-titanium catalysts

Vanadium-titanium catalysts modified with phosphorus additives (1-15 wt.% of P₂O₅) have been studied in methylpyrazine ammoxidation. Introduction of high amounts of the additive (≥ 10 wt.% of P₂O₅) results in a decrease in activity and selectivity of the catalysts due to formation of low active phase - a ternary compound with the component ratio V : P : Ti ≈ 1 : 1 : 1 with only one type of slightly distorted tetrahedral vanadium (5+) bound via oxygen to phosphorus (5+). The nature of the active sites of the samples modified with 1-5 wt.% of P₂O₅, similarly to that in the V-Ti-O catalyst, was found to include the V⁵⁺ cations strongly bound with TiO₂ and located in the significantly distorted octahedral oxygen environment. This revised version was published online in June 2006 with corrections to the Cover Date.     

Chemical analysis of sulfur species in geothermal waters

Analytical methods have been developed to determine sulfur species concentrations in natural geothermal waters using Reagent-Free™ Ion Chromatography (RF™-IC), titrations and spectrophotometry. The sulfur species include SO₄²⁻, S₂O₃²⁻, and ∑S²⁻ with additional determination of SO₃²⁻ and S_xO₆²⁻ that remains somewhat semiquantitative. The observed workable limits of detections were ≤0.5 μM depending on sample matrix and the analytical detection limits were 0.1 μM. Due to changes in sulfur species concentrations upon storage, on-site analyses of natural water samples were preferred. Alternatively, the samples may be stabilized on resin for later elution and analysis in the laboratory. The analytical method further allowed simultaneous determination of other anions including F⁻, Cl⁻, dissolved inorganic carbon (DIC) and NO₃⁻ without sample preservation or stabilization. The power of the newly developed methods relies in routine analysis of sulfur speciation of importance in natural waters using techniques and facilities available in most laboratories doing water sample analysis. The new methods were successfully applied for the determination of sulfur species concentrations in samples of natural and synthetic waters.     

Organophosphorus compounds: I. Simple,rapid, and reliable method for the simultaneous microdeterminaton of carbon,hydrogen, and phosphorus by the rapid straight empty tube method

A method for the simultaneous microdetermination of C, H, and P is presented. The organophosphorus compound is pyrolyzed in a 80-mm long silica sample capsule using the rapid straight empty tube method. Carbon and hydrogen are determined by conventional gravimetry. Oxides of phosphorus are quantitatively retained on the walls of the capsule. The P₅O₂, uptake is determined gravimetrically for the phosphorus determination.Organophosphorus compounds containing sulfur can also be analyzed following the same procedure. Electrolytic silver, heated at 550 °C, absorbs the oxides of sulfur. The results obtained fall within the acceptable limits of error.     

Beiträge zur Chemie von Phosphorverbindungen mit Adamantanstruktur. XI. Über Darstellung und Eigenschaften von Phosphoroxidsulfiden der allgemeinen Formel P4O10−nSn (n = 2−9)

Contributions to the Chemistry of Phosphorus Compounds with Adamantane-like Structure. XI. Preparation and Properties of Phosphorus Oxide Sulfides of the General Formula P₄S_10?n S_n (n = 2?9) The reaction of P₄O₁₀ with P₄S₁₀ yields a mixture of phosphorus oxide sulfides of the general formula P₄O_10?nS_n. Depending on the molar ratio P₄O₁₀: P₄S₁₀ in the starting product different amounts of the individual phosphorus oxide sulfides occuring in this reorganization product are formed. Besides the well-known P₄O₆S₄ the compounds P₄O₇S₃, P₄O₅S₅, P₄O₄S₆, P₄O₃S₇, P₄O₂S₈, and P₄OS₉ occuring for the first time were obtained by fractional distillation or crystallization. The compound P₄O₈S₂ was identified by N.M.R. spectroscopy.     

Development of porous and dispersed CRM

Porous and finely dispersed certified reference materials (CRM) were certified using the gas adsorption method. The special certification procedure for IUPAC isotherm classification types I, II, and IV is presented for meso- and macroporous materials with special emphasis on specific surface area, specific pore volume and pore width according to standards DIN 66 131, 66 134, and 66 135. Four CRMs (SiO₂, α-Al₂O₃, two transition aluminas) with a macro- and mesopore range are presented. Certification was made on the basis of BCR guidelines in connection with interlaboratory tests (altogether 38 participating laboratories, 44 various gas adsorption apparatus). Received: 25 April 1997 / Revised: 22 August 1997 / Accepted: 28 August 1997     

高频红外碳硫分析仪测定石膏矿中的三氧化硫

利用高频红外碳硫仪对石膏矿中三氧化硫含量的测定进行了研究,取得了较好的结果.方法检出限为0.003 0%.用石膏标准样品(GBW03109a,GBW03110)进行分析,测定值与认定值相符,测定值的相对标准偏差(n=9)在0.32%~0.81%之间.使用石膏标准样品(GBW03111)进行本法与国标硫酸钡重量法做比对试验,测定结果无显著性差异.加标回收率为96.4%~104.0%.     

Evaluation of high pressure oxygen microwave-assisted wet decomposition for the determination of mercury by CVAAS utilizing UV-induced reduction

The UV-induced cold vapor generation with formic acid coupled to AAS after high pressure oxygen microwave decomposition was developed for determination of total Hg in analytical samples. Certified reference materials were decomposed in 1.5 mol L^{− 1} HNO₃ and 0.6 mol L^{− 1} H₂O₂. Microwave decomposition with oxygen has allowed the use of diluted reagents. The oxygen at a pressure of ca. 15 bar was delivered during the mineralization to the closed vessel. Interference by unused residues of H₂O₂ and HNO₃ was observed. In order to overcome the negative effect of remaining oxidants pre-reduction with hydroxylammonium chloride at a concentration 0.75 mmol L^{− 1} was used. Recovery of mercury in four reference materials containing 0.20–1.99 µg g^{− 1} Hg were 99–104% of certificate values. The limits of detection and quantification in the sample solutions were determined as 0.12 and 0.38 µg L^{− 1}, which corresponds to absolute detection limits of 12 and 38 ng g^{− 1} for total mercury, respectively. The results were in good agreement with the t-test at a 95% confidence level of the certified values in the investigated reference materials. The relative standard deviation was better than 7% for most of the samples.     

Use of ion-molecule reactions and methanol addition to improve arsenic determination in high chlorine food samples by DRC-ICP-MS

Direct determination of trace arsenic in high chlorine food samples by ICP-MS is complicated by the presence of ArCl⁺ interferences, and the high first ionization energy of As (9.81 eV) also results in low analytical sensitivity in ICP-MS. In this work, two strategies based on ion-molecule reactions were successfully used to eliminate ArCl spectral interference in a dynamic reaction cell (DRC). The interference ion (⁴⁰Ar³⁵Cl⁺) was directly removed by the reaction with methane gas, and the background signal was reduced by up to 100-fold at m/z 75. Alternatively, by using molecule oxygen as the reaction gas, ⁷⁵As⁺ was effectively converted to ⁷⁵As¹⁶O⁺ that could be detected at m/z 91 where the background is low. The poor signal intensity of As or AsO was improved 3-4 times by addition of 4% methanol in the analyzed solutions. The limit of quantitation (LOQ) for ⁷⁵As (CH₄-DRC method) and ⁷⁵As¹⁶O (O₂-DRC method) was 0.8 and 0.3 ng g⁻¹ and the analytical results of seaweed and yellow croaker standard reference materials were in good agreement with the certified values. As the routine arsenic monitoring method in our laboratory, it was applied to the accuracy determination of 119 high chlorine food samples from eight different markets of Beijing.