The determination of nitrate and chloride in sodium hydroxide solutions by means of cation exchangers,in the manufacturing control of alkaline batteries

The most important types of alkaline batteries are described. A method for the determination of chloride and nitrate ions in sodium hydroxide solutions has been developed The analysis is performed in the following manner: the solution is passed through a layer of a cation exchanger in the hydrogenform,wherebythe sodium hydroxide is neutralized. The liberated hydrochloric and nitric acids respectively are determined through titration. This method has been used for the manufacturing control of nickel-cadmium batteries.     

The assay of sodium citrate and sodium potassium tartrate by cation exchange and non-aqueous titrimetry

Sodium citrate and sodium potassium tartrate are assayed by passing aqueous solutions of the salts through cation exchange resin columns, concentrating the effluents from the columns, and then titrating the effluents with standard sodium hydroxide solution. Sodium citrate is assayed by titrating a solution of the salt in glacial acetic acid with standard acetous perchloric acid, the end-point being detected potentiometrically; sodium potassium tartrate is assayed by stirring the salt in excess standard acetous perchloric acid, and then backtitrating the excess acetous perchloric acid with standard acetous potassium acetate, the end-point being detected potentiometrically.     

双功能聚合物基质阳离子交换固定相的制备及其在离子色谱中的应用

离子色谱是分离分析阳离子型化合物的重要手段之一。高效阳离子交换固定相的制备研究对离子色谱技术的发展具有重要的意义。该文以丙烯酸和顺丁烯二酸酐为单体,2-巯基乙基磺酸钠为巯基改性剂,提出了聚合物基质微球巯基改性自由基聚合修饰方法,用以制备新型双功能的阳离子交换固定相。该固定相以羧基和磺酸基为功能基,仅用简单的强酸淋洗液便可以实现常规阳离子的基线分离。利用色谱学模型,对金属离子和有机胺的保留行为进行了研究。采用梯度淋洗模式,可在24 min内实现10种阳离子的分离,表明固定相具有优异的色谱性能。"巯基-烯"修饰方法简单、高效。此外,通过调节巯基改性剂的比例能够实现对固定相交换能力的调控。     

Separation of mixtures of sodium and potassium ions by charge mosaic dialysis

Charge mosaic membranes contain a mixture of anionic and cationic elements separated by thin neutral regions. In order to maintain eloctroneutrality, the overall flux of salts from electrolytic solutions through such membranes must occur with equal transport of cationic and anionic charge. The flux rate depends on the resistivities of the exchange elements and the solution composition. It is shown that Na⁺ and K⁺ can have vastly different relative transport rates depending on the selection of the membrane formulation and the receiver composition. The effect is attributed to ionic polarization of the membrane.     

Chiral lariat ethers as membrane carriers for chiral amino acids and their sodium and potassium salts

Four chiral lariat ethers 8–11 containing a (p-methoxyphenoxy) methyl side arm were used for chiral discrimination of amino acids in their zwitterionic form or as potassium and sodium salts in transport across a bulk chloroform membrane with satisfactory selectivity. The carriers that were employed exhibited different transport selectivity relative to the amino acids and their salts under study. The d/l selectivity strongly depends on the amino acids or their salts, and in some cases reverse selectivity has been obtained. The best selectivity was obtained in the case of tyrosine and its potassium salts for all carriers. The transport rates of amino acids and their salts were found to be controlled by factors such as the structure of the carriers and amino acids or their salts. Among these factors, it was also found that the side arm of the lariat ethers plays an important role in the transport process. As a consequence, the main goal of our investigation was to separate the chiral amino acids through liquid membranes.     

高亲水性强阳离子交换色谱填料的制备及其在蛋白质分析中的应用

以具有双孔结构的聚甲基丙烯酸环氧丙酯(PGMA)微球为基质,以葡萄糖进行表面亲水改性,制备了强阳离子交换色谱填料,并将其用于复杂生命体系中生物大分子的快速而高效的分离、分析与纯化。葡萄糖亲水改性增进了填料的生物相容性,提高了蛋白质样品的回收率;双孔结构及较高的比表面积赋予填料良好的柱渗透性和样品负载量。以标准蛋白质为样品,考察了该填料对生物样品的分离性能。以100 mm×4.6 mm的色谱柱分离4种蛋白质,在6 min内实现了基线分离;以溶菌酶为样品,填料的吸附容量为39.5 g/L,在蛋白质快速分离纯化分析中显示了良好的应用前景。     

消解氨溶-火焰原子发射光谱法测定丁苯橡胶中的钾、钠

和浓硝酸消解了丁苯橡胶样品，再用氨水溶解消解产物。取适量消解产物的氨溶液，加入消电离剂Li^ 配制成试液，以工作曲线法测定。对样品处理方法、消解产物的溶解性质、线性范围、干扰及检出限进行了考察。测定结果的相对标准偏差小于3．9％，加标回收率为97．3％－103．7％。建立了快速同时测定丁苯橡胶中钾、钠的火焰原子发射光谱法。     

Enantioselective transport of amino acids as their potassium and sodium salts by optically active diaza-18-crown-6 ethers having arene sidearms

The enantioselective transport of amino acids as their sodium and potassium salts has been investigated by optically active diaza crown ethers. The reversed enantioselectivity of chiral crown ether 1 was observed.     

Succinates and maleates of some cardenolides,and their potassium salts

The succinates of corotoxigenin, digitoxigenin, and oleandrigenin, and the maleate of strophanthidin, and their potassium salts, have been synthesized. In contrast to the initial cardenolides (1, 4, 7, and 10), the succinates (2, S, and 8) and the maleate (11) and their potassium salts (3, 6, 9, and 12) possess no cardiotonic activity.Ukrainian Pharmaceutical Academy, Kharkov-2, ul. Pushkinskaya, 53. State Scientific Center for Drugs, Kharkov-85 ul. Astronomicheskaya 33. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 568–571, July–August, 1996 Original article submitted February 7, 1996     

Determination of the atomic charge on sodium in sodium salts by numerical integration — a theoretical investigation

The electron density difference in a NaSCN crystal is set up from the ab initio densities of Na⁺ and SCN^? ions and compared to the experimental counterpart based on X-ray diffraction measurements. Numerical integration over the electron density difference is executed around the Na⁺ ion. The atomic charge (+0.20e) derived in this way is in good agreement with the analogous experimental charge (+0.27e) The low experimental value cannot therefore be taken as an indication for a predominantly non-ionic structure of NaSCN and similar sodium salts     

Transport properties of a cation exchange membrane with sodium and potassium as counterions

The measured transport properties for the cation exchange membrane Ionics 61AZL389 in the Na+ + K+ mixed counterion states are presented. The transport numbers of counterions and of water as well as the specific conductivity of the membrane showed approximately linear behaviour as a function of ionic fraction in the membrane. It is therefore concluded that it is possible to estimate the transport numbers of counterions from known selectivity coefficients and concentrations in the external solution. The transport number of water and the specific conductivity of the membrane can also be evaluated reasonably accurately using data for membranes in pure homoionic states. The separation ratio was found to be constant over a wide range of concentration ratios under the hydrodynamic conditions used experimentally.     

Experimental validation of theoretical potassium and sodium cation affinities of amides by mass spectrometric kinetic method measurements

In this study the theoretical Gaussian-2 K(+)/Na(+) binding affinities (enthalpies) at 0 K (in kJ mol(-1)) for six amides in the order: formamide (109.2/138.5) < N-methylformamide (117.7/148.6) < acetamide (118.7/149.5) < N,N-dimethylformamide (123.9/156.4) < N-methylacetamide (125.6/157.7) < N,N-dimethylacetamide (129.2/162.6), reported previously (Siu et al., J. Chem. Phys. 2001; 114: 7045-7051), were validated experimentally by mass spectrometric kinetic method measurements. By monitoring the collision-induced dissociation (CID) of K(+)/Na(+)-bound heterodimers of the amides, the relative affinities were shown to be accurate to within +/-2 kJ mol(-1). With these six theoretical K(+)/Na(+) binding affinities as reference values, the absolute K(+)/Na(+) affinities of imidazole, 1-methylimidazole, pyridazine and 1,2-dimethoxyethane were determined by the extended kinetic method, and found to be consistent (to within +/-9 kJ mol(-1)) with literature experimental values obtained by threshold-CID, equilibrium high-pressure mass spectrometry, and Fourier transform ion cyclotron resonance/ligand-exchange equilibrium methods. A self-consistent resolution is proposed for the inconsistencies in the relative order of K(+)/Na(+) affinities of amides reported in the literature. These two sets of validated K(+) and Na(+) affinity values are useful as reference values in kinetic method measurements of K(+)/Na(+) affinity of model biological ligands, such as the K(+) affinities of aliphatic amino acids.     

Radiation stability of macro-porous and gel-type cation exchangers

Macro-porous cation exchange resin Diaion CPK-08 and gel type cation exchange resin Dowex 50WX8 were irradiated with γ-rays from⁶⁰Co, while soaked in distilled water, 0.5M HNO₃ or 4M HNO₃, and the ion-exchange properties, such as strong- and weak-acid capacities, moisture content and wet resin volume, were examined in relation to absorbed dose. There was no appreciable difference between the radiation stabilities of the two cation exchangers. Increase of HNO₃ concentration reduced the loss of strong-acid capacity and increased the decross-linkage and the weak-acid capacity. Elution characteristics of¹³⁷Cs and⁹⁰Sr from columns packed with γ-irradiated resin were examined and the column distribution ratio of these radionuclides and the theoretical plate number were calculated. These values decreased with the increase of absorbed dose. Diaion CPK-08 was packed into a pressurized column and irradiated with γ-rays at a dose rate of 2·10⁶ R/hr, while water was passed through the column at a constant flow rate. The greatest change of the resin properties was observed at an upper stream position from the position of the highest radiation dose of 2·10⁶ R/hr.     

Thermodynamics of aqueous mixtures of sodium chloride,potassium chloride,sodium sulfate,and potassium sulfate at 25°C

Aqueous solutions of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate can be mixed in six ways to give ternary mixtures. Two of these have already been studied and results are now presented for the remaining four systems: H₂O–NaCl–K₂SO₄, H₂O–Na₂SO₄–K₂SO₄, H₂O–KCl–Na₂SO₄, and H₂O–KCl–K₂SO₄.     

Solubilization and precipitation of cholesterol in aqueous solution of bile salts and their mixtures

Solubilization of cholesterol by mixed micelles of sodium chenodeoxycholate with sodium ursodeoxycholate was investigated in carbonate-tetraborate buffer (Kolthoff) solution at pH 10 and 37°C. It was found that the mixing of the two bile salts gives a negatively synergetic effect on solubilization of cholesterol. The solubilizing power of bile salts for cholesterol was remarkably influenced with the change in mole fraction of sodium ursodeoxycholate (X _UDC).The behavior of bile salt solutions saturated with cholesterol was examined by measuring the surface tension. Two break points were observed in the curves of surface tension vs. concentration. The break points seem to correspond to a CMC in the absence of solubilized cholesterol and another CMC in the presence of solubilized cholesterol inside bile salt micelle.     

Halide affinity for the water-air interface in aqueous solutions of mixtures of sodium salts

The water-air interface plays a critical role in many physical and chemical processes of the Earth's atmosphere. In particular, heavy halide ions are strongly involved in processes of fundamental importance in determining the prevalence of many atmospheric components through heterogeneous reactions at the water-air interface. In this work, molecular dynamics simulations are used to study the halide enhancements at the water-air interface in the case of mixtures of Cl(-), Br(-), and I(-) ions. The results show a pattern of enhancement directly correlated to the anion polarizability. This effect is explained in terms of the charge distribution across the slab resembling an electrical double layer. As a result, the anions with higher polarizability lower the system's potential energy by enhancing their presence at the interface.