锌粉-硼砂-硼酸熔融-碘酸钾滴定法测定高硅锡精矿中的锡

针对高硅锡精矿中锡的测定时通常用锌粉-氢氧化钠熔融,精密度差,不能满足分析要求的问题,建立了锌粉-硼砂-硼酸熔融,盐酸浸取,铝粒将锡还原,碘酸钾滴定法测定高硅锡精矿中锡的分析方法。方法结果稳定,精密度好,相对标准偏差在0.19%~0.55%,加标回收率在96.9%~105%。分析结果能够满足高硅锡精矿中锡的测定要求。     

碘酸钾滴定法测定分银渣中的锡含量

采用碘酸钾滴定法测定分银渣中的锡含量。试样用过氧化钠熔融,水浸酸化,加铁粉过滤除杂质;加铝片还原,待反应平静后加热煮沸至冒大泡,冷却至室温;以淀粉为指示剂,碘酸钾滴定至淡蓝色为终点。对试样进行11次平行测定,相对标准偏差(RSD)小于1.2%,加标回收率在99%~101%。方法流程短,除杂质效果好,结果准确。     

The Structures of Nitrosyl Fluoride and Nitrosyl Chloride in the Solid State

Nitrosyl fluoride and nitrosyl chloride are crystallized from the melt. The crystal structures are made up by ON–F and ON–Cl molecules with only weak intermolecular interactions. ON–F: a = 411.0(2), b = 439.1(2), c = 1020.2(4) pm, space group P2₁2₁2₁. ON–Cl: a = 1084.0(2), b = 543.5(1), c = 409.3(1) pm, space group Pnma. Both molecules have considerable longer nitrogen‐halogen bonds and shorter nitrogen‐oxygen bonds in the solid than in the gaseous state. These differences between gas and solid state structure are expressed much stronger in ON–Cl than in ON–F. ON–F functions as a solvate molecule in the cation of NO⁺(NOF)₂IF₈^–. Here the ON–F molecule has a drastically shortened NO and lengthened NF bond. NO⁺(NOF)₂IF₈^–: a = 618.9(1), b = 1039.4(1), c = 2842.1(1) pm, space group P2₁2₁2₁.     

Nature of hydration shells of a polyoxy‐anion with a large cationic centre: The case of iodate ion in water

The structural nature of the solvation shells of an iodate ion, which is known to be a polyoxy‐anion with a large cationic centre, is investigated by means of Born–Oppenheimer molecular dynamics (BOMD) simulations using BLYP and the dispersion corrected BLYP‐D3 functionals. The iodate ion is found to have two distinct solvation regions around the positively charged iodine (iodine solvation shell or ISS) and the negatively charged oxygens (oxygen solvation shell or OSS). We have looked at the spatial, orientational, and hydrogen bond distributions of water in the two solvation regions. It is found that the water orientational profile in the ISS is typical of a cation hydration shell. The hydrogen bonded structure of water in the OSS is found to be very similar to that of the bulk water structure. Thus, the iodate ion essentially behaves like a positively charged iodine ion in water as if there is no anionic part. This explains why the cationic character of the iodate ion was prominently seen in earlier studies. The arrangement of water molecules in the two solvation shells and in the intervening regions around the iodate ion is further resolved by looking at structural cross‐correlations. The electronic properties of the solvation shells are also looked at by calculating the solute–solvent orbital overlap and dipole moments of the solute and solvation shell water. We have also performed BOMD simulations of iodate ion‐water clusters at experimentally relevant conditions. The simulation results are found to be in agreement with experimental results. © 2018 Wiley Periodicals, Inc.     

Sol—Gel Derived Carbon Ceramic Electrode Bulk—Modified with Tris（1,10—phenanthroline—5,6—dione） iron （Ⅱ）Hexafluorophosphate and Its Use as an Amperometric Iodate Sensor

A surface‐renewable tris(1, 10‐phenanthroline‐5, 6‐dione) iron (D) hexafluorophosphate (FePD) modified carbon ceramic electrode was constructed by dispersing FePD and graphite powder in methyltrimethoxysilane (MTMOS) based gels. The FePD‐modified electrode presented pH‐dependent voltammetric behavior, and its peak currents were diffusion‐controlled in 0.1 mol/L Na₂SO₄ + H₂SO₄ solution (pH = 0.4). In the presence of iodate, dear electrocatalytic reduction waves were observed and thus the chemically modified electrode was used as an amperometric sensor for iodate in common salt. The linear range, sensitivity, detection limit and response time of the iodate sensor were 5 × 10^?6–1 × 10^?2 mol/L, 7.448 μA·L/ mmol, 1.2 × 10^?6 mol/L and 5 s, respectively. A distinct advantage of this sensor is its good reproducibility of surface‐renewal by simple mechanical polishing.     

柯衣定褪色光度法测定食盐中碘

建立了加碘盐中碘含量测定新的光度分析法, 借助于在H2SO4介质中碘酸根氧化柯衣定使其褪色, 褪色前后的吸光度之差ΔA与碘含量成正比进行测量的. 柯衣定在波长455 nm处有强吸收, 碘含量在0～50 μg/mL范围内呈线性关系, 方法的相对标准偏差小于0.84%, 回收率为101.7%～105.7%.     

异硫氰酸荧光素荧光猝灭法测定痕量碘酸根

碘酸根与碘离子反应生成游离碘使异硫氰酸荧光素的荧光猝灭,λｅｘ为４８７ｎｍ,λｅｍ为５１７ｎｍ,碘酸根含量在２－８μｇ／Ｌ范围内与荧光猝灭程度有良好线性关系,检测限为０．７４μｇ／Ｌ,该法灵敏度高,操作简便,用于含碘含盐中微量碘酸根的测定,结果满意。     

Book review

NEUTRON RADIOGRAPHY HANDBOOK. Compiled by the Neutron Radiography Working Group under the auspices of the Commission of the European Communities, Joint Research Centre. Edited by P. Van der Hardt and H. Roltger. Price DFL 60.00 (D. Reidel Publishing Co., Dordrecht, Boston, London 1981).     

Investigation of iodine liberation process in redox titration of potassium iodate with sodium thiosulfate

Potassium iodate is often used as a reference material to standardize a sodium thiosulfate solution which is a familiar titrant for redox titrations. In the standardization, iodine (triiodide) liberated by potassium iodate in an acidic potassium iodide solution is titrated with a sodium thiosulfate solution. The iodine liberation process is significantly affected by the amount of acid, that of potassium iodide added, the waiting time for the liberation, and light; therefore, the process plays a key role for the accuracy of the titration results. Constant-voltage biamperometry with a modified dual platinum-chip electrode was utilized to monitor the amount of liberated iodine under several liberation conditions. Coulometric titration was utilized to determine the concentration of a sodium thiosulfate solution on an absolute basis. Potassium iodate was assayed by gravimetric titration with the sodium thiosulfate solution under several iodine liberation conditions. The liberation process was discussed from the changes in the apparent assay of potassium iodate. The information of the appropriate titration procedure obtained in the present study is useful for any analysts utilizing potassium iodate to standardize a thiosulfate solution.     

Sol-Gel Derived Carbon Ceramic Electrode Bulk-Modified with Tris(1,10-phenanthroline-5,6-dione)iron(II) Hexafluorophos-phate and Its Use as an Amperometric Iodate Sensor

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