THE INTERACTION OF BIS[2-MERCAPTOETHANESULFONATO (2−)-Sl,BIS[L-CYSTEINATO(1−)-S], AND BIS[L-PENICILLAMINATO(1−)-Sl- DIMETHYLTIN (IV), WITH RAT HEMOGLOBIN: A119Sn MöSSBAUER SPECTROSCOPIC STUDY

Abstract

The title compounds, representative of classes of diorganotin (IV) derivatives active against murine leukemia P-388. interact with rat hemoglobin (selected as a model protein) by: i) co-crystallization. with formation of microcrystalline pellets, and: ii) diffusion into hemoglobin crystals from the supernatant solution (as determined for the 2-mercaptoethanesulfonato derivative). The nature of the Me₂Sn^IV species in hemoglobin has been investigated by ¹¹⁹Sn Mössbauer spectroscopy, and a C₂SnS₂ tetrahedral geometry has been assigned by the point-charge model rationalization of the nuclear quadrupole splitting parameter.

Binding into crystalline hemoglobin has been ascribed to Coulomb interactions and to hydrogen bonding between the sulfonate and the aminoacid tails of the organotin (IV) derivatives and functional groups of the globin.     

High precision instrumental neutron activation analysis of Sn in cassiterite with the aid of an227Ac−Be isotopic neutron source

A non-destructive method has been developed for the precise and accurate determination of Sn in cassiterite ores. Irradiation is performed by means of a 6.6 Ci²²⁷Ac−BE isotopic neutron source with a total neutron output of 10⁸ n·sec⁻¹. Samples are pellets pressed from a mixture of cassiterite powder and wax as a binding material. With a 4 hrs analysis time and a relative precision of 0.45%, the new method is faster and at least as precise as any existing destructive chemical method. The accuracy is proved to be better than that of the commonly used iodimetric titration method.     

Preliminary study on analysis and removal of wax from a Carrara marble statue

Abstract

This preliminary study has mainly focused on the wax identification by nuclear magnetic resonance (NMR) and removal. Wax is used for many purposes in the field of art as protective coatings on wooden, stone or metal objects. From the comparison of the spectra H NMR and in particular with the correspondence of the resonance peaks of the samples taken from the statue and beeswax and paraffin, we can conclude that the wax applied on the statue surface is beeswax. From our data, it can be concluded that, to remove the beeswax, from any stone support, the more effective solvent is the mixture of cyclohexane/ethyl acetate. The removal percentages ranged from 19 to 99%. Lower percentages of removal have been observed in the case of yellow marble, probably because of its high porosity. We can affirm that, this solvent mixture can be employed in real art objects using cotton swabs to remove protective wax.     

Determination of fluorine in zinc ores using an isotope neutron source based automated neutron activation analysis system

A method has been developed for routine determination of fluorine in zinc sulfide ores by activation with fast neutrons from a 6.6 Ci²²⁷Ac−Be isotope source and counting of the 4.5 to 7 MeV gamma-rays of the product nuclide¹⁶N. Samples and standards consist of pellets pressed from a mixture of powdered material with wax or graphite. Samples and standards alternate in a sequence of 20 seconds irradiation, 4 seconds decay and 20 seconds counting. This analysis sequence, including the computation of the analysis results from the counting data automated by means of a LSI-11 Microprocessor with 12K×16 bit memory. The zinc ores, containing 0.3 to 0.7% fluorine have been analysed with a precision ranging from 1.56 to 1.33% relative. As a test for the reliability of the method, three standard reference materials were analysed in the same way as the zinc ore samples.     

The Thin-Layer Chromatographic Separation of Halogenated Fumigants as Ammonium Halides and Their Subsequent Determination by Meca

Abstract

A method is described for the determination of several pesticides containing bromine and chlorine by molecular emission cavity analysis (MECA). The pesticides were decomposed in an oxygen flask and the combustion products dissolved in aqueous ammonia. The ammonium halides were separated by TLC using microcrystalline cellulose adsorbent. After scraping from the TLC plates and dissolving in water the separated components were quantitated by MECA using either the InBr (Λ_max = 376 nm) or the InCl (Λ_max = 360 nm) emission bands. Recoveries of over 96% were obtained. Soils fortified with l, 2-dibromo-3-chloropropane at levels of 5–25 ppm were extracted using shaking and distillation procedures. Subsequent analysis showed that the shaking extraction gave a recovery of 92% compared to 85% from acid refluxing.     

Glass transition temperature and thermal decomposition of cellulose powder

Cellulose powder and cellulose pellets obtained by pressing the microcrystalline powder were studied using differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermal gravimetry (TG). The TG method enabled the assessment of water content in the investigated samples. The glass phase transition in cellulose was studied using the DSC method, both in heating and cooling runs, in a wide temperature range from −100 to 180 °C. It is shown that the DSC cooling runs are more suitable for the glass phase transition visualisation than the heating runs. The discrepancy between glass phase transition temperature T _g found using DSC and predictions by Kaelbe’s approach are observed for “dry” (7 and 5.3% water content) cellulose. This could be explained by strong interactions between cellulose chains appearing when the water concentration decreases. The T _g measurements vs. moisture content may be used for cellulose crystallinity index determination.     

Determination of manganese in natural waters by atomic absorption spectrometry with a carbon tube atomizer.

A method is described for the accurate and precise determination of alumina and silica in bauxites with the aid of a ²²⁷Ac-Be isotopic neutron source with a total neutron output of 10⁸ n s^-1. Three ores can be analysed in triplicate within 4 h, including the determination of the natural radioactivity of the ores. Samples are pellets pressed from a mixture of 4.5 g of powdered bauxite and 0.9 g of a wax as pelleting agent. The special flux distributions of the source allow irradiations at very different fast-to-thermal flux ratios without cadmium neutron absorbers. The drying and water re-uptake of bauxite and the natural radioactivity in these ores are discussed. The method was tested with several certified standards. A relative precision of 0.7% for the alumina determination was obtained for triplicate analyses. Vanadium is the only interfering element, the concentration of which should be determined separately or estimated; a correction procedure is given.     

The Ambiguity of the Viscometric Method for the Deter-Mination of Dextranase Activity

Abstract

In earlier studies it was found that the tissue pellets of Avena seedlings decrease the viscosity of dextran solutions. By the use of direct methods for investigating the breakage of these molecules, it is shown that the lowering of viscosity of dextran solutions under the influence of tissue pellets of Avena coleoptiles is not due to an intramolecular process of molecular breakage (dextranase-like activity) but rather to an intermolecular process of still unknown nature. This conclusion is supported by the finding that solutions of entirely different macromolecules than dextrans are also affected by the tissue pellets. The observed changes in viscosity can therefore not be due to dextranase activity and the viscometric method for the determination of this activity is clearly ambiguous.     

Simple Infrared Cell for Corrosive Gases

Abstract

A simple infrared cell that can be used for corrosive gases is described. The cell consists of a Kel-F tube with silver chloride windows sealed on with Kel-F wax. Evacuation of the cell to 10^?5 mm is possible.     

X-ray fluorescence determination of total sulfur in fly ash

Standard addition, double dilution and standard calibration were used for x-ray fluorescence (XRF) determinations of sulfur in fly ashes. Samples were analysed as pellets prepared by mixing with acrylate copolymer or with microcrystalline cellulose (in the case of the double dilution method). Lithium sulfate was used for the standard addition method and also as standard with known sulfur content for the double dilution method. Fly ashes analysed by optical emission spectrometry with an inductively coupled plasma (ICP-OES) were used as standards for the standard calibration XRF method. Sulfur was determined in the range of ca. 10^–1–10⁰ % S. For the fly ashes from the North-Bohemian brown coals, the differences between the XRF determinations and the ICP-OES determinations ranged from ca. 1.4 to 10% rel. and precision (repeatability) was better than 10% (RSD). The standard calibration method is suitable for routine analyses of real samples of similar nature. The methods of standard addition and double dilution are rather laborious in sample preparation compared with the standard calibration. Received: 27 October 1998 / Revised: 5 March 1999 / Accepted: 11 March 1999     

A Simple Approach for Removal of Carbaryl and Its Monitoring in Water Matrices

Abstract

Carbaryl, 1-napthyl N-methyl carbamate, is an extremely, broad spectrum, contact action insecticide having wide acceptance because of its low mammalian toxicity and less persistent nature. Because Carbaryl is widely used in monsoon season, it finds its way into aquatic environment.

The feasibility of Carbaryl removal by alum coagulation, was checked and found to be suitable for 98% removal of Carbaryl along with efficient turbidity removal in water matrices. The low level monitoring of Carbaryl was performed by spectroscopic technique.     

Supercritical fluid chromatography of industrial paraffins and waxes

Summary The application of capillary SFC for SIMDIST investigations of paraffins and waxes is reported. Pressure, density and temperature of the mobile phase are optimized to obtain high chromatographic resolution of complex mixtures of industrial products. Isothermal linear pressure programming and asymptotic pressure and density programming are used in the range from 15 to 35 MPa in the isothermic mode above 100°C. SFC chromatograms of natural and synthetic paraffins, microcrystalline wax and candle wax are compared. The retention behaviour of paraffin mixtures and waxes has been investigated on methyl/phenyl and biphenyl capillary columns. The polarity of the stationary phases influences the absolute retention time more than it influences the chromatographic resolution.     

Cadmium Preconcentration from Aqueous Environmental Samples Using Microcrystalline Phenolphthalein Modified by Crystal Violet

Abstract

The present work describes a novel method for cadmium preconcentration and separation with microcrystalline phenolphthalein. Phenolphthalein as an extractant modified by crystal violet was originally applied to cadmium extraction from aqueous solution. Cadmium(II) as CdI₃ ^? and CdI₄ ^2? can associate with the cationic crystal violet (CV⁺) forming water‐insoluble ion‐association complexes (CdI₃ ^?) · (CV⁺) and (CdI₄ ^2?) · (CV⁺)₂, which are quantitatively adsorbed on microcrystalline phenolphthalein over the pH range from 1.0 to 6.0. All experimental parameters necessary for successful preconcentration and separation have been investigated and optimized. The study shows that common metal ions, such as Zn(II), Fe(II), Co(II), Ni(II), Mn(II), Cr(III) and Al(III), cannot interfere with cadmium extraction in this microcrystalline system by controlling acidity. The extraction can be accomplished in 15 min. The interaction between CdI₃ ^?and CdI₄ ^2? and CV⁺ plays an important role in the extraction process. The reported method was successfully applied to the preconcentration and separation of cadmium in synthetic samples and real samples with satisfactory results. The results proved that it is an efficient and attractive technique for cadmium preconcentration and separation at trace level.     

Determination of Copper by Atomic Absorption Spectrophotometry After Solid-Liquid Separation by Adsorption of its 1-Nitroso-2-Naphthol Complex onto Microcrystalline Benzophenone

ABSTRACT

A sensitive method for the determination of trace copper by preconcentration and adsorption of its 1-nitroso-2-naphthol complex onto the microcrystalline benzophenone has been developed. Several experimental conditions such as the pH of the solution, the quantities of 1-nitroso-2-naphthol and benzophenone, and the stirring time were optimized for effective separation. Trace copper in a 100 ml water sample was chelated with 2.0 ml of 0.050 M 1-nitroso-2-naphthol at pH 8.0. The solution was heated to 30 °C, stirred vigorously for 10 minutes to adsorb the copper complex quantitatively onto 0.20 g benzophenone. After the microcrystalline benzophenone adsorbed copper complex was filtered and dissolved in acetone, the content of copper was determined by flame atomic absorption spectrophotometry. The interfering effects of concomitant ions were investigated and almost eliminated. The detection limit and the determination limit of this method were 6.9 ngml^?1 and 22.9 ngml^?1, respectively. Recoveries of 103.7 % and 94.2 % were obtained in a tap water and a brass sample, respectively. In the determination of copper in real samples, the values obtained by this proposed method were close to those by GF-AAS.

Based on these experimental results, it is supposed that this method can be applied to the determination of copper in real samples.     

A Study on the Preparation,Structure, and Properties of Microcrystalline Cellulose

Abstract

The preparation, structure, and properties of microcrystalline cellulose (MCC) from rice straw were investigated by IR, x-ray, viscometry, polarizing microscope, SEM, etc. The results are as follows:

1. The leveling-off degree of polymerization (LODP) obtained from rice straw is about 80–150. The dimensions of MCC granules are 20–30 μm length, 0.5–0.8 μm thick, and the crystallinity is about 80%.

2. The aqueous suspension of a certain concentration of MCC can form a gel under the effect of shear force. The viscosity of MCC gel increased with an increasing content of MCC in water. A sharper increase of viscosity occurred in the 3–6% range.

3. The addition of one or two valence salts into the MCC gel increased the viscosity.

4. The viscosity of MCC gel has its maximum value at pH 8.

5. The MCC gel as an emulsifying agent can form a stable emulsion in the oil/water system when the ratio of oil/water is below 6/4.     

Determination of Major and Minor Elements in Granite by Inductively Coupled Plasma and X-ray Fluorescence Spectrometry

Abstract

The development and evaluation of an analytical method for the determination of major and minor elements in granite by ICP-AES and XRF are described. The method applies a standard addition method to generate calibration standards for XRF measurements by ICP-AES from samples to be analyzed. Reliable results were obtained by using simple versions of ICP and XRF, and combined with the pressed-powder pellets for sample preparation. Least squares data for parameters measured by this method vs. reported value for a granite standard reference material gave a slope of 1.002 ± 0.005 and an intercept of -0.029 ± 0.07. The coefficients of variation vary between 0.53% for the largest oxide and 8.3% for the lowest oxide.     

Phase transition and elastic constants of 4-n-octyl-4′-cyanobiphenyl (8CB) obtained using the light-scattering anisotropy of turbidity

Abstract

A light-scattering technique was used to study the anisotropy of turbidity and the three elastic constants K ₁, K ₂ and K ₃ of 8CB as a function of temperature and sample thickness. The turbidity was measured in the nematic and schematic A phases at sample thicknesses l of 0.02, 0.04, 0.1 and 0.2 cm. The effect of the smectic-like (cybotactic nematic) order was observed near the smectic A-nematic phase transition. Owing to the surface-enhanced cybotactic order, evaluation of the elastic constants and order parameter was possible only from the turbidity data at l = 0.2 cm. From the divergence of both K ₂ and K ₃ near T_{S A N} we estimated an average critical exponent value v of 0.65, suggesting that S_A-N in 8CB is a second-order phase transition. The magnetic-field quenching of director fluctuations showed observed effects on the order of magnitude of the temperature dependence of the turbidities, elastic constants and order parameter.     

GPC Of Poly(N-Vinylacetamide) on Silanized Porous Glass in DMF and DMF/LiBr

Abstract

Samples of poly(N-vinylacetamide) were characterized by exclusion chromatography on silanized porous glass columns in DMF and DMF + 0.01M LiBr. Chromatograms obtained in pure DMF were very different in appearance from those observed using DMF + 0.01M LiBr. It is proposed that solutions of the polymer in the pure solvents form stable microcrystalline aggregates leading to the appearance of exclusion limit peaks for the higher MW samples. Strong ion-dipole interactions between the polymer and LiBr prevent the formation of such aggregates, resulting in more normal chromatographic behavior.     

Radiolysis and corrosion of238Pu-doped UO2 pellets in chloride brine

Deaerated 5 M NaCl solution is irradiated in the presence of UO₂ pellets with α-radiation from²³⁸Pu. Experiments are conducted with²³⁸Pu doped pellets and others with²³⁸Pu dissolved in the brine. The radiolysis products and yields of mobilized U and Pu from the oxidative dissolution of UO₂ are determined. Results found for radiolysis products and for the oxidation/dissolution of pellets immersed in Pu containing brine are similar to results for Pu doped pellets, where the radiation chemical processes occur only in the liquid layer of some 10 σm thickness adjacent to the pellet. The yield of radiolysis products is comparable to earlier results, that of mobilized U from the pellets is < 1% of the total amount of oxidized species. Thus, the radiation chemical yield (G-value) for mobilized hexavalent U is < 0.01 ions/100 eV. In spite of the low radiation yield for the corrosion, the rate of UO₂dissolution is higher than expected for the concentrations of long-lived oxidizing radiolysis compounds found in the solutions.     

Nelumbo nucifera leaves as source of water-repellent wax: Extraction through polar and non-polar organic solvents

Nelumbo nucifera leaves are rich source of natural wax possessing super-hydrophobic properties. It provides protection to them from ecological turbulences and climatic wear and tear. In this study, various experiments have been conducted to observe the yield of extraction and the determination of various functional groups, which are present in natural wax, derived from Nelumbo nucifera leaves. The natural wax has been extracted from lotus leaves through non-polar (hexane) and polar (ethanol) solvent via different extraction methods. The superhydrophobic wax has been successfully extracted with hexane. Whereas, ethanol did not extract the water-repellent wax of lotus leaf. Considering the cumulative amount, i.e. (desired + undesired), the maceration shows the extraction of 2.9% (%w/w, through hexane) and 10.2% (%w/w, through ethanol), while it was found 2.5% (%w/w, cycle period 15 min) and 9.0% (%w/w, cycle period 26 min) respectively, in case of Soxhlet extraction technique. For this specific case of natural wax recovery from biomass (lotus leaf), the maceration (traditional method) resulted a little bit superior extraction yield in comparison to the Soxhlet extraction method for extraction of crude wax. In the case of non-polar solvent (hexane), an extraction yield of 1.97% (%w/w) through maceration method was observed while in the case of non-polar solvent (ethanol), an extraction yield of 1.62% (%w/w) through Soxhlet extraction was observed. The TLC analysis on both types of extracts was performed. For the detection of various hydrocarbon chains in the crude wax extracts, FTIR was also performed. Topography of wax surface and wax-coated waterproof fabric was compared through SEM.