Electrometric studies on the precipitation of thorium hydroxide

Summary On the ageing of thorium hydroxide, there is considerable change in the p_H of the system. Increase of p_H is a result of release of hydroxyl ions and decrease of p_H indicates the release of hydrogen ions from the adsorbent. Ageing before inflexion point especially with larger alkali leads to the coagulation of thorium hydroxide which eventually increases the p_H of the medium.

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Zusammenfassung Mit Alterung von Thoriumoxid treten betr?chtliche ?nderungen im p_H der Systeme auf. Der Anstieg des p_H ist ein Ergebnis des Freiwerdens von HydroxylIonen, die Abnahme zeigt das Freiwerden von Wasserstoff-Ionen vom Adsorbenten an. Alterung unterhalb des Inflexionspunktes, besonders mit gr?\erem Alkali-Gehalt, führt zur Koagulation des Thoriumhydroxids, was schlie\lich das p_H des Mediums vergr?\ert.

     

Discrimination between the permeation of H+ and OH− ions in precipitation membranes

The unique property of precipitation membranes, which allows determination of permeation rates of single ion species by measurement of current—voltage relationships, has been used to measure the transport rates of H⁺ and Oil ions. The permeation of OH^? was found to be approximately 4-5 times higher than that of H⁺ in both BaSO₄ and calcium oxalate precipitation membranes.     

Test method for the determination of hydrogen peroxide in atmospheric precipitation and water using indicator papers

A test method is proposed for the determination of hydrogen peroxide based on the oxidation of 4-chloro-1 -naphthol oro-tolidine catalyzed with horseradish peroxidase on cellulose or aldehydecellulose papers. The concentration of H₂O₂ is determined by the length of the colored zone on a test strip (3 x 80 mm) sealed into adhesive polymer film after its contact with the test solution. The analytical range of H₂O₂ is 0.1–300 mg/L. For the determination of H₂O₂ by the color intensity of indicator paper after passing 20 mL of a test solution, the analytical range is 0.005-1 mg/L. Rapid test procedures for the determination of hydrogen peroxide in atmospheric precipitation and in waste and natural waters are developed and tested (RSD ≤ 30%).     

Modification of a Dionex System 12 ion chromatograph for sequential determination of the main components in atmospheric precipitation

A modification of a Dionex System 12 ion chromatograph is described which enables organic anions (acetate and formate), inorganic cations (ammonium, sodium and potassium) and inorganic anions (chloride, nitrate and sulphate) to be determined sequentially in one measuring procedure. The modified instrument consists of a programmable controller unit, a conductimetric meter, two conductimetric detectors of the Dionex System 12 ion chromatograph, the HPIC-AS4A and HPIC-CS3 modern separation units, AMMS-1 and CMMS-1 micro-membrane suppressor columns, a unique system of valves from Dionex and two dual pumps from Biotronik. The limits of detection are between about 1 and 3 micrograms/l for chloride, nitrate and sulphate and between about 2 and 10 micrograms/l for acetate, formate, ammonium, sodium and potassium. The reliability of the method was demonstrated by analysing two NBS simulated rain water Standard Reference Materials. Some examples are given of the application of the method to the sequential determination of the main precipitation components in typical samples from urban and rural regions of the F.R.G. The ion concentrations varied between about 0.02 and 300 mg/l.     

同时测定海水中K+、Na+、Ca2+、Cl-的流动注射离子选择电极分析

建立了一种用于海水中K+、Na+、Ca2+、Cl-同时快速、自动测定的流动注射离子选择电极自动方法(FI-ISE-M),优化了方法的最佳条件:总离子强度调节液(TISAB)的组成为0.3 mmol/L K+、6.0 mmol/L Na+、1.4 mmol/L Ca2+、21.0 mmol/L Cl-及pH8.0的80 mmol/L的tris-H3BO3缓冲溶液,其流量为1.25mL/min;每次测定的样品用量仅为160μL,载流流量为1.42 mL/min,混合盘管长度为30cm(I.D.0.5 mm)。本方法的分析速度为100样/h,相对标准偏差为2.0%(n=11),标准添加回收率为94.9%～104.3%,测定范围分别为1.0～8.0 mmol/L K+、50～290 mmol/L Na+、3.2～16.0 mmol/L Ca2+、70～430 mmol/LCl-。本方法已应用于反渗透海水淡化系统的水质检测。     

Electrometric titrations with the gold electrode

Summary Massive gold because of the passivity of the oxide formed on its surface can be used as a substitute for platinum in electrometric titrations including acid-base and oxidation-reduction systems. The end points are attended with large jumps on the curves and coincide satisfactorily with those obtained using the hydrogen or platinum electrode or by other method.     

Die Reduktion von TiIV, VV CrIII, MoVI, WVI, UVI und FeIII mit Na-Pb-Legierung

Ohne Zusammenfassung     

Polarographic determination of atmospheric nitrogen oxides

A new polarographic method is described for the determination of nitrite/nitrogen oxides. The nitrite is first diazotized with p-aminobenzoic acid, followed by coupling to 8-hydroxyquinoline to produce an azo dye. This azo dye is adsorbable on a mercury drop electrode and its reduction is reversible. The linear response range is 6 x 10(-9)-3 x 10(-7) g/ml. The detection limit is 4 x 10(-9) g/ml. This method has been applied to the determination of nitrogen oxides in the air.     

Ba2+沉淀法提取生物油馏分中的酚类物质

从NaOH试剂浓度、反应温度与反应时间三个方面,对钡离子沉淀法提取不同温度段收集的生物油馏分中的酚类物质进行了实验研究,并利用气相色谱-质谱联用仪（GC-MS）对提取效果进行了分析。实验结果表明,钡离子沉淀法对愈创木酚类物质的提取效果较为突出,且NaOH浓度（1.0-6.0mol/L）、反应温度（30-50℃）与反应时间（10-40min）对愈创木酚的提取率影响较大。在NaOH浓度为5.5mol/L、反应温度为35℃、反应时间为20min时,提取率达到最大,其中,三个温度段收集的生物油即低温水相馏分、低温油相馏分与高温馏分中的愈创木酚提取率分别为34.1%、33.8%和33.5%。     

Die papier-chromatographische Trennung von CrIII, MnII, CoII, FeIII und NiII

Ohne Zusammenfassung     

Problems with the determination of heavy metals in precipitation

Summary Wet deposition is mostly determined by collecting precipitation in wet-only collectors equipped with funnels or buckets. During an intercomparison of wet-only collectors it has been found by preliminary experiments that appreciable amounts of heavy metals are adsorbed to the PE-funnel walls. Rinsing with HNO₃ and double-distilled water (equivalent height) was not sufficient to remove the material completely. From an investigation of succeeding measurements of rain water samples an increase of the metal concentration with decreasing pH-value demonstrates that a fraction of adsorbed metals appears to be removed during events with low pH. This adsorbed amount of material has to be considered as part of wet deposition and a procedure has to be developed how this amount can be determined reliably. The amounts of heavy metals analysed during our preliminary rinsing experiments was several times larger than the average concentration measured in the precipitation samples.     

UIV und GaIII

Ohne Zusammenfassung     

Problems connected with the melting of NiII, CoII and MnII cyclo-tetraphosphates

Differential thermal analysis has been used to follow the process of melting of Ni^II, Co^II and Mn^II cyclo-tetraphosphates. The melting is congruent in a dry atmosphere, being non-congruent in the presence of small amounts of water vapour: the tetraphosphate cycles are split and further condensed to chains of higher linear phosphates. Their end groups (and hence their stability) are provided by water molecules present in the atmosphere. After cooling the products have a glassy amorphous form. By repeated heating they are changed back into the cyclo-tetraphosphates with crystalline character, and the water molecules are released.     

The rate constants of the gas-phase reactions K + Cl ⇆ K+ + Cl− and KCl + M ⇆ K+ + Cl− + M from measurements in atmospheric pressure flames

Mass spectrometric studies of the ions present in H₂/O₂/N₂ flames with potassium and chlorine added have demonstrated that ionization can occur in the forward steps of K + Cl ? K⁺ + Cl^? (II), KCl + M ? K⁺ + Cl^? + M (IV), where M is any third body. Variations of [K⁺] with time in these systems have been measured and establish that the rate coefficients (in ml molecule^?1 s^?1) of the ion-producing steps are k₂ = 5 × 10^?10T^{?$\text{1}\text{2}$} exp(?10 500/T) and k₄ = 2.2 × 10⁷T^?3.5 × exp(?60 800/T). Coefficients for ion-ion recombination have been obtained from k₂ and k₄ using the equilibrium constants of (II) and (IV) and are k_?2 = 1.7 × 10^?9T^{?$\text{1}\text{2}$} and k_?4 = 1.1 × 10^?17T^?3, with each one in the ml molecule^?1 s^?1 system of units. Replacement of the N₂ in one of these flames with sufficient Ar to maintain the temperature constant leaves the measured k₂ and k_?2 unchanged, but lowers the observed k₄ and k_?4. This confirms that ion-recombination in the backward step in (II) is a two-body process, whereas in (IV) it is termolecular.     

Die papierchromatographische Trennung von AgI, PbII, HgII und TlI

Ohne Zusammenfassung     

Potentiometric Na+, K+, Ca2+, and Cl? determination of serum and whole blood in comparison to routine clinical laboratory methods

Ohne ZusammenfassungSupported by a grant of the DFG; SFB 89-Cardiology, Göttingen.