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Articles 2371 - 2400 of 2720
Full-Text Articles in Chemistry
Phenylethanoid Glycosides From Scutellaria Galericulata, Tayfun Ersöz, Deni̇z Taşdemi̇r, İhsan Çaliş, Chris M. Ireland
Phenylethanoid Glycosides From Scutellaria Galericulata, Tayfun Ersöz, Deni̇z Taşdemi̇r, İhsan Çaliş, Chris M. Ireland
Turkish Journal of Chemistry
From the aerial parts of Scutellaria galericulata L., four phenylethanoid glycosides, 2-(4-hydroxyphenyl)-ethyl-(6-O-caffeoyl)-\beta -D-glucopyranoside (1), calceolarioside B (2), osmanthuside E (3) and martynoside (4), were isolated. The structure elucidations of the isolated compounds were performed by spectroscopic (UV, IR, ESI-MS, 1D- and 2D-NMR) methods. Compounds 1-4 demonstrated scavenging properties toward the 1,1-diphenyl-1-picrylhydrazyl (DPPH) radical in TLC autographic assays.
Solid-Phase Extraction Of Copper With Lead 4-Benzylpiperidinedithiocarbamate On Microcrystalline Naphthalene And Its Spectrophotometric Determination, Hasan Cesur, Beki̇r Bati
Solid-Phase Extraction Of Copper With Lead 4-Benzylpiperidinedithiocarbamate On Microcrystalline Naphthalene And Its Spectrophotometric Determination, Hasan Cesur, Beki̇r Bati
Turkish Journal of Chemistry
Using lead 4-benzylpiperidinedithiocarbamate complex (Pb(4-BPDC)_{2}), a solid-phase extraction method was developed for pre-concentration and spectrophotometric determination of copper in water samples. In this method, copper in large volume liquid phase quantitatively replaces lead on colorless Pb(4-BPDC)_{2} complex and naphthalene solid phase mixture forming Cu-4-benzylpiperidinedithiocarbamate complex (Cu(4-BPDC)_{2}). The solid phase containing colored Cu(4-BPDC)_{2} is dissolved in chloroform and its absorbance is measured at 437 nm against the reagent blank. The range of linearity is 0.4 -10 \mu gml^{-1} of copper in chloroform, the molar absorptivity of the complex determined from the linear portion of Beer's law plot is 8.197x10^{3} lmol^{-1}cm^{-1} and …
Electrochemical Behavior Of Benzo[C]Cinnoline And Its Bromo Derivatives, Ni̇lgün Seçken, M. Levent Aksu, Ali̇ Osman Solak, Emi̇ne Kiliç
Electrochemical Behavior Of Benzo[C]Cinnoline And Its Bromo Derivatives, Ni̇lgün Seçken, M. Levent Aksu, Ali̇ Osman Solak, Emi̇ne Kiliç
Turkish Journal of Chemistry
The electrochemical behavior of benzo[c]cinnoline and some of its bromo derivatives was studied. Two discrete 2-electron reduction waves in acidic and only one wave in basic media in ethyl alcohol-BR buffer system (l:5 v/v) were observed. A mechanism for the electrode reaction is proposed. Diffusion coefficients, formal potentials for and the derivatives, the number of electrons transferred were determined by using sampled current polarography, cyclic voltammetry, chronoamperometry, chronocoulometry and constant potential coulometry. Adsorption of the molecules on the surface of the mercury drop was analyzed and this phenomena was exploited to calculate the formal potentials and the diffusion coefficients of …
Determination Of Linear Alkylbenzene Sulphonates And Their Biodegradation Intermediates By Isocratic Rp-Hplc, Mehmet Akyüz, David J. Roberts
Determination Of Linear Alkylbenzene Sulphonates And Their Biodegradation Intermediates By Isocratic Rp-Hplc, Mehmet Akyüz, David J. Roberts
Turkish Journal of Chemistry
An HPLC method was developed to determine linear alkylbenzene sulphonates (LASs) and their biotransformation products sulphophenyl carboxylates by isocratic chromatography using two C_{18} columns in series. Solid-phase extraction with a (C_{18}) cartridge was employed to isolate LAS from sediment and sewage effluent samples. Sodium perchlorate and ammonium perchlorate were used as ion pair agents. The recovery of the compounds was 94% \pm 2 and 98% \pm 2 respectively for sediment and sewage effluent. It was demonstrated that it is possible to separate LAS compounds and their isomers and homologues using this system.
Determination Of Fatty Acid Composition And Total Trans Fatty Acids In Cereal-Based Turkish Foods, Orhan Dağlioğlu, Murat Taşan, Bariş Tunçel
Determination Of Fatty Acid Composition And Total Trans Fatty Acids In Cereal-Based Turkish Foods, Orhan Dağlioğlu, Murat Taşan, Bariş Tunçel
Turkish Journal of Chemistry
The fatty acid composition and trans fatty acids of 13 cereal-based foods produced by Turkish companies were analysed by capillary gas-liquid chromatography. The total fat contents of the samples ranged from 1.8 to 37.9%. Traditional Turkish white bread and bulgur had the lowest fat content (1.8% and 2.3% respectively) and wafer the highest (37.9%). The major fatty acids in the samples were C_{16:0}, C_{18:0}, trans C_{18:1}, C_{18:1} and C_{18:2}. Total unsaturated fatty acid contents varied between 49.0 and 80.3% of total fatty acids, and bulgur had the highest percentage among the samples. Except for bulgur, all the samples contained trans …
Synthesis Of 1,4-Diazepine Nucleosides, M. Zia-Ul-Haq, Shahid Hameed, Helmut Duddeck, Roshan Ahmed
Synthesis Of 1,4-Diazepine Nucleosides, M. Zia-Ul-Haq, Shahid Hameed, Helmut Duddeck, Roshan Ahmed
Turkish Journal of Chemistry
The phenolic \beta-diketones I prepared by modified Baker-Venkataraman rearrangement were converted to the flavones II in acidic medium which on treatment with aqueous ethylenediamine/propylenediamine gave diazepine derivatives III. After coupling with acetobromo sugars in the presence of mercuric cyanide and nitromethane, deacetylation in methanolic ammonia yielded nucleosides V. The structures of all the intermediates and final products were confirmed with the help of modern spectroscopic techniques.
Acid-Base Equilibria Of Some N-Substituted Thiophene-2-Carboxamidoximes In Non-Aqueous Media, Nedi̇me Dürüst, Yaşar Dürüst, İlknur Meri̇ç
Acid-Base Equilibria Of Some N-Substituted Thiophene-2-Carboxamidoximes In Non-Aqueous Media, Nedi̇me Dürüst, Yaşar Dürüst, İlknur Meri̇ç
Turkish Journal of Chemistry
The protonation constants of the amino nitrogens of some N-substituted thiophene-2-carboxamidoximes have been determined in acetic acid by means of potentiometric titration with perchloric acid. pK_{a} values of the title compounds were interpreted on the basis of structural effects due to the substituents and the main skeleton.
The Selective Protection And Deprotection Of Ambident Nucleophiles With Parent And Substituted Triarylmethyls, İbrahi̇m Demi̇rtaş, Bülent Büyükkidan, Mahfuz Elmastaş
The Selective Protection And Deprotection Of Ambident Nucleophiles With Parent And Substituted Triarylmethyls, İbrahi̇m Demi̇rtaş, Bülent Büyükkidan, Mahfuz Elmastaş
Turkish Journal of Chemistry
N-triphenylmethyl and N-4,4'-dimethoxytriphenylmethyl of o-aminophenol, m-aminophenol, and p-aminophenol compounds were easily prepared from triphenylmethyl chloride and 4,4'-dimethoxytriphenyl- methyl chloride. S-triphenylmethyl-2-mercapto ethanol was also selectively synthesized using the triphenylmethyl chloride and 2-mercapto ethanol. The reactivity of nitrogen and sulfur versus oxygen in the protection reactions was compared. In principle, the protection of aminophenols and 2-mercapto ethanol with triarylmethyls (trityls) may take place on the oxygen. However, in this framework, we discuss the different reactivities of oxygen, nitrogen and sulfur towards triphenylmethyl chloride (TrCl) and 4,4'-dimethoxytriphenylmethyl chloride (DMTrCl) and find that nitrogen and sulfur are more reactive than oxygen.
New Triterpenic Saponins From Cephalaria Transsylvanica, Süheyla Kirmizigül, Hüseyi̇n Anil
New Triterpenic Saponins From Cephalaria Transsylvanica, Süheyla Kirmizigül, Hüseyi̇n Anil
Turkish Journal of Chemistry
Three new triterpenic saponins, 3-O-[\beta-D-xylopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin 28-O-[\beta-D-glucopy\-ranosyl (1 \to 4)-\beta-D-glucopyranosyl] ester (1), 3-O-[\beta-D-glucopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin 28-O-[\beta -D-glucopyranosyl] ester (2) and 3-O-[\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin(3) were isolated from Cephalaria transsylvanica. After cleavage of the ester-glycosidic linkage of the bisdesmosidic compounds, two new prosapogenins, 3-O-[\beta-D-xylopyranosyl (1 \to 4)-\beta-D-glucpyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin (4) and 3-O-[\beta-D-glucopyranosyl (1 \to 4)- \beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin (5) were also isolated. The structures …
Pyridine And Benzene Templated Potential Peptidomimetics, Kadi̇r Dabak
Pyridine And Benzene Templated Potential Peptidomimetics, Kadi̇r Dabak
Turkish Journal of Chemistry
This study provides a new approach for the synthesis of pyridine and benzene templated potential peptidomimetics. By the attachment of various amino acid side chains in different combinations on the pyridine template at the 2- and 3- positions and on the benzene core at 1,2,4 positions, different peptidomimetics may be obtained. Arg-10, Leu-11 and Tyr-13 amino acid side chain mimics and their precursors were attached to the pyridine and benzene core with a special arrangement to produce potential peptidomimetics of omega-conotoxin MVIIA.
Metallation Of Mesitylene By Organolithium Compounds In The Presence Of Lithium Polyether Alkoxides, Tuba Kayhan, Ni̇han Nugay, Turgut Nugay
Metallation Of Mesitylene By Organolithium Compounds In The Presence Of Lithium Polyether Alkoxides, Tuba Kayhan, Ni̇han Nugay, Turgut Nugay
Turkish Journal of Chemistry
The catalytic effect of polyether alkoxides (PEAs) on the activity Of organolithium compounds as a metallating agent studied. The sites of metallation as mono, di, tri, and gem metallation at three different benzylic positions were investigated in terms of relative yield by using gas chromatography-mass spectroscopy (GC-MS couple) techniques. The yield of the trimetallated (1,3,5-metallated) mesitylene was optimized by improving the metallation conditions. Special attention was paid to the effect of metal type, alkoxide structure, solvent polarity, temperature and also relative mole ratios of was reactants such as alkoxide to mesitylene and n-butyllithium to mesitylene on metallation reactions. It was …
Kinetic Spectrophotometric Determination Of Nanogram Levels Of Manganese (Ii) By Azo Dye -- Potassium Periodate -- 1,10-Phenanthroline System, Konstantin L. Mutaftchiev
Kinetic Spectrophotometric Determination Of Nanogram Levels Of Manganese (Ii) By Azo Dye -- Potassium Periodate -- 1,10-Phenanthroline System, Konstantin L. Mutaftchiev
Turkish Journal of Chemistry
The catalytic effect of manganese (II) on the oxidation of 3 - Methyl - 6 - (2 - hydroxyethoxy) - 2 - [2 - methoxy - 4 - N (N,N - diethylamino) phenylazo] benzothiazolium methylsulphate (MHMDPBM), with potassium periodate in the presence of 1,10-phenanthroline in weakly acidic media was studied. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of the dye at 560 nm. Under the optimum conditions (4x10^{- 5} mol dm^{- 3} MHMDPBM, 4x10^{- 4} mol dm^{- 3} potassium periodate, 1x10^{- 4} mol dm^{- 3} 1,10-phenanthroline, 0.1 mol dm^{- 3} buffer -- pH 3.0, 70^oC, …
Automated Recognition Of Ergogenic Aids Using Soft Independent Modeling Of Class Analogy (Simca), M. Praisler, J. Van Bocxlaer, A. De Leenheer, D. L. Massart
Automated Recognition Of Ergogenic Aids Using Soft Independent Modeling Of Class Analogy (Simca), M. Praisler, J. Van Bocxlaer, A. De Leenheer, D. L. Massart
Turkish Journal of Chemistry
The introduction of effective drug testing procedures in doping control reduced, but did not eliminate, their abuse by athletes. The most important analytical challenge is the recognition of the new analog compounds. In attempts to circumvent existing controlled substance laws, slightly modified chemical structures (by adding or changing substituents at various positions on the banned molecules) are used. As a result, no substance belonging to a prohibited class may be used nowadays, even if it has not been specifically listed. We present a chemometric procedure acting as an automated GC-FTIR screening test detecting the molecular structural similarity of unknown compounds …
Partially Purification And Characterization Of Polyphenol Oxidase Of Quince, Hülya Yağar, Ayten Sağiroğlu
Partially Purification And Characterization Of Polyphenol Oxidase Of Quince, Hülya Yağar, Ayten Sağiroğlu
Turkish Journal of Chemistry
Polyphenol oxidase (PPO, EC 1.14.18.1) was extracted from quince (Cydonia oblonga) by using 0.1 M phosphate buffer, pH 6.8. The polyphenol oxidase of quince was partially purified by (NH_{4})_{2}SO_{4} and dialysis. Substrate specificity experiments were carried out with catechol, pyrogallol, L-DOPA, p-cresole and tyrosine. Catechol was the most suitable substrate compound for quince PPO. The Michaelis constants were 4.54 mM, 7.35mM and 17.8 mM for catechol, pyrogallol and L-DOPA, respectively at 25^oC. The optimum pH and temperature were determined with the specific substrate catechol as 8.0 and 40$^oC, respectively. Of eight inhibitors tested L-cysteine, ascorbic acid and potassium cyanide were …
Vibrational Spectra And Assignments Of Cis- And Trans-1,4-Polybutadiene, P. Nallasamy, P.M. Anbarasan, S. Mohan
Vibrational Spectra And Assignments Of Cis- And Trans-1,4-Polybutadiene, P. Nallasamy, P.M. Anbarasan, S. Mohan
Turkish Journal of Chemistry
The Raman spectra of cis- and trans-1,4- polybutadiene were recorded in the region 100-4000 cm^{-1} and its infrared spectra were also measured in the wave number range 200--4000 cm^{-1}. The spectra were completely analysed. Probable assignments to observed bands were made with the help of intensities and normal co-ordinate analysis. The calculated normal frequencies were in good agreement with the experimental ones.
Iridoid And Phenylpropanoid Glycosides From Phlomis Grandiflora Var. Fimbrilligera And Phlomis Fruticosa, Tayfun Ersöz, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Ali̇ Arslan Dönmez
Iridoid And Phenylpropanoid Glycosides From Phlomis Grandiflora Var. Fimbrilligera And Phlomis Fruticosa, Tayfun Ersöz, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Ali̇ Arslan Dönmez
Turkish Journal of Chemistry
From the aerial parts of Phlomis grandiflora var. fimbrilligera, two iridoid glucosides, 8-epi-loganin (1) and auroside (2), together with five phenylethanoid glycosides, forsythoside B (3), alyssonoside (4), verbascoside (5), hattushoside (6) and phlomisethanoside (7), were isolated. Iridoid glucosides auroside (2) and lamiide (8) and phenylethanoid glycosides, forsythoside B (3), alyssonoside (4), and verbascoside (5) as well as a lignan glucoside, syringaresinol-4 ' -O-\beta -D-glucoside (9), were characterized from the overground parts of P. fruticosa. The structures of the isolates were elucidated by means of one and two dimensional (COSY, HSQC and HMBC) NMR techniques and ESI MS.
Investigation Of The Microporous And Mesoporous Structures Of The Reşadiye (Tokat/Turkey) Bentonite And Its Fractions, Müşerref Önal, Yüksel Sarikaya, Tülay Alemdaroğlu
Investigation Of The Microporous And Mesoporous Structures Of The Reşadiye (Tokat/Turkey) Bentonite And Its Fractions, Müşerref Önal, Yüksel Sarikaya, Tülay Alemdaroğlu
Turkish Journal of Chemistry
It was determined by X-ray diffraction that, besides containing clay minerals such as montmorillonite and illite, the original bentonite contained also clinoptilolite, opal-C, quartz, calcite and dolomite. The original bentonite was separated into four fractions by decantation and precipitation from its aqueous suspension. The adsorption and desorption of nitrogen on the original bentonite and its fractions at 77 K were investigated. The specific surface areas of the samples were determined according to the methods of Brunauer-Emmett-Teller, de Boer-Lippens, and Harkins-Jura by using the adsorption data. The mesopore size distribution curves were plotted by using the desorption data. The specific micropore …
Investigations On The Electrochemical Surface Treatment Of Carbon Fibers, Erdal Bayramli, Levent Toppare, Naci̇ Kutay Eri̇nç
Investigations On The Electrochemical Surface Treatment Of Carbon Fibers, Erdal Bayramli, Levent Toppare, Naci̇ Kutay Eri̇nç
Turkish Journal of Chemistry
Desized polyacrylonitrile (PAN) based carbon fibers (CF) were chemically and electrochemically oxidized and reduced. CF surfaces were activated via cyclic voltammetry studies with anodic and cathodic scans. The changes in CF surfaces were studied by contact angle measurements. Lifshitz-van der Waals and acid-base components of single fibers were determined. In general, oxidation resulted in the formation of an acidic surface energy component and reduction gave rise to no change in the number of basic functionalities at the CF surface.
Oxidation Of Ethylenediaminetetraacetic Acid By N-Bromosuccinimide In Aqueous Alkaline Medium -- A Kinetic Study, S. K. Mavalangi, M. R. Kembhavi, S. T. Nandibewoor
Oxidation Of Ethylenediaminetetraacetic Acid By N-Bromosuccinimide In Aqueous Alkaline Medium -- A Kinetic Study, S. K. Mavalangi, M. R. Kembhavi, S. T. Nandibewoor
Turkish Journal of Chemistry
The kinetics of oxidation of ethylenediaminetetraacetic acid (EDTA) by N-bromosuccinimide (NBS) in aqueous alkaline media was investigated at 25°C. Analysis of the results showed the reaction is first -- order with respect to [NBS] and apparently less than unit order each with respect to [EDTA] and [alkali]. The influence of the reaction products, ionic strength, temperature effect and dielectric constant of the medium on the rate of reaction was studied. The proposed mechanism is consistent with the observed kinetics. The reaction constants involved in the mechanism were derived. There is a good agreement between the observed and calculated rate constants …
Separation Process Of Citric Acid With Tertiary Amines/Diluents In Supercritical Co_{2}, Arzu Koparan, Afi̇fe Güvenç, Nurcan Kapucu, Ülkü Mehmetoğlu, Ayla Çalimli
Separation Process Of Citric Acid With Tertiary Amines/Diluents In Supercritical Co_{2}, Arzu Koparan, Afi̇fe Güvenç, Nurcan Kapucu, Ülkü Mehmetoğlu, Ayla Çalimli
Turkish Journal of Chemistry
Reactive extraction of citric acid was investigated at atmospheric and supercritical conditions. The most suitable diluent and amine from among the tertiary amines and eight different diluents were determined at atmospheric conditions. The distribution coefficient values obtained with Hostarex A 327 were higher than those of Alamine 336. The selected amine (Hostarex A327) and the diluent (Oleyl alcohol) were used for reactive extraction of citric acid at supercritical conditions. Separation yields of citric acid were obtained in the temperature ranges of 308 to 328 K and in the pressure ranges of 80 to 180 bars in a supercritical extraction system …
Electrorheological Properties Of Suspensions Prepared From Polystyrene- Block- Polyisoprene Copolymer, Hali̇l İbrahi̇m Ünal, Yilmaz Yildirir, Mustafa Yavuz
Electrorheological Properties Of Suspensions Prepared From Polystyrene- Block- Polyisoprene Copolymer, Hali̇l İbrahi̇m Ünal, Yilmaz Yildirir, Mustafa Yavuz
Turkish Journal of Chemistry
Considerable scientific and industrial interest is currently being focused on a class of materials known as electrorheological (ER) fluids, which display remarkable rheological behaviour, being able to convert rapidly and repeatedly from a liquid to solid when an electric field (E) is applied or removed. In this article, the synthesis, characterization, partial hydrolysis and ER properties of polystyrene- block}-polyisoprene copolymer (COP) were investigated. The block copolymer was characterized by GPC, viscosity measurements, ^1 H-NMR and FTIR spectroscopies, particle size measurements, and elemental analysis. The polystyrene block of the copolymer was partially hydrolyzed by a series of chemical reactions and then …
Determination Of Hydrochlorothiazide And Enalapril Maleate In Tablet Formulations By Reversed-Phase Hplc, Idrees F. Al-Momani̇
Determination Of Hydrochlorothiazide And Enalapril Maleate In Tablet Formulations By Reversed-Phase Hplc, Idrees F. Al-Momani̇
Turkish Journal of Chemistry
A high-performance liquid chromatographic procedure is presented for the determination of hydrochlorothiazide (HCT) and enalapril maleate (EM) in pharmaceutical tablets. An aliquot of the sample is dissolved in 15% acetonitrile (ACN) containing thiophylline as an internal standard and chromatographed on a Supelcosil LC-8 (5 \mu m), (150 mm x 4.6 mm i.d.) column. The mobile phase was 3.0 mM tetrabutylammoniumhydrogen sulfate (TBAHS) in ACN/water/triethylamine (TEA), (14, 85.6, 6.4 V/V) adjusted to pH 4.1 by glacial acetic acid. The detection was at 220 nm. The method was tested for linearity, accuracy, recovery, and specificity.
A Comparative Study On The Recovery Of Ecori Endonuclease From Two Different Genetically Modified Strains Of Escherichia Coli, Candan Tamerler, Zeynep İlsen Önsan, Betül Kirdar
A Comparative Study On The Recovery Of Ecori Endonuclease From Two Different Genetically Modified Strains Of Escherichia Coli, Candan Tamerler, Zeynep İlsen Önsan, Betül Kirdar
Turkish Journal of Chemistry
A laboratory scale procedure developed for the purification of EcoRI restriction endonuclease was applied to two different Escherichia coli} strains, E. coli 294 and E. coli M5248, which are genetically modified to overproduce the enzyme. The purification method consisted of three successive chromatographic steps including phosphocellulose and hydroxyapatite columns and further fractionation in a second phosphocellulose column. It was shown that the second phosphocellulose separation can be omitted in the case of E. coli 294. Quality control tests indicated enzyme preparations free of contaminants and endo- or exo-nucleases. The yields obtained at the final stage of the purification were 1.3x10^{5} …
Fluorimetric Detection Of Insulin In The Presence Of Eu(Iii) - {Pyridine - 2,6 - Dicarboxylate} Tris Complex, Elmas Gök, Serdar Ateş
Fluorimetric Detection Of Insulin In The Presence Of Eu(Iii) - {Pyridine - 2,6 - Dicarboxylate} Tris Complex, Elmas Gök, Serdar Ateş
Turkish Journal of Chemistry
Bovine insulin solutions (pH=9.3) have maximum absorption at 278 \pm 2 nm and an intrinsic emission at 305 nm when excited at 282 nm. The relative fluorescence intensities show linear dependence on its concentration: 10 \mug/mL< [Ins] < 200 \mug/mL. When Eu(PDA)_{3}^{3-} tris complex is added to these solutions, it has a hyperchromic effect at 278 nm absorption band of insulin, sensitizing the emission intensities of central Eu^{3+} metal ion of the complex at 590 and 615 nm, and simultaneously quenching the emission intensity of hormone at 305 nm. Stern-Volmer plots show that a mechanism of bimolecular quenching at 305 nm and sensitization at 615 nm are valid up to a mole ratio, R = [Eu(PDA)_{3}^{3-}]/[Ins] < 2.0. An intramolecular rather than an intermolecular energy transfer is proposed. An apparent binding constant, log K_{app}=4.70 \pm 0.13, is calculated for Ins-[Eu(PDA)_{3}^{3-}]_{2} type product, the presence of which may offer a new luminescence technique as a diagnostic tool and an alternative to radio-iodinated (^{131}I -) insulin. A simple, rapid and accurate quantitation of insulin is proposed by using a fixed concentration of Eu(PDA)_{3}^{3-}, and measuring its initial F_{0} at \lambda_{exc}/ \lambda_{em}=282/615 nm and the difference, \DeltaF after sensitization when \sim 100 microliters of insulin sample is added. The coefficient of variation (CV), the relative error and minimum detectable amount of bovine insulin hormone are found to be 3.0%, 1.2% and 7.3 \pm 0.2 \mug /mL respectively.
The Isolation Of Carboxylic Acids From The Flowers Of Delphinium Formosum, Nedi̇me Dürüst, Seçki̇n Özden, Esra Umur, Yaşar Dürüst, Mustafa Küçüki̇slamoğlu
The Isolation Of Carboxylic Acids From The Flowers Of Delphinium Formosum, Nedi̇me Dürüst, Seçki̇n Özden, Esra Umur, Yaşar Dürüst, Mustafa Küçüki̇slamoğlu
Turkish Journal of Chemistry
From the flowers of Delphinium formosum Boiss. et Huet. (Ranunculaceae) trans-aconitic, p-hydroxybenzoic, p-coumaric, caffeic and chlorogenic acids were isolated and identified. In addition, protocatechuic, vanillic and gentisic acids were identified.
Determination Of Fluoride And Some Metal Ion Levels In The Drinking Waters In Kayseri Province, Şeri̇fe Tokalioğlu, Uğur Şahi̇n, Şenol Kartal
Determination Of Fluoride And Some Metal Ion Levels In The Drinking Waters In Kayseri Province, Şeri̇fe Tokalioğlu, Uğur Şahi̇n, Şenol Kartal
Turkish Journal of Chemistry
Fluorine is one of the most common elements in the Earth's crust. Fluoride is recognized to be the most effective caries-preventive agent. The main sources of fluoride for people are generally food and drinking water. For this reason, the fluoride and also the metal ion (Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn) concentrations in the drinking waters collected from the city center of Kayseri and its counties were investigated. In the determination of fluoride and of Na and K, an ion-meter with a combination-fluoride electrode and a flame photometer were used, respectively. The levels of …
Cross-Correlation Noise Studies In Atomic Magnet-Optic Rotation Spectroscopy, Ahmet T. İnce
Cross-Correlation Noise Studies In Atomic Magnet-Optic Rotation Spectroscopy, Ahmet T. İnce
Turkish Journal of Chemistry
Analytical signals in an Atomic Magneto-Optic Rotation spectrometer are buried in noise at the limit of detection. The noisy analytical signals were analysed by carrying out mathematical correlation of their time domain waveforms. The noise components of signals were removed by auto-correlation to simplify the study. If noise interferes in analytical signals whose source is unclear, a cross-correlation of the output waveform with noise source may identify the source, e.g., mains frequencies and background radio signals. A cross-correlation will reveal whether the two signals are derived from the same source. This can also lead to an improvement in the signal …
Simultaneous Determination Of Inorganic Anions And Organic Acids By Capillary Electrophoresis, Nevi̇n Özteki̇n, F. Bedi̇a Eri̇m Berker
Simultaneous Determination Of Inorganic Anions And Organic Acids By Capillary Electrophoresis, Nevi̇n Özteki̇n, F. Bedi̇a Eri̇m Berker
Turkish Journal of Chemistry
A rapid, easy, and reproducible method for the simultaneous determination of inorganic anions and organic acids is reported. The method is based on the separation of anions in a capillary coated with a cationic polymer, polyethyleneimine (PEI). Four inorganic anions (chloride, sulfate, iodate and phosphate) and eight organic acids (oxalate, tartarate, malate, succinate, citrate, acetate, lactate, and propionate) were separated and quantified within 7 min by using 2,6-pyridinedicarboxylic acid (PDC) as the background electrolyte. The minimum detection limits are 0.67-2.87 \mu g/mL for inorganic ions and 0.38-2.84 \mu g/mL for organic acids. Reproducibilities in migration times (RSD%) for both inorganic …
Analysis Of Polychlorinated Dibenzofurans (Pcdfs) Isomers In Soil Samples, Mustafa Pehli̇van, Erol Pehli̇van
Analysis Of Polychlorinated Dibenzofurans (Pcdfs) Isomers In Soil Samples, Mustafa Pehli̇van, Erol Pehli̇van
Turkish Journal of Chemistry
This study presents an analytical method for the separation of a series of polychlorinated dibenzofurans (PCDFs) emitted to the soil. PCDF contaminants were concentrated from soil samples and isolated from other materials by chromatographic methods and their quantitative determinations were performed by GC/MS (gas chromatography/mass spectroscopy).
Usefulness Of A Technique Based On Negative Corona Discharge For The Degradation Of Selected, Condensed Pahs: Application To The Oxidation Of Anthracene And Similar Structures, D. Tessi̇er, C. Oguic, J. Pinart, J. J. Aaron
Usefulness Of A Technique Based On Negative Corona Discharge For The Degradation Of Selected, Condensed Pahs: Application To The Oxidation Of Anthracene And Similar Structures, D. Tessi̇er, C. Oguic, J. Pinart, J. J. Aaron
Turkish Journal of Chemistry
The usefulness of negative corona discharge for oxidation of condensed polycyclic aromatic hydrocarbons (PAHs), including anthracene, naphthalene and 2,3-benzanthracene, adsorbed on a solid substrate is evaluated. In the case of anthracene, the application of corona discharge under high voltage (10-20 kV) for 10 to 180 min with a current intensity of 5-120 \mu A in a controlled, humid atmosphere leads to the progressive formation of anthraquinone. A kinetic study of the anthracene oxidation shows that the apparent half-lives range from 5 to 48 min, according to the initial anthracene amount (50-5000 nmol), indicating a reaction order between 0 and 1. …