Showing papers in "Acta Chimica Slovenica in 2005"

Characterization of phenol-formaldehyde prepolymer resins by in line FT-IR spectroscopy

Abstract: Different resol phenol-formaldehyde prepolymer resins have been synthesized with different formaldehyde / phenol ratios. The phenolic resin composition depends on monomer ratio, catalyst, reaction conditions, and residual free monomers. Temperature and pH conditions under which reactions of phenols with formaldehyde are carried out have a profound effect on the characteristics of the resulting products. Three reaction sequences must be considered: formaldehyde addition to phenol, chain growth or prepolymer formation and finally the crosslinking or curing reaction. Two prepolymer types are obtained depending on pH, novolacs in an acidic pH region whereas resols by alkaline reaction. Resol resins are synthesized with a molar excess of formaldehyde (1

Equilibrium sorption study of Al3+, Co2+ and Ag+ in aqueous solutions by fluted pumpkin (Telfairia occidentalis HOOK f) waste biomass

Abstract: An ensemble of equilibrium sorption techniques was combined to study the influence of ionic radius on the sorption characteristics of Al 3 + , Co 2 + and Ag + by fluted pumpkin waste biomass. The experimental results were analyzed in terms of five two-parameter adsorption isotherm equations - the Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Flory-Huggins isotherms. According to the evaluation using Langmuir equation, the monolayer sorption capacity obtained was 16.98 mg/g, 10.34 mg/g and 8.03 mg/g for Al 3 + , Co 2 + and Ag + respectively. The data further showed that, the Freundlich and Langmuir isotherms described the data appropriable than Temkin, Dubinin-Radushkevich and Flory-Huggins isotherms. The result showed that fluted pumpkin waste could be used for the removal of Af + , Co 2 + and Ag + from wastewater and ionic radius influences the rate of metal ion migration to the biomass surface and the adsorption intensity of the metal.

Inorganic materials synthesis - : a bright future for ionic liquids?

Abstract: Materials Science goes back to prehistoric times, where people started to utilize rocks, bones, leather, and other things they found in Nature to fabricate tools and clothing. Later, this knowledge evolved and metals, alloys, ceramics, and fabrics replaced the older materials with inferior properties. In historic times, the knowledge of materials and processing improved further and more sophisticated materials for more sophisticated (or fashionable) applications became available. An example of a historic high-tech material is Damascus Steel, which is responsible for the extraordinary sharpness of historic sword blades from the Middle East. No European blacksmith at the time was able to produce anything that came even close to the blades of the Damascus swords. In the mid 19 century, the knowledge of how to make those blades apparently got lost. Only very recently, Verhoeven and colleagues have been able to fabricate blades that appear to be comparable to the historic materials. It turns out that many of the superior properties of the metal blade come from its highly sophisticated processing, microstructure, and chemistry, including a variety of impurities like C, V, Mo, Cr, Mn, and Nb. Much more recently, “nano” has become the new hot topic in materials science. The common theme here is always “size matters” and over the last decades, researchers have developed exciting new materials with unique and tunable properties. For example, Brust et al. have in the early 1990s triggered an immense interest in gold nanoparticles, which is reflected in the dramatic increase in publications and patents with this topic, Figure 1. The interest in nanostructured inorganic and organic/inorganic composite materials has further grown to now include other metallic, alloy, and inorganic nanoparticles, assemblies, 2D and 3D structures, and many more.

Equilibrium and Kinetic Study of Reactive Dye Brilliant Red HE-3B Adsorption by Activated Charcoal

Abstract: The commercially powdered activated charcoal was used for the sorption of reactive dye Brilliant Red HE-3B from aqueous solutions. The effect of solution pH, initial dye concentration, temperature and sorption time on dye removal was studied. The equilibrium sorption isotherms have been analysed by the linear, Freundlich and Langmuir models. The Langmuir isotherms have the highest correlation coefficients. The apparent thermodynamic parameters were calculated and the obtained values support the conclusion that the reactive dye molecules sorbs by entropy-driven, endothermic process. The kinetic of the sorption was analysed using the pseudo-first order and pseudo-second order kinetic models. The data showed that the second-order equation was the more appropriate, which indicate that the intraparticle diffusion is the rate limiting factor.

Spectroscopic Study of Polyaniline Emeraldine Base: Modelling Approach

Abstract: The polymerization of aniline by Cu(II) montmorillonite was studied using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. Experimental spectra were compared with that calculated by AMI, PM3, PM5, MINDO, Hartree-Fock, HF/6-31g(d), as well as Density Functional Theory, BLYP/DZVP and B3LYP/6-31g(d,p). Furthermore, the final heat of formation is studied as a function of temperature. Results indicate that, for aniline B3LYP/6-31G(d,p) calculated frequencies are in a good agreement with experimental data, while HF/6-31G(d) is the optimal in case of polyaniline. The vibrational calculations of a four-ring unit (emeraldine base: EB) are believed to be a good representation of the polyaniline at Cu(II)-montmorillonite. The final heat of formation is a function of polymerization and changed from aniline monomer to five ring repeat unit of polyaniline structure.

Selectfluor (f-teda-bf4) as a versatile mediator or catalyst in organic chemistry

Abstract: Selectfluor F-TEDA-BF 4 1(1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetra-fluoroborate)) is not only one of the most valuable reagents for electrophilic fluorination but also a versatile mediator or catalyst for various other functionalisations of organic compounds. Its application for selective and effective iodination, bromination, chlorination, nitration and thiocyanation of a comprehensive range of organic compound is reviewed. Benzylic functionalisation of hexamethylbenzene mediated with F-TEDA-BF 4 in the presence of various sources of nucleophiles is described and a method for the synthesis of para-quinols or para-quinol ethers emphasised. F-TEDA-BF 4 is also useful for the promotion of allylstannation of aldehydes and imines, cleavage ofp-methoxy-benzylidene (PMP), tetrahydropyranyl (THP) or 1,3-dithiane protection, and rearrangements of bicyclic iodides, as well as for catalysis of the regioselective ring opening of epoxides or [4+2] cycloaddition reactions between imines and cyclic enol ethers.

Sub) micron CaF2 cubes and hollow rods from ionic liquid emulsions

Abstract: Uniform CaF 2 cubes and rods with a well-defined crystal habit have been grown from emulsions of an ionic liquid (IL) in aqueous CaCl 2 solutions via the hydrolysis of the PF 6 - counterion of the IL. Intriguingly, at high IL contents, hollow CaF 2 rods form, which has not been observed before. The rods can reach lengths up to over ten micrometers and widths of up to ca. 2.5 μm. Furthermore, the surface of the IL droplet has a strong influence on the nucleation efficiency of the precipitating mineral.

The Adhesion Phenomena in Polypropylene/Wollastonite Composites †

Abstract: Modification of polypropylene (PP) with wollastonite fillers was investigated in this paper. Three types of different silane pretreated wollastonite mineral filler were used for preparation of binary PP/wollastonite composites. The composite samples were homogenized in a Brabender Plasti-Corder kneading chamber and compression moulded into plates on a laboratory press. The adhesion between the wollastonite fillers used in this study and the PP matrix was predicted on the basis of the calculated adhesion parameters (work of adhesion, interfacial free energy and spreading coefficient) obtained by the surface free energy of pure materials. The contact angle method was used to determine surface free energy of components. The obtained values of adhesion parameters at the interface in the composites were correlated with mechanical properties as well as morphology observations of corresponding composites and were proved to be in relatively good agreement with the mechanical property measurements. Stronger adhesion in investigated composites has reflected in higher yield stress and tensile strength at break but in lower elongation at break and impact resistance.

Ecofriendly synthesis of novel antifungal (thio)barbituric acid derivatives

Abstract: An expeditious solventless synthesis of novel Mannich bases of thiobarbiturates and barbiturates using montmorillonite clay under microwaves are herein described. This methodology eliminates the use of excess of solvent during the course of reaction. The reaction time is brought down from hours to minutes along with yield enhancement. The rate enhancement and high yield is attributed to the coupling of MWS with solventless conditions. Further, the role of montmorillonite K-10 clay is studied in the reaction and it is concluded that microwave assisted montmorillonite clay catalyzed reaction is the best in terms of catalysis as well as reaction and yield. All the compounds synthesized were screened for their antifungal activity against A. niger and A. flavus and found to possess good activity.

Synthesis of some biologically active pyrazoles and C-nucleosides

Abstract: (5,6-Dihydronaphtho[1',2':4,5]thieno[2,3-d]pyrimidin-11-yl)-hydrazine (1) was used as a precursor for preparation of some novel 1-(5,6-dihydronaphtho[1',2':4,5]thieno[2,3-d]pyrimidin-11-yl)-pyrazole derivatives 2-7. Also,some acyclic and cyclic C-nucleosides 8 and 10-12 were prepared by treating compound 1 with aldoses. Some of the prepared products showed potent antimicrobial activity.

The effect of annealing on structural, optical and electrical properties of nanostructured tin doped indium oxide thin films

Abstract: A low level tin doped indium oxide, ITO, (ca. 10 w % SnO 2 ) thin films were prepared on glass substrate by electron beam technique. Deposited films with deposition rate of 0.1-0.25 nm s - 1 were annealed at different temperatures from 250 to 550 °C in air. The thin films were characterized using low and high angle X-ray diffraction and UV-visible spectroscopy. The lattice constant and the grain size of ITO thin film were 10.118 A and 36 nm, respectively. UV-visible transmission spectra confirmed the formation of high quality ITO nano-particles. These low level tin doped indium oxide thin films showed higher transparency over the visible wavelength region (ca. 95%) than those of already reported with higher level tin doped indium oxide thin films deposited at 350 °C. The transmission data were used for direct and indirect optical band gap calculations ca. 3.6 and 3.8eV, respectively. The refractive index and porosity of ITO films annealed at different temperature were calculated from measured transmittance data. The results showed that the refractive index of thin films increased with increasing annealing temperature, but the porosity of ITO thin films showed opposite trend. The lowest resistivity (2.9 ×10 - 6 Ω m) and highest porosity (40.1%) were obtained for the annealed film at 550 °C.

Wood liquefaction using dibasic organic acids and glycols

Abstract: Liquefaction of Central European hardwoods was performed using a number of different glycols in combination with dibasic organic acids and a minor addition of ortho-phosphoric acid as a catalyst. The reaction carried outat 190 °C resulted in liquefaction of 15-56% of the original wood. The best effects were achieved using propylene glycol as the solvolytic reagent and maleic anhydride as the the acidic reagent. The unsolubilized solid remains were investigated using scanning electron microscopy. The liquefaction product examined by size exclusion chromatography and infrared spectroscopy was composed of low molar mass oligomeric polyesters.

Sequential determination of 241Am, 237Np, pu radioisotopes and 90Sr in soil and sediment samples

Abstract: A sensitive and reliable method for the simultaneous determination of 2 4 1 Am, 2 3 7 Np, plutonium radioisotopes and 9 0 Sr in soil and sediment samples is described. Analysis involves leaching of the samples in conc. HNO 3 , followed by radiochemical separation and purification. The radiochemical procedure begins with separation of 2 4 1 Am/ 9 0 Sr, plutonium radioisotopes and 2 3 7 Np by anion exchange chromatography. 2 4 1 Am and ""Sr from the combined effluent are separated using TRU resin and Sr resin. Counting sources for alpha spectrometric measurements were prepared by the microcoprecipitation technique. Radiochemical yields were determined using 2 4 3 Am 2 3 9 Np and 2 4 2 Pu tracers. Strontium recovery was determined gravimetrically and Sr counting sources were analysed by liquid scintillation counting. The method was successfully tested by analysis of six reference materials and on two sediment samples with high activities of the selected radionuclides. The results were compared with reference and literature values.

Flow injection spectrophotometric system for N-acetyl-L-cysteine determination in pharmaceuticals

Abstract: A flow injection system with spectrophotometric detection is proposed for determining N-acetyl-L-cysteine in pharmaceutical formulations. In this system, N-acetyl-L-cysteine was oxidized by Fe(III) and the Fe(II) producedis spectrophotometrically monitored as Fe(II)-1,10-phenantroline complex at 510 nm. Under the optimum analytical conditions, the linearity of the calibration curve for N-acetyl-L-cysteine ranged from 3.5×10 - 6 to 4.3×10 - 4 M. The detection limit of 6.3×10 - 7 M and recoveries between 98.5 to 110% were obtained.

Novel Calcium Sensor Based on (2-(2-Hydroxyphenyl)imino)-1,2-diphenylethanone

Abstract: In this work, a novel calcium PVC-based membrane sensor based on 2-[(2-hydroxyphenyl)imino]-1,2-diphenylethanone (HD) as a new ionophore is presented. The sensor displays a linear dynamic range between 1.0×10 - 1 and1.0×10 - 6 M, with a near Nernstian slope of 28.5 ′ 0.5 mV per decade and a detection limit of 8.0 x 10 - 7 M. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzene, 5% sodium tetraphenyl borate and 3% HD. The potentiometric response of the proposed electrode is independent of the pH of the solution in the pH range of 4.0-11.5. The sensor possesses the advantages of short conditioning time, fast response time (<20 s), and especially, very good selectivity towards alkali and alkaline earth, and some mono, di and trivalent cations, such as Li + , Na + , K + , Mg 2 + , Sr 2 + , Ba 2 + . Ag + , Cu 2 + , Al 3 + , La 3 + and Ce 3 + ions. The electrode can be used for at least 10 weeks without any considerable divergence in the potentials. It was used as an indicator electrode in potentiometric titration of Ca(II) ions with EDTA.

Combination of Fenton and biological oxidation for treatment of heavily polluted fermentation waste broth

Abstract: The aim of our work was to study the biotreatability of heavily polluted pharmaceutical fermentation broth (COD value of 124,500 mg.L - 1 ) as well as application of Fenton oxidation for effective pretreatment. Because waste broth expressed biodegradability (BOD 5 /COD ratio was 0.40), biological treatment was the first choice. At the same time, in preliminary ready biodegradability assessment test, diluted broth degraded 65% as well it was not toxic to mixed bacterial culture of activated sludge. Further experiments in pilot laboratory biological treatment plant confirm acceptable treatment efficiency up to 0.01 vol% of the broth added (76%). However, we had considered additional pretreatment method to be able to enhance biotreatability. Fenton procedure was optimised in batch reactor using different concentrations of Fe 2 + , H 2 O 2 , temperatures (40/45 °C), as well as different retention times (up to 30 minutes). The highest treatment efficiency reached only 44% according to COD, but ready biodegradability of the sample increased (82%). Fenton oxidation was confirmed as possible method for pretreatment of broth, because it slightly enhanced biodegradability, it reduced organic pollution and formed products were non-toxic. We have focused our future work into a study on optimisation of applied procedure for improving biotreatability of the investigated broth.

Tracer Studies on Sr Resin and Determination of 90 Sr in Environmental Samples

Abstract: In this work various tracer experiments were performed to investigate the elution behaviour of some radionuclides on Sr resin, matrix effects of calcium and potassium and the resin capacity for strontium. None of the studied radionuclides interfered with the separation of strontium since all were washed out with 3M HNO 3 before the elution step with water, except barium. Barium and strontium were separated using 8M HNO 3 . The maximum resin capacity for strontium was 8.1 mg of Sr/g of Sr resin. Up to 2 g of calcium and 200 mg of potassium can be loaded on the Sr column (3 g Sr.spec) without decrease in strontium recovery. The separation procedure using Sr resin was tested on soil samples spiked with 9 0 Sr standard solutions and on reference materials. All results obtained by this method gave good agreement. Counting sources were prepared by weighing SrC 2 O 4 on a planchet. The 9 0 Sr content was measured with a proportional gas flow beta counter after secular equilibrium between 9 0 Sr and 9 0 Y was reached. The chemical recovery was determined gravimetrically and was always higher than 80%.

Presence of dioxins in textile dyes and their fate during the dyeing processes

Abstract: Considerable levels of highly toxic polychlorinated dibenzo-p-dioxins (PCCDs) and polychlorinated dibenzofurans (PCDFs) were determined in two among the six analysed disperse textile dyes. The dioxin homologue profile of these dyes was similar to that found in some environmental and industrial samples, connected with the textile industry. Dyes contaminated with dioxins were further used in industrial polyester dyeing processes at laboratory scale. We observed the changes in dioxin contents, dioxin transformations and their distribution during the textile dyeing process. After the dyeing and textile finishing processes the content of dioxins was up to fifteen times higher. More than 85% of the total dioxin content was found in dyed polyester. Other 15% was discharged with waste dye bath. Our results confirmed that the presence of dioxins in some textile dyes may be a significant source regarding human exposure and environmental contamination.

Group theory for tetramethylethylene

Abstract: The maturated and unmaturated groups have been introduced by S Fujita who used them in the markaracter table and the Q-conjugacy character table of a finite group Fujita introduced more concise forms called the Q-conjugacy characters with integer-valued of the irreducible characters of finite groups and applied his results in this area of research to enumerate isomers of molecules In this paper using GAP program all integer-valued characters of the full non-rigid group (f-NRG) of tetramethylethylene (2,3-dimethylbut-2-ene) is calculated by the Q-conjugacy relationships It is shown that this group has 29 dominant classes (similarly, Q-conjugacy characters) such that 16 of them are unmaturated (similarly, Q-conjugacy characters such that they are the sum of two irreducible characters) Then the markaracter table and Q-conjugacy character table of the f-NRG of tetramethylethylene are derived for the first time

Application of the new solvation theory to reproduce the enthalpies of transfer of LiBr, tetrabutylammonium bromide and tetrapentylammonium bromide from water to aqueous acetonitrile at 298 K

Abstract: The enthalpies of transfer, ΔH θ t , of LiBr, tetrabutylammonium bromide, n-Bu 4 NBr, and tetrapentylamonium bromide, n-Pen 4 NBr, from water to aqueous acetonitrile solvent system are reported and analyzed in terms of the new developed solvation theory. The solvation parameters obtained from the analyses indicate that the net effect of tetraalkylammonium bromides on solvent structure is a breaking of solvent-solvent bonds and thus tetraalkylammonium bromides is preferentially solvated by acetonitrile. Preferential solvation of tetraalkylammonium bromides by acetonitrile is consistent with hydrophobisity of these compounds. LiBr is preferentially solvated by water.

Simultaneous Determination of Salicylamide and Paracetamol by Spectrophotometric H-Point Standard Addition Method and Partial Least Squares Regression

Abstract: Simultaneous spectrophotometric determination of salicylamide and paracetamol by H-point standard addition method (HPSAM) and partial least squares (PLS) calibration is described. The results showed that simultaneous determinations could be performed with the ratio 0.2:5-20:1 for salicylamide - paracetamol. A partial least - squares multivariate calibration method for the analysis of binary mixtures of paracetamol and salicylamide was also developed. The total relative standard error for applying the PLS method to 10 synthetic samples in the concentration range 0-60 μg mL - 1 salicylamide and 0-30 μg mL - 1 paracetamol was 5.1%. Both the proposed methods (PLS and HPSAM) were successfully applied to the determination of salicylamide and paracetamol in pharmaceutical preparations.

NMR multi-scale description of ionic conductivity mechanisms inside polymer electrolytes

Abstract: Solid Polymer Electrolytes are obtained by dissolving an alkali metal salt inside poly(ethylene oxide) based materials. The properties of these materials are strongly related to the behavior of the different active species : solvent (polymer), cation, and anion. In this paper, we compare various NMR techniques capable of deciphering different aspects of these new materials : the structure and dynamics of the polymer, the cations and anions as well as the supramolecular interactions between these different species. These data are very useful for understanding the conductivity mechanisms inside various families of PEO-based materials (nanocomposites, block oligomers and copolymers, and liquid crystals) developed by our group.

Genetic algorithm optimized neural networks ensemble for estimation of mefenamic acid and paracetamol in tablets

Abstract: Improvements in neural network calibration models by a novel approach using neural network ensemble (NNE) for the simultaneous Spectrophotometric multicomponent analysis is suggested, with a study on the estimation of the components of an analgesic combination, namely, Mefenamic acid and Paracetamol. Several principal component neural networks were trained with the Levenberg-Marquardt algorithm by varying conditions such as inputs, hidden neurons, initialization and training sets. Genetic algorithm (GA) has been used to develop the NNE from the trained pool of neural networks. Subsets of neural networks selected from the pool by decoding the chromosomes were combined to form an ensemble. Several such ensembles formed the population which was evolved to generate the fittest ensemble. Ensembling the networks was done with weighted average decided on the basis of the mean square error of the individual nets on the validation data while the ensemble fitness in the GA optimization was based on the relative prediction error on unseen data. The use of computed calibration spectral dataset derived from three spectra of each component has been described. The calibration models were thoroughly evaluated at several concentration levels using 104 spectra obtained for 52 synthetic binary mixtures prepared using orthogonal designs. The Ensemble models showed better generalization and performance compared to any of individual neural networks trained. Although the components showed significant spectral overlap, the model could accurately estimate the drugs, with satisfactory precision and accuracy, in tablet dosage with no interference from excipients as indicated by the recovery study results. The GA optimization guarantees the selection of best combination of neural networks for NNE and eliminates the arbitrariness in the manual selection of any single neural network model of a specific configuration, thus maximizing the knowledge utilization

Syntheses of 4-(2-naphthyl)pyridine derivatives from DDNP

Abstract: The ethylidenemalononitrile side-chain in {1-[6-(dimethylamino)-2-naphthyl]ethylidene}malononitrile (DDNP) was elaborated into a substituted pyridine ring in a two-step process. In this manner formal derivatives of a molecular probe (1-{6-[(2-fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile (FDDNP), which is successfully applied in positron emission tomography to diagnose Alzheimer's Disease, were prepared. Chloroimidate intermediate in reaction of a nitrile group with HCl in alcoholic solution was trapped in the form of 2-chloro-4-[6-(dimethylamino)-2-naphthyl)nicotinonitrile, thus proving its existence in the Pinner synthesis. The structure of 2-methylamino derivative was also proven by X-ray analysis.

Semi-Interpenetrating Polymer Networks with Varying Mass Ratios of Functional Urethane and Methacrylate Prepolymers †

Abstract: The morphology and mechanical properties of grafted semi-interpenetrating polymer networks (SIPNs), based on ester-urethane (PU) prepolymers and methacrylate (PM) prepolymers were studied with regard to the PU and PM mass ratio and with regard to the concentration of functional groups. The SEM micrographs, glass transition temperature shifts of the individual constituents and mechanical properties of the studied SIPNs show that their miscibility is enhanced by the interaction of complementary functional groups which also stabilize the mixture at elevated temperatures. However, enhanced miscibility was observed only in SIPNs with PU component in excess, while in SIPNs with the PM component in excess miscibility was poor. Enhanced miscibility in the SIPN with functional groups having a PU/PM mass ratio of 0.5/0.5 was ascribed to the most intense interaction between functional groups at this PU/PM ratio. Mechanical properties (Young's modulus and tensile strength) of SIPN films were defined by the polymer component forming the matrix. They were significantly influenced by the interaction between functional groups.

Applications of Boronic Acids in Selective C-C and C-N Arylation of Purines

Abstract: Substituted purine derivatives have broad biomedical value as therapeutics, and have attracted great interest as molecular tools and probes for investigating biological systems. The modification of purines with aryl or heteroaryl substituents dramatically alters conformational preferences, the steric profile, and hydrogen-bonding capacity. The development of new methods for metal-mediated coupling with aryl or heteroaryl halide substrates has greatly expanded the range of synthetically accessible arylpurine derivatives. Arylboronic acids have proven to be extremely effective reagents for the synthesis of arylpurine compounds. Arylboronic acids are stable, versatile, and readily available reagents for metal-mediated C-C and C-N coupling reactions. Coupling reactions resulting in C-C bond formation are catalyzed by palladium and nickel catalysts at positions C 2 , C 6 , and C 8 . Copper mediated N-arylation occurs at positions N 1 , N 2 , , N 7 , and N 9 . These methods are also applicable using solid supported purine substrates. Successful coupling involves careful optimization of catalyst, ligand, base, solvent, and reaction temperature. These methods provide convenient access to structurally unique arylpurine derivatives with applications in drug discovery and chemical biology.

Mspd combined with fast GC for ultratrace analysis of pesticide residues in non-fatty food

Abstract: Matrix solid phase dispersion (MSPD) sample preparation method was combined with fast gas chromatography (GC) to determine pesticide residues of different volatility and polarity at ultratrace concentration level. Apples as representatives of a non-fatty food were chosen as a matrix; they are also a common raw material for baby food production. At fast GC conditions with electron capture detection (ECD) several parameters of MSPD procedure were optimised. Sample is homogenized with sorbent Florisil, pesticides are eluted with the optimised volume of etylacetate. After evaporation of solvent to dryness, reconstitution of the rest to toluene follows and the final extract is injected utilising splitless injection. These optimised procedure leads to recoveries ≥ 90% (at concentration level of 60 μg kg - 1 ) and limits of quantification (LOQs) < 47 μg kg - 1 (except of diazinon) utilizing ECD. Except of dimethoate all LOQs are lower than related maximum residual limits (MRLs) set for commodity apple. Also the possibilities of mass spectrometric (MS) detection were studied. Even at the halfpre-concentration factor LOQs for all pesticides were lower than 10 μg kg - 1 , the MRL for baby food. Acceptable recoveries were obtained even at concentration level of 5 μg kg - 1 (≥ 79%).

Recovery and Purification of Rosmarinic Acid from Rosemary Using Electrodialysis

Abstract: Recovery and purification of rosmarinic acid from rosemary was performed using lab-scale electrodialysis unit. Electrodialysis of rosmarinic acid model solution was performed to validate its applicability for rosmarinic acid separation. Positive influence of ethanol addition on process performances was analysed in the experiments with dried rosemary extract. Under optimum process conditions (addition of 30% ethanol) ion flux reached 5.9 10 - 1 g m - 2 min - 1 , specific energy consumption was 3.9 kWh kg - 1 , and current efficiency achieved 80.1%.

Genotoxicity detection in drinking water by ames test, zimmermann test and comet assay

Abstract: Drinking water of good quality is the primary requirement from public health point of view. Over past two decades, many studies have reported the presence of various hazardous compounds in drinking water that may cause long-term health effects, e.g. gastrointestinal and urinary tract cancers. Sources of drinking water contamination are industrial and agricultural activities, disinfection by-products and transportation. Monitoring of drinking water in Slovenia is based on regular physico-chemical and microbiological assays according to European Community legislation. Since physico-chemical analyses do not provide enough information about biological effects of pollutants, we are studying the possibilities of including biological tests into drinking water monitoring. In the present work we tested three genotoxicity assays with water collected at three different sampling points in Ljubljana drinking water region. The Ames test was performed with and without metabolic activation using bacterium Salmonella typhimurium TA97a, TA100 and TA1535 strains. The same samples were tested with the yeast Saccharomyces cerevisiae strain D7, with and without metabolic activation in Zimmermann test. Parallel genotoxicity evaluation on the samples was carried out as alkaline version of the comet assay performed with human HepG2 cell line. Original and concentrated water samples were tested in all bioassays following the chemical analyses for pesticides and nitrate. There was no indication of genotoxic activity in any of drinking water samples according to Ames and Zimmermann test. On the contrary, the results of the comet assay revealed low genotoxicity in most of the drinking water samples. As only the Comet assay proved to be sensitive enough to detect genotoxicity, we propose to include it in regular biomonitoring of drinking water.

Use of prokaryotic and eukaryotic biotests to assess toxicity of wastewater from pharmaceutical sources

Abstract: Scientific Paper Use of Prokaryotic and Eukaryotic Biotests to Assess Toxicity of Wastewater from Pharmaceutical Sources Jasna Hrenovic, a * Bozidar Stilinovic, a and Lujo Dvoracek b a University of Zagreb, Faculty of Science, Department of Biology, Rooseveltov trg 6,HR-10000 Zagreb, Croatia b PLIVA - Research Institute plc, Prilaz baruna Filipovica 29, HR-10000 Zagreb, CroatiaReceived 09-12-2004 The yeast toxicity test (YTT), based on the inhibition of saccharose fermentation by the yeast Saccharomyces cerevisiae , was evaluated using standard toxicants (copper sulphate, formaldehyde, sodium nitrite, sodium sulphite, phenol and zinc sulphate). Repeated measurements of YTT accuracy with the standard toxicants showed EC 50 values characterized by low standard deviation and coefficient of variation (7.62%). Moreover, the YTT was compared to standard prokaryotic biotests by estimating the toxicity of wastewater from pharmaceutical sources. The toxicity of wastewaters measured by YTT agrees sufficiently with those measured by standard methods of the determination of toxicity such as inhibition of bioluminescence, TTC-dehydrogenase activity, aerobic bacterial growth and anaerobic sludge biogas production. The YTT is a rapid, simple, reliable, sensitive and cost-effective method for presumptive estimations of the toxicity of wastewaters, which could be performed in laboratory as well as in field conditions.