Determination of the stability constants of uranyl complex with 8-hydroxyquinolinium sulfate

8-Hydroxyquinoline (8-HOQ) is known as an important chelating agent for several metal ions. This compound is practically insoluble in water. For this reason, in this study its water soluble sulfate salt has been used for complexing uranyl ions and the stability constants of the complex have been determined. The Irving-Rosotti method computing the Calvin-Bjerrum pH-titration data, was applied. Finally, the stability constants of the complex formed between (8-HOQN-H)₂SO₄ and uranyl ions were found to be lgK₁=8.25 and lgK₂=4.15, the overall stability constant being {ie55-1}.     

99mTc-labelled human serum albumin: Chemical and electrochemical labelling methods

The labelling of human serum albumin /HSA/ with^99mTc has been investigated using a chemical method /stannous citrate/ and electrolytically generated tin/II/ ions. A comparative study of various chemical parameters and current intensities has been carried out in order to find the optimal conditions for labelling. The labelling yield was over 95%, for the chemical and electrolytical methods.     

Determination of bismuth, indium and lead in geological samples by electrothermal AAS Part 2. Comparative study of palladium and molybdenum containing chemical modifiers*

A comparative and systematic study has been carried out of the effects of palladium and molybdenum containing chemical modifiers, such as Pd + Rh, Pd + Pt, Pd + Ru, Pd + Rh + Pt, Pd + Rh + Ru, Mo + Pd, Mo + Rh, Mo + Ru and Mo + Pt and additionally tartaric acid (TA) as a reducing agent together with mixed modifiers for the thermal stabilization of Bi, In and Pb in a Zeeman electrothermal atomic absorption spectrometer (ETAAS). The effect of the mass ratios of the mixed modifier components on the maximum pretreatment temperature for the analytes has been determined. The modifier mixtures of Pd + Rh + Pt, Mo + Pd + TA and Mo + Pt + TA were found to be especially powerful for the determination of Bi, In and Pb. These mixed modifiers could increase the ashing temperatures of the analytes up to 1250–1400° C. They were applied to the determination of Bi and Pb in dissolved geological reference samples and accuracy and precision of the method were thereby enhanced. The percent relative error was decreased from 20.0 to 0.4 for Bi and from 10.5 to 0.3 for Pb, depending on the sample type. Received: 9 May 1997 / Revised: 19 August 1997 / Accepted: 20 August 1997     

Evard Immanuel Hjelt (1855–1921): Finnish Chemist and Historian of Chemistry

Although today unjustly neglected abroad and often even in his native land, Edvard Immanuel Hjelt (1855–1921), was an exceptionally gifted, dedicated, and multifaceted individual who made important contributions to chemistry, the history of chemistry, politics, and the management of national and international affairs. Little information about him is available in English. The present article supplements the only two English sources available [1, pp 66–83; 2] and makes this chemist-statesman better known to those chemists and historians who do not read Swedish or Finnish.In this section we present articles by leading scientific historians that chronicle the important events, persons, and publications that make up the rich history of chemical science. The history, and the articles in this ection often make that very clear. Chemists and their research are always influenced by current events. These articles are intended to describe the setting in which important discoveries occurred and to humazine their discoveres.     

Elimination of bremsstrahlung in activation analysis by the deflection of β-particles in a magnetic field

The structureless background at X-ray and low energy -ray region, resulting from bremsstrahlung due to the stopping of -radiations, causes serious problems in nuclear spectroscopy. In this study, in order to reduce the background and therefore to increase the sensitivity of the nuclear analytical technique and the number of elements observable, a methodology is developed to deflect the -particles by a magnetic field. The experimental setup consists of a permanent magnet /1 kG/, Ge/Li/ solid-state detector, and multichannel analyzer.     

Cyclodextrin Solubilization of the Antibacterial Agents Triclosan and Triclocarban: Effect of Ionization and Polymers

The natural β-cyclodextrin (βCD) and its complexes have limited solubility in aqueous solutions. This low aqueous solubility, as well as low aqueous solubility of the guest molecule (i.e. triclosan or triclocarban (TCC)), can result in low complexation efficiency (CE). The purpose of this study was to enhance the apparent intrinsic solubility (S ₀) of the guest molecule and its βCD complexes through ionization and addition of auxiliary compounds such as polymers, amino acids and metal ions. Both triclosan (pK _a 7.9) and TCC (pK _a 12.7) are weak acids. Addition of ethanol to the complexation medium enhanced S ₀ of both triclosan and TCC but at the same time ethanol lowered the stability constant (K _c ) of their βCD complexes resulting in overall lowering of CE. Addition of small amount of water-soluble polymers enhanced the βCD solubilization of both guests, and addition lysine enhanced the solubilization of TCC. Ionization of triclosan resulted in significant enhancement of CE and enhanced triclosan release from tablets containing triclosan/βCD complex. The effect of ionization was not as pronounced in the case of TCC.This revised version was published online in July 2005 with a corrected issue number.     

Removal of strontium ions by a crosslinked copolymer containing methacrylic acid functional groups</p> </p>

Summary A tail-made polymer matrix is proposed to remove strontium ions from aqueous solutions. The removal behavior of strontium ions on a crosslinked copolymer containing methacrylic acid as functional groups was investigated as a function of sorptive concentration, time, temperature and pH. It was observed that an increase of these parameters enhanced the removal of Sr(II) ions from aqueous solution. It is found that a maximum adsorption of Sr(II) ions can be obtained on the crosslinked copolymer after 30 minutes and at pH 8. The increase of Sr(II) ion concentration in the solution resulted in an increase in the amount of Sr(II) ions adsorbed on the crosslinked copolymer containing methacrylic acid as functional groups. However, after a maximum of Sr(II) concentration in the solution, the percentage of adsorbed Sr(II) ions decreased. The adsorption data are well represented by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. The adsorption capacity of the copolymer and the free energy change were calculated by using the D-R isotherm. For the adsorption of Sr(II) ions on the crosslinked copolymer the thermodynamic parameters (DH°,DS° andDG°) were calculated.</p> </p>     

Determination of trace elements in Na-bentonitic clay by INAA in Turkey

Instrumental neutron activation analysis was applied to the determination of trace elements in a Na-bentonitic clay. The irradiation was done in the Triga Mark II type reactor of ITU Nuclear Energy Institute. The sample was irradiated in two steps for short- and long- lived isotopes. After irradiation, spectra were taken using a germanium detector, multichannel analyzer Canberra System 100 and a fitting program called Sampo 90. The spectra of short-lived isotopes were analyzed to determine Al, Mg, Na, K, Ca, Ti elements and Mn, V trace elements. The spectra of long-lived isotopes were analyzed to determine Sc, Br, Sb, Cs, La, Ce, Sm, Yb, Hf, Pa, Np trace elements.     

Natural radioactivity in soil samples of Kocaeli basin, Turkey

The city of Kocaeli is in the western part of Anatolia in Turkey and has a population of approximately 1.000.000. There is no information about radioactivity in the Kocaeli soils samples so far. For this reason, the concentrations of the natural radionuclides in soil samples from 27 different sampling stations in Kocaeli Basin and its surroundings have been determined. The results have been compared with other radioactivity measurements in different country"s soils. The typical concentrations of ¹³⁷Cs, ²³⁸U, ⁴⁰K, ²²⁶Ra, ²³²Th found in surface soil samples ranged from 2±0.6 to 25±6 Bq/kg, from 11±4 to 49±10 Bq/kg, from 161±30 to 964±127 Bq/kg, from 10±4 to 58±11 Bq/kg, and from 11±3 to 65±13 Bq/kg, respectively.