Electrical conductivities of potassium ferrites doped with divalent metal oxide

The electronic and ionic conduction in three kinds of potassium ferrites with β-alumina structure was studied. Undoped ferrite, K₂O·6Fe₂O₃, prepared by sintering at 1400°C after prefiring a mixture of potassium carbonate and ferric oxide, was a mixed conductor with about 1% ionic conduction and predominantly electronic conduction. The nickel- or zinc-doped potassium ferrite showed decreasing conductivity in the range of a single phase as the content of dopant increased. Variations of the electronic conduction in the doped potassium ferrites were assigned to changes of ferrous ion concentration accompanied by structural changes in the spinel-like blocks. Potassium ion conductivities of the three sorts of samples were estimated from the total conductivities and the transport numbers obtained by dc-polarization technique and electrolysis method. The decreases of the ionic conductivities were explained by narrowing of the alkali-oxygen slot caused by doping.     

Determination of potassium by titrimetry

Epp's method is modified by the addition of solid calcium hydroxide to the sample solution. This simplified the procedure, increased the rapidity and lessened the sources of error. With samples containing various ions except ammonium ion, potassium (conc. of KCl 0.25 to 1.8 x 10(-2)M) was determined within 0.4% of error, by means of corrections for the existence of a large quantity of sodium chloride and for the solubility of potassium tetraphenylborate.     

Determination of cadmium in mixtures with metal ions

A method for the determination of cadmium microamounts in mixtures with metallic ions withE _1/2 near toE _1/2 of cadmium is discussed. For higher selectivity cadmium was extracted in the form of the pyridin-thiocyanate complexes prior to polarography.

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Bestimmung von Cadmium(II) neben anderen Metallionen

Zusammenfassung Es wird eine polarographische Methode zur Bestimmung von Cd(II) neben anderen Metallionen mitE _1/2 naheE _1/2(Cd) diskutiert. Zur Erhöhung der Selektivität und Genauigkeit wird eine Pyridin-Thiocyanat-Extraktion vorgeschalten.

     

重量法测定偏钒酸钾中钾的含量

对钾离子的测定方法有原子吸收分光光度法、电位滴定法,ICP AES法,X射线荧光光谱法等。但这些方法对测定高含量的钾,不是误差较大,就是手续较繁琐。可重量法测定钾还是较为少见。本文参考GB15063 94复混肥料中钾含量测定方法[1]及比较生产单位所用的高氯酸钾重量法测定偏钒酸钾中钾,经过试验,发现重量法测定高含量钾较有潜力;但高氯酸钾重量法大量的偏钒酸易形成钒酸盐同时部分析出,夹杂在高氯酸钾中,而使结果偏高,而用四苯基合硼酸钠溶液沉淀偏钒酸钾中钾离子,大量的钒离子对测定也有干扰,通过试验,本文用EDTA络合钒及其它微量阳…     

Effect of metal ions on the determination of semicarbazide hydrochloride with potassium bromate

Semicarbazide can be titrated quantitatively with potassium bromate in the presence of nickel(II), cobalt(III) and manganese(II) but copper(II) causes serious interference. The effects of copper ions on the reaction between potassium bromate and semicarbazide are investigated and the optimum conditions under which the reaction is quantitative are indicated.     

Determination of thiocyanate by potassium bromate

Summary Estimation of thiocyanate, based on its titration with standard KBrO₃ solution in presence of 1.5–3.0 N hydrochloric acid, is described. The end point is determined either potentiometrically or with methyl orange as indicator.Sincere thanks of the author are due to Professor S. S. Joshi for research facilities.     

KMnO_4-甲醛流动注射化学发光法测定木犀草素

在酸性介质中,木犀草素在KMnO4-HCHO体系中产生化学发光,据此建立了一种简便、快速测定木犀草素的化学发光新方法。化学发光强度与木犀草素的浓度在5.0×10-8~1.5×10-5g/mL范围内呈现出良好的线性关系。其检测限(3σ)为3.0×10-8g/mL,对8.0×10-7g/mL的木犀草素溶液进行11次平行测定,相对标准偏差为2.8%。方法可应用于实际样品和合成样品中木犀草素的测定。并探讨了反应的机理。     

Determination of ascorbic acid by potassium iodate

Summary Results are given for a two stage oxidation in the ascorbic acid-KIO₃ reaction under controlled conditions of acidity. The first step corresponds to the Landolt reaction and the second end point is obtained by the classical Andrews method. The reproducibility and accuracy of the results calculated on the basis of the two successive end points constitute an interesting new feature of this redox reaction involving the use of KIO₃ as a primary standard for the determination of ascorbic acid.Our sincere thanks are due to Professor S. S. Joshi for kind interest in the work and to the National Institute of Sciences of India for award of a Research Fellowship to one of us (G. S. D.).     

Determination of nitrogen by the decomposition of organic compounds with metallic potassium

Summary A micromethod was proposed for the determination of nitrogen in organic compounds, based on the fusion of organic substances with metallic potassium and subsequent complexonometric determination of the cyanide ions in the alkaline melt. The error of the method is +0.3%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimisheskaya, No. 7, pp. 1262–1264, July, 1965     

Dissolving metal reductions with sodium potassium alloy in the presence of 18-crown-6

The dissolving metal reduction of organic compounds can be performed in THF utilizing sodium potassium alloy in the presence of a catalytic amount of 18-crown-6.     

Determination of heavy metal traces in metallic materials with IDMS

Summary Two pure copper samples were analysed for Cr, Ni, Zn, Cd, and Pb with isotope dilution mass spectrometry (IDMS) as a part of a certification campaign of the European Community Bureau of Reference in Brussels. Additionally, one commercially available copper powder was determined for Zn, Cd, and Pb. After dissolution of the sample in aqua regia Pb was separated from the matrix by anodic electrodeposition, the other elements by anion-exchange chromatography. Positive thermal ions were produced in a single-filament ion source using the silica gel technique with phosphoric acid for Zn, Cd, and Pb and with boric acid for Cr and Ni. Most of the heavy metals could be determined with relative standard deviations of about 1% down to the ng/g level. The detection limits were 13 ng/g for Zn, 4 ng/g for Ni, 2 ng/g for Cr, 1 ng/g for Pb, and 0.03 ng/g for Cd. The results were compared with those obtained by another IDMS laboratory and by other methods applied during the certification campaign.

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Bestimmung von Schwermetallspuren in metallischen Werkstoffen mit der massenspektrometrischen IsotopenverdünnungsanalyseTeil 1. Bestimmung von Cr, Ni, Zn, Cd und Pb in reinem Kupfer

     

Determination of antimony(III) with potassium hexacyanoferrate(III)

The determination of antimony(III) with potassium hexacyanoferrate(III) in 5M hydrochloric acid medium and in the presence of 40% v/v acetic acid is described. Ferroin is used as the indicator. Antimony has been determined in tartar emetic, solder and pig lead. Arsenic(III) does not interfere.     

流动注射化学发光法测定青霉素G钾

在甲醛的存在下,酸性KMnO4与青霉素G钾能够产生很强的化学发光,从而建立了KMnO4-甲醛-青霉素G钾化学发光体系来测定青霉素G钾.青霉素G钾的测定线性范围为2.0×10-7～1.0×10-5 g/mL,方法的检出限为1.4×10-7 g/mL,对4.0×10-7 g/mL的青霉素G钾进行11次平行测定,相对标准偏差为1.0%,用此法测定青霉素G钾取得了较好的结果.     

Dehydrocondensation of triorganosilanes with piperazine and some aliphatic amines in the presence of potassium metal

Reaction of CH₃(C₆H₅)₂SiH with C₄H₉NH₂ in the presence of potassium metal gives, instead of the expected CH₃(C₆H₅)₂SiNHC₄H₉, benzene, diphenyl, and what is apparently a hitherto unknown substituted cyclodisolazane. The Si-C₆H₅ bond is broken not only by alkali metals, but also by their amides. For the case of piperazine it is shown that heterocyclic diamines react considerably more readily with trialkylsilanes than do aliphatic secondary amines.     

Determination of potassium in fatty acid methyl esters applying an ion-selective potassium electrode

An easy and inexpensive method of potassium determination in fatty acid methyl esters (FAME) applying an ion-selective potassium electrode (ISE-K) is presented. FAME are considered alternative fuel for diesel engines. Simple apparatus and procedure were developed to avoid contact of ester samples with the sensitive ISE-K membrane, which can damage the ISE membrane surface in long time operation. Using different FAME samples with a wide range of known potassium content a calibration curve was constructed. Among all samples, ISE-K satisfactory predicted potassium content in FAME as identified by the AAS reference method.     

Molten potassium pyrosulfate: The reactions of seven metal oxalates

The reactions of Li₂C₂O₄, Na₂C₂O₄, K₂C₂·H₂O, CaC₂·H₂O, ZnC₂O₄, La₂(C₂O₄)₃ and K₂TiO(C₂O₄)₂· 2H₂O with K₂S₂O₇ were investigated using thermal methods of analysis. Reaction products were analysed by various techniques. It was found that anhydrous oxalates reacted with K₂S₂O₇, evolving a mixture of CO₂ and CO with the formation of K₂SO₄ and the corresponding metal sulfates, which, in the reactions of ZnC₂O₄ and K₂TiO(C₂O₄)₂ 2H₂O, probably existed as K₂[Zn(SO₄)₂] and K₄[Ti(SO₄)₄], respectively. Water was found to be an additional product in the hydrated metal oxalate reactions. The stoichiometries of these reactions have been established from the thermogravimetric and acidimetric results.     

Determination of potassium in sea-water by capillary isotachophoresis

Summary A new analytical procedure for the determination of potassium in sea-water was developed using capillary isotachophoresis and ion-exchange. After the sea-water sample was passed through the column packed with an ammonium form cation-exchange resin, sodium ion was removed with 2×10^–2 mol/l ammonium chloride solution and then potassium ion was eluted with 3×10^–1 mol/l ammonium chloride solution. Simultaneous determination of potassium and sodium ions was performed with a newly developed electrolyte system; the leading electrolyte was 5 mmol/l cesium hydroxide containing 2 mmol/l 18-crown-6, 0.01% hydroxypropyl methylcellulose (HPMC) and 70% methanol; the terminating electrolyte was 5 mmol/l tetrabutylammonium bromide containing 0.01% HPMC and 70% methanol. A large amount of ammonium in the eluate did not interfere with the isotachophoretic measurement of potassium and sodium ions. A linear working curve was obtained for artificial sea-water samples containing up to 700 mg/l potassium ion. The proposed method was applied to the determination of potassium in surface and bottom sea-water samples.

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Kaliumbestimmung in Meereswasser durch Capillar-Isotachophorese

     

镧对心肌细胞钾通道的作用研究

用全细胞膜片钳记录方式研究了La^3^+对大鼠心室肌细胞钾通道的作用机理。对酶解分离的大鼠心室肌细胞施一跃迁电压可引出一非钙依赖性电压去激活的外向钾电流。将10μmol/LLa^3^+加入细胞外液后，非钙依赖性电压去激活的外向钾电流明显减小，这提示在大鼠心室肌细胞钾通道上存在La^3^+结合位点。