Showing papers in "Acta Chimica Slovenica in 2010"

Tetrabutylammonium Bromide in Water as a Green Media for the Synthesis of Pyrano[2,3-d]pyrimidinone and Tetrahydrobenzo[b]pyran Derivatives.

Abstract: Tetrabutylammonium bromide (TBAB) was used as a green catalyst for the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-d]pyrimidinone derivatives in water as a solvent. Use of nontoxic reaction components, short reaction times, easy work-up and high yields are some important advantages of this method.

Note on the Comparison of the First and Second Normalized Zagreb Eccentricity Indices

Abstract: The conjecture ∑ uv∈E(G) d G (u) 2 / n(G) ≤ ∑ uv∈E(G) d G (u)d G (ν) / m(G) that compares normalized Zagreb indices attracted recently a lot of attention 1-9 In this paper we analyze analogous statement in which degree d G (u) of vertex u is replaced by its eccentricity e G (u) in which way we define novel first and second Zagreb eccentricity indices. We show that ∑ u∈V(G) e G (u) 2 / n(G) ∑ uν∈E(G) e G (u)e G (ν) / m(G) holds for all acyclic and unicyclic graphs and that neither this nor the opposite inequality holds for all bicyclic graphs.

Zeta potential determination of polymeric materials using two differently designed measuring cells of an electrokinetic analyzer.

Abstract: The so-called zeta potential can be determined through electrokinetic measurements and indicates the status regarding surface charges along the interface between solids and liquids. Surface charge gives us information about the condition, quality, and characteristics of a macroscopic surface in the polar medium. In our study the zeta potential was determined using a "SurPASS" electrokinetic analyzer based on the streaming current and streaming potential measurements. The aim of the research was to compare the results of two differently designed measuring cells ("Adjustable Gap Cell" and "Clamping Cell") but operating on the same principle. In order to investigate this problem, the zeta potential was determined for the three polymeric materials: poly(ethylene terephthalate) foil, thin-film polyamide composite membranes for nanofiltration and reverse osmosis. The results obtained with "Clamping Cell" versus "Adjustable Gap Cell" showed differences in zeta potential, where the "Adjustable Gap Cell" gave more reproducible results. One reason for this behaviour could be the different geometries of the streaming channels. A more likely reason is the design of the "Clamping Cell", that requires a sample size larger than necessary for zeta potential determination.

A New Version of Atom-Bond Connectivity Index

Abstract: The atom-bond connectivity index is a recently introduced topological index defined as [Formula: see text], where du denotes degree of vertex u. Here we define a new version of the ABC index as [Formula: see text], where nu denotes the number of vertices of G whose distances to vertex u are smaller than those to other vertex v of the edge e = uv, and nv is defined analogously. The goal of this paper is to study the ABC2 index.

Zinc(II) Thiosemicarbazone Complex As a Ligand Towards Some Transition Metal Ions: Synthesis, Spectroscopic and Antimicrobial Studies.

Abstract: Heterobinuclear complexes have been synthesized by stepwise reactions using the mononuclear complex, [Zn(Tsc)2] • H2O, as a complex ligand towards the metal ions, vanadyl(IV), manganese(II), iron(III), cobalt(II), nickel(II) and copper(II). The complex ligand was synthesized by the reaction of zinc acetate dihydrate with salicylaldehyde followed by the condensation with thiosemicarbazide. The structures of the complex ligand and the prepared complexes were elucidated by elemental analyses, IR, electronic, mass, 1H and 13C NMR spectra as well as molar conductivity and magnetic susceptibility measurements. All the complexes exhibited octahedral geometrical arrangements formulated as [Zn(Tsc)2VO(SO4)(H2O)], [Zn(Tsc)2MCl2(H2O)2] (M = Mn, Fe and Co) and [Zn(Tsc)2Fe(ox)Cl2] except the nickel(II) and copper(II) complexes, [Zn(Tsc)2CuCl(H2O)], [Zn(Tsc)2NiCl2], which have square planar geometries. The complex ligand and some of its heterobinuclear complexes showed antibacterial activity against the sensitive organisms Staphylococcus aureus as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria and antifungal activity against the fungi Candida albicans and Aspergillus flavus.

A novel green chemical route for synthesis of silver nanoparticles using camellia sinensis.

Abstract: The thrust to develop environmental friendly procedures for production of Nanoparticles arises from the very fact that current nanotechnology research uses a lot of chemicals, which are potential threat to both environment and public health Tea (Camellia Sinensis) with its rich source of polyphenolic compounds has been exploited for the reduction and capping of silver nanoparticles (Ag-NPs), making it a complete green chemical route The reduction of Ag + to Ag 0 was observed by the color change from pale yellow to dark yellow The reaction was followed with the help of UV-Visible spectrometer Crystal structure was obtained by carrying out X-ray diffraction studies and it showed face centered cubic (fcc) structure The particle size and morphology were obtained from transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) studies An average particle size of 25 nm silver particles could be obtained using this method and the TEM and SAXS data corroborate with each other

HOMO-LUMO Maps for Fullerenes

Abstract: The HOMO-LUMO map is found to be a useful tool for classifying p-electron configurations of fullerenes and identifying research questions about their adjacency spectra.

On sum-connectivity matrix and sum-connectivity energy of (molecular) graphs.

Abstract: If G is a (molecular) graph with n vertices, and d(i) is the degree of its i-th vertex, then the sum-connectivity matrix of G is the n x n matrix whose (i, j) -entry is equal to 1/root d(i) + d(j) if the i-th and the j-th vertices are adjacent and 0 otherwise. The sum-connectivity energy of a graph G is defined as the sum of the absolute values of the eigenvalues of the sum-connectivity matrix. Some properties including upper and lower bounds for the eigenvalues of the sum-connectivity matrix and the sum-connectivity energy are established, and the extremal cases are characterized.

Self-assembled Polyelectrolyte Nanocomplexes of Alginate, Chitosan and Ovalbumin.

Abstract: Polyelectrolyte complex (PEC) nanoparticles for delivering model protein drug ovalbumin were prepared from two polysaccharide polymers, alginate and chitosan. The parameters influencing the complex formation were characterised using colloid titration in combination with dynamic light scattering. The polyelectrolyte interactions and morphology of the formed complexes were verified by differential scanning calorimetry and scanning electron microscopy, respectively. The PEC formation was predominantly pH- and concentration-dependent. The complexation of ovalbumin with a negatively charged alginate occurred only at a pH below the isoelectric point of the ovalbumin. After the complexation, negatively charged complexes of alginate and ovalbumin were further coated with chitosan. The optimal composition of the PEC, yielding 280 nm sized particles having a zeta potential -40 mV, was determined for alginate:ovalbumin:chitosan in a mass ratio 1: 1: 0.1, respectively, giving their final concentration 0.5: 0.5: 0.05mg/ml. The loading of ovalbumin in the PEC depended on the initial amount of ovalbumin used to produce the PEC, and ranged from 7-38% for different formulations, however, the association efficiency remained pretty similar for all formulations, i.e. 80-85%. Mild formulation conditions, nanometre-sized particles, and a high protein association efficiency are promising factors towards the development of a delivery system for proteins.

Patterns of ring current in coronene isomers.

Abstract: The ipsocentric pseudo-π model is used to predict maps of induced current density for isomeric variations of coronene in which the central hexagonal ring is surrounded by 5, 6, and 7-membered rings. All isomers in the set are predicted to support strong diatropic perimeter ring currents, thereby conforming to the magnetic criterion of aromaticity.

Randic index, irregularity and complex biomolecular networks

Abstract: A new formulation of Randic index is carried out as a minimization of a quadratic form which involves the Laplacian matrix of a graph. Using this formulation it is easy to realize that Randic index is useful in defining a new index of irregularity, which is then formulated here. A new context for the study of irregularity of graphs is advanced as a necessity for studying complex (biological) networks. We analyze both Randic and irregularity indices for random networks with Poisson and power-law degree distributions.

Synthesis, Characterization and Antimicrobial Study of Novel 4-{[(8-Hydroxyquinolin-5-yl)methyl]amino}benzenesulfonamide and Its Oxinates.

Abstract: A novel 4-{[(8-hydroxyquinolin-5-yl)methyl]amino}benzenesulfonamide (HQMABS) was synthesized by optimized reaction of 4-aminobenzenesulfonamide with 5-chloromethyl-8-hydroxyquinoline hydrochloride (CMHQ). Various oxinates of HQMABS were also prepared using Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) metal salts. All compounds were analyzed by physicochemical, thermogravimetric and spectroscopic techniques. Antimicrobial activity was carried out using agar-plate method against various strains of bacteria (Staphylococcus aureus, Bacillus subtillis, Pseudomonas aerugionsa, and Escherichia coli) and spores of fungi (Aspergillus niger and Aspergillus flavous). The results showed significantly higher antimicrobial activity of HQMABS compared to the parent 8-hydroxyquinoline and sulfonamide, while oxinates of HQMABS showed milder activity.

Spectrophotometric estimation of total carotenoids in cereal grain products.

Abstract: Total carotenoids (TC) were determined as a measure of total xanthophylls in grain flours and grits, by new validated spectrophotometric method based on A1cm1%-approach. The general analytical procedure is easily adjustable to different samples, the number of extraction steps depending on TC concentration in the sample. Basically, two methods have been suggested: the rapid one for low-TC samples (white corn, wheat, soybean, sorghum) including one to two extractions, and the one for high-TC samples (yellow corn) needing three to four extractions. Method’s accuracy was proven against the reference standard material (102.1±3.9%) and the reference method. Good precision (repeatability and intermediate precision of upto 9% for yellow corn products)and sensitivity with LOD (limit of detection) and LLOQ (lower limit of quantitation) of 0.2 and 0.6 mg kg–1 TC, resp., were estimated. The method was applied to the control of nutritional value of cereal grain products. TC concentration (in mg kg–1) in the samples ranged from 11–23 in yellow corn flours, 0.7–0.9 in white corn flours, 17–22 in yellow corn grits, 1.1–1.3 in wheat flours, 1.6 in wheat grits and 1.5 in sorghum flour, to 0.9–9.9 in soybean flours.

Velocity of detonation-a mathematical model.

Abstract: Based on the principles of conservation of energy and momentum, a mathematical formula has been derived for the squares of detonation velocities of a large set of explosives. The equation is a function of the total energy and molecular weight of an explosive compound considered. A regressed equation has been obtained for a pool of explosives of various types including nitramines, aliphatic and aromatic nitro compounds. Also another regressed equation for nitramines only is given. For the regression, the total energies are obtained using DFT (UB3LYP/6-31G(d)). The regression statistics are given and discussed.

Room-Temperature Synthesis of 2-Arylbenzothiazoles using Sulfuric Acid Immobilized on Silica as a Reusable Catalyst under Heterogeneous Condition.

Abstract: Application of sulfuric acid immobilized on silica gel as an efficient and benign catalyst has been explored in the synthesis of 2-arylbenzothiazoles via condensation reaction of aldehydes with 2-aminothiophenol. The reactions proceed under heterogeneous and mild conditions in ethanol at room temperature to provide 2-arylbenzothiazoles in high yields.

Cytokinins and their function in developing seeds.

Abstract: Cytokinins are a major group of plant hormones that control various processes in plant growth and development. Chemically they are N 6 -substituated adenine derivatives, including their respective ribotides, ribosides and glucosides. The inter-conversion between different cytokinins metabolites represents the transition between active, inactive, storage and transport forms. This process is in vivo rather dynamic and rapid. We have finally begun to understand the role of cytokinins in plant development through the identification of genes for the first plant enzyme in the biosynthetic pathway, isopentenyl transferases, less than 10 years ago, in addition to research of other enzymes and their corresponding genes that are involved in cytokinin metabolism and signal transduction. This review focuses on the recent findings on cytokinins with an emphasis on their role during the development of seedsfrom which the first natural cytokinin was isolated more that half a century ago.

Electrocatalytic Oxidation of Isoproterenol and its Voltammetric Determination in Pharmaceuticals and Urine Samples Using a Poly(1-methylpyrrole)-DNA Modified Electrode.

Abstract: Determination of isoproterenol (ISP) was carried out using a DNA incorporated poly(1-methylpyrrole) modified glassy carbon electrode (GCE). The poly(1-methylpyrrole)-DNA/GCE showed an excellent electrocatalytic effect on the oxidation of ISP. The poly(1-methypyrrole)-DNA/GCE also accelerated the rate of electron transfer reaction of ISP. Compared with a bare GCE, the poly(1-methylpyrrole)-DNA/GCE exhibits a distinct shift of the oxidation potential of ISP in the cathodic direction and a marked enhancement of the current response. A linear calibration plot was obtained covering the concentration range from 2.0 x 10 -6 to 6.0 x 10- 5 M with a detection limit of 1.60 x 10 -7 M by cyclic voltammetry. The electrode system has also successfully resolved the overlapping anodic peak of ISP and uric acid (UA) into two well-defined voltammetric peaks in cyclic voltammetry at 0.416 V and 0.552 V for ISP and UA, respectively. The poly(1-methypyrrole)-DNA/GCE has successfully been utilised for the determination of ISP in pharmaceutical preparations. The validity of the proposed method was also assured by the recovery of ISP and UA in urine samples.

Apparent molar volumes and viscosity B-coefficients of glycine in aqueous silver sulphate solutions at T = (298.15, 308.15, 318.15) k.

Abstract: Apparent molar volumes (φV) and viscosity B-coefficients for glycine in 0.005, 0.010, 0.015, and 0.020 mol dm-3 aqueous silver sulphate (Ag2SO4) solutions have been determined from solution density and viscosity measurements at (298.15, 308.15, and 318.15) K as a function of glycine concentration. The standard partial molar volume (φV0) and experimental slopes (SV*) obtained from the Masson equation have been interpreted in terms of solute-solvent and solute-solute interactions, respectively. The viscosity data were analyzed using the Jones-Dole equation, and the derived parameters A and B were interpreted in terms of solute-solute and solute-solvent interactions, respectively. The standard volumes of transfer (ΔφV0) and viscosity B-coefficients of transfer (ΔB) of glycine from water to aqueous Ag2SO4 solutions were derived to study various interactions in the ternary solutions. The structure making or breaking ability of glycine has been discussed in terms of the sign of (δ2φV0/δT2)P. The activation parameters of viscous flow for the ternary solutions were also calculated and explained in terms of transition state theory.

Bleaching Kinetic and Mechanism Study of Congo Red Catalyzed by ZrO2 Nanoparticles Prepared by Using a Simple Precipitation Method.

Abstract: Bleaching of Congo red catalyzed by ZrO 2 nanoparticles was study under UV and sunlight irradiations. The nanoparticles of ZrO 2 have been synthesized by controlled precipitation method. The concentration of ZrOCl 2 and ammonia reactants and the calcinations temperature of ZrO 2 were optimized for the control of nanoparticles size. Characterization of the prepared nanoparticles was studied by using XRD patterns, TEM images and FT-IR spectra. The tetragonal phase of zirconium oxide was obtained at 550 °C and show the most catalytic effect in dye degradation. The various parameters such as the irradiation time, amount of nanophotocatalyst, pH of samples, and initial concentration of Congo red were studied to find desired conditions of photodegradation process. The degradation 98% was achieved at pH 7 catalyzed by 0.7 g/L if ZrO 2 nanoparticles in duration time of 125 min. The effect of iso-PrOH, hydrogen peroxide and inorganic anions was studied on the degradation efficiency of dye. The degradation 98% was obtained in the presence of prepared nanosized zirconia in comparison with degradation 65% catalyzed by commercially zirconia.

Omega polynomial revisited.

Abstract: Omega polynomial was proposed by Diudea (Omega Polynomial, Carpath. J. Math., 2006, 22, 43-47) to count the opposite topologically parallel edges in graphs, particularly to describe the polyhedral nanostructures. In this paper, the main definitions are re-analyzed and clear relations with other three related polynomials are established. These relations are supported by close formulas and appropriate examples.

Distribution of Microamounts of Cesium in the Two-Phase Water-HCl-Nitrobenzene-2,3-Naphtho-15-crown-5-Hydrogen Dicarbollylcobaltate Extraction System.

Abstract: Extraction of microamounts of cesium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H + B ― ) in the presence of 2,3-naphtho-15-crown-5 (N15C5, L) has been investigated. The equilibrium data have been explained assuming that the complexes HL + , HL + 2 , CsL + and CsL + 2 are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.

Metallic fluoride complexes as phosphate analogues for structural and mechanistic studies of phosphoryl group transfer enzymes.

Abstract: There have been intensive efforts to try to understand the details of phosphoryl transfer reactions extending from non-enzymatic (or enzyme model) systems to the mechanisms of the enzyme catalysed reactions. As phosphate analogues, few metallic fluorides AlF x , BeF x and MgF x affect the activity of a variety of phosphoryl transfer enzymes, and it is accepted that these small inorganic complexes are useful chemical probes for structural and mechanistic studies in enzymology because they are able to mimic phosphoryl group in ground state (BeF x ) as well as in transition state (AlF x ,Mg-F x ). Al 3+ and Be 2+ tend to form stable complexes with different fluoride anions (x = 1 to 4) spontaneously in aqueous solution but Mg 2+ does not. BeF x geometry is strictly tetrahedral resembling the phosphate ground state when bound to an acyl group of protein active site (phosphorylated acyl groups are unstable otherwise), or the Michaelis complex when BeF x concominantly with nucleoside diphosphate replaces γ-phosphate group in nucleoside triphosphate sites. AlF x and MgF x are identified as enzymatic analogues of phosphoryl transition state where both are able to form different coordination geometries within the enzyme active sites: trigonal bipyramidal (AlF 3 and MgF 3 ― ) or octahedral (AlF 4 ― or Mg-F 4 2― ). The geometry and charge of MgF 3 ― are the best suited to mimicking the trigonal planar PO 3 ― moiety of phosphoryl transfer transition state but MgF 3 ― does not, unlike aluminum and beryllium fluoride complexes, exists in solution and can be assembled and stabilized in suitable active site only. Therefore it is particularly interesting to characterize as a potentially highly accurate transition state analogue and may be the best reagent of choice for studying phosphoryl transfer reactions in future.

Immobilization of yeast cells within microchannels of different materials.

Abstract: Saccharomyces cerevisiae was successfully immobilized on the inner wall surface of channels of submillimeter diameter, which can be further used for the development of a highly productive continuous biotransformation process within a microfluidic device. Covalent bonding by means of 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde was used for immobilization of cells to microchannels made of glass, polystyrene (PS), polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP). All tested materials were successfully functionalized with H2SO4 to promote silanization. The effect of reaction time with acid on immobilization efficiency was studied for polymer materials. This is the first report on cell immobilization onto PTFE, FEP and PFA surface, which enables to develop a microfluidic device with surface bound biocatalyst from low cost and disposable materials.

Biosorption of Cadmium, Cobalt and Zinc by Moss Rhytidiadelphus squarrosus in the Single and Binary Component Systems.

Abstract: Biomass of moss Rhytidiadelphus squarrosus was studied as a potential biosorbent for cadmium, cobalt and zinc removal from single and binary solutions. It was shown that solution pH significantly influenced Cd, Co and Zn biosorption. Maximum uptake was reached at pH 5.0-6.0 and negligible biosorption was observed at pH 2.0. Experimental equilibrium biosorption data for cadmium, cobalt and zinc were analysed by the Langmuir and Freundlich isotherm models. The Langmuir isotherm was found to well represent the measured sorption data in single metal systems. The maximum sorption capacities Qmax onto moss biomass were 186 µmol/g for Zn, 173 µmol/g for Cd and 123 µmol/g for Co. Results revealed that the presence of Cd more significantly decreased the sorption of Co in binary Cd-Co mixtures than vice versa. In Cd-Zn binary system, both cadmium and zinc were sorbed with equal efficiency. The competitive Langmuir equations were used to fit the experimental data from the Zn-Cd and Cd-Co binary systems and simple two-dimensional isotherm curves were replaced by three-dimensional sorption isotherm surfaces.

Extraction of Calcium and Strontium into Phenyltrifluoromethyl Sulfone by Using Synergistic Mixture of Hydrogen Dicarbollylcobaltate and "Classical" CMPO.

Abstract: Solvent extraction of microamounts of calcium and strontium by a phenyltrifluoromethyl sulfone (FS 13) solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of octyl-phenyl-N,N-diisobutylcarbamoylmethyl phosphine oxide ("classical" CMPO, L) has been investigated. The equilibrium data have been explained assuming that the species HL+, HL2+, ML2+, ML2+2 and ML2+3 (M2+ = Ca2+, Sr2+) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species in FS 13 saturated with water have been determined. In the considered FS 13 medium, it was found that the stability constants of the complex species CaL2+n, where n = 1, 2, 3 and L is "classical" CMPO, are higher than those of the corresponding complexes SrL2+n.

Ranking of QSAR Models to Predict Minimal Inhibitory Concentrations Toward Mycobacterium tuberculosis for a Set of Fluoroquinolones.

Abstract: CP-ANN technique was used to build 54 different QSAR models. The models were built for three sets (assays) of fluoroquinolones considering their antituberculosis activity and using different technical parameters (dimension of network and number of learning epochs). The models served as a reliable basis for ranking by a new powerful method based on sum of ranking differences (SRD). With the applied SRD procedure we can find the optimal ones. The best model can be selected easily for the first assay. Two models can be recommended for the second assay, and no recommended model was found for the assay3.

Potential of Phenolic Antioxidants

Abstract: In vitro studies have shown a link between the consumption of food rich in (poly)phenols, especially flavonoids, and reduced risk of coronary heart diseases. Several flavonoids have been reported to prevent low density lipoprotein cholesterol oxidation in vitro. The aim of our work was to determine antioxidant and radical scavenging activity of flavonoids myricetin, quercetin, rutin, luteolin, apigenin, kaempferol, catechin, epicatechin and epigallocatechin gallate and to study the influence of chemical structure and flavonoid interactions on the ability to inhibit oxidation and scavenge free radicals. Two in vitro methods, i.e. oxidation of b-carotene in an emulsion system and DPPH (1,1-Diphenyl-2-picrylhydrazyl) radical scavenging assay, were applied. In addition, a review of in vivo studies that investigate the effectiveness of food flavonoids in reducing oxidative damage in human body was done and their results were analyzed and compared to in vitro results obtained in our laboratory. Although all tested flavonoids except apigenin showed strong antioxidant and antiradical properties in vitro, these findings can not be completely confirmed from the reviewed in vivo human studies since those results are sometimes contradictory and inconsistent.

Synthesis and Characterization of Two Diimine Schiff Bases Derived from 2,4-Dimethoxybenzaldehyde: The Crystal Structure of N,N'-Bis(2,4-dimethoxy- benzylidene)-1,2-diaminoethane

Abstract: Two diimine Schiff bases derived from 2,4-dimethoxybenzaldehyde; N,N'-bis(2,4-dimethoxybenzylidene)-1,2-diaminoethane (1) and N,N'-bis(2,4-dimethoxybenzylidene)-1,4-diaminobutane (2), were prepared and characterized by elemental analyses, FT-IR and 1 H NMR spectroscopy. The crystal structure of 1 has been determined by single crystal X-ray diffraction. Its molecule adopts an E configuration with respect to the C=N bond and is located on a center of inversion with one half-molecule in the asymmetric unit.

Using Different Experimental Designs in Drug-Excipient Compatibility Studies During the Preformulation Development of a Stable Solid Dosage Formulation

Abstract: Different types of factorial experimental designs can be used in compatibility studies of drug development, where many different factors and their interactions should be evaluated to predict their effects on the degradation of the drug substance under study. All possible main and interaction effects of different potential excipients that can constitute the drug product should be evaluated in order to select the best combination of excipients that give the lowest possible degradation, i.e., the most stable drug product. Statistical experimental designs enable the user to obtain the maximum amount of information, i.e., the degradation effects of excipients and their interactions on the stability of the drug substance, on the basis of the smallest possible number of experiments. The use of full and two different fractional factorial designs is described using a real example where the excipients that stabilize the drug substance or cause as little degradation as possible are selected for a solid dosage formulation. It was shown that the type and the sequence of design used during the studies are also important to get reliable and valuable results. A thorough explanation of the statistical evaluation of data and different presentations of final solutions are given.

Amberlite XAD-4 Impregnated With a New Pentadentate Schiff base: a Chelating Collector for Separation and Preconcentration of Trace Amounts of Gallium (III) and Indium (III).

Abstract: A new solid-phase extraction method for separation and preconcentration of trace amounts of Ga(III) and In(III) in biological and water samples is proposed. The procedure is based on the adsorption of Ga(III) and In(III) ions on a column of Amberlite XAD-4 resin loaded with newly-synthesized pentadentate naphthol-derivative Schiff base 1-{[(6-{[(E)-1(2-hydroxy-1-naphthyl)methylidene]amino}-2-pyridyl)imino]methyl}-2-naphthol (HMPN) prior to their determination by flame atomic absorption spectrometry (FAAS). The optimum pH values for quantitative sorption of Ga(III) and In(III) are 4.5–6.0 and 4.5–8.0, respectively, and their desorptions can be achieved by using 5 mL of 0.5 M HNO3. The sorption capacities of the resin for Ga(III) and In(III) were 1.27 and 1.45 mg g –1 , respectively. The enrichment factor for preconcentration of Ga(III) and In(III) was found to be 200. The precision of the method, evaluated as the relative standard deviation obtained by analyzing a series of ten replicates, was below 3% for both elements. The proposed procedure was applied to the analysis of synthetic seawater, natural waters, wastewater and human blood serum using flame AAS.