Tufan Güray

Tufan Güray
Eskisehir Osmangazi University | ESOGU · Department of Chemistry

Prof. Dr.

About

33
Publications
10,475
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204
Citations
Additional affiliations
December 1996 - present
Eskisehir Osmangazi University
Position
  • Öğretim Üyesi
Education
September 1989 - June 1995
Anadolu University
Field of study
  • Chemistry

Publications

Publications (33)
Article
Full-text available
A capillary zone electrophoretic method for the determination of zearalenone is described in this study. In the separation, a run buffer consisting of 20 mM sodium tetraborate at pH 9.0 with 15% acetonitrile applying 15 kV, injecting 10 s at 50 mbar was utilized. Phenobarbital was a suitable internal standard and the signals were recorded at 254 nm...
Article
This study was undertaken for screening biological activity of Azadirachta indica A. Juss. growing in Somalia. The study was aimed to investigate the biological activity namely: antioxidant activity, total phenol content, total flavonoid content and as well as its Phytochemical composition, 43mg of essential oils (EOs) were extracted from 65g of ai...
Article
Ultrasound-assisted cloud point microextraction (UA-CPME) was performed for certain preservatives (p-hydroxy benzoic acid and its alkyl esters, methyl, ethyl, propyl and butyl parabens). Then, an HPLC method was developed for their simultaneous determination in pharmaceutical and cosmetic samples. The chromatograms of these substances were recorded...
Article
HPLC method after ultrasound assisted cloud point micro extraction (UA-CPME) for the simultaneous determination of p-hydroxy benzoic acid and its alkyl esters, methyl, ethyl, propyl and butyl paraben, which are widely used as preservatives in drug and cosmetic product was developed in this study. The chromatograms of these substances were recorded...
Article
Full-text available
In this study, a Schiff base called (E)-2-((2- hydroxy -3- methoxy benzylidene)amino)-5- methylphenol (L) was used as a ligand. Spectrophotometric properties of the ligand have been defined and the optimum conditions for determining aluminium by complex by UV-Vis. spectrophotometry. The absorbance of Al(III)-L complex obeys Beer’s law between 1.4 µ...
Article
Full-text available
zet: Bu makalede, nikel tayini için, herhangi bir ön deriştirme işlemi uygulamadan, pH 5,5 (5-6) 'da 2,3,4,6 /-tetrahidroksi-3 /-sülfoazobenzen (THSA) ile şelat oluşturarak seçici ve duyarlı bir spektrofotometrik yöntem önerilmiştir. Metal ligand oranı 1: 1 olan kompleksin, 485 nm'de, molar absorplama katsayısı 1,60 ×10 4 L mol −1 cm −1 'dir. Kompl...
Article
Full-text available
Abstract: In this article, a selective and sensitive spectrophotometric by chelating with 2,3,4,6/-tetrahydroxy-3/-sulfoazobenzene (THSA) at pH 5.5 (5-6) without applying any preconcentration process for nickel determination method is proposed. A selective and sensitive spectrophotometric method has been proposed for the determination of nickel by...
Article
Full-text available
This paper reports a new and validated capillary electrophoresis method to determine Roflumilast (RFL) with an internal standard in tablet. The separation was made on an uncoated fused-silica capillary column 50 cm effective length and 75 µm i.d. 20 mmol L-1 of Na2B4O7 buffer including 15% (v/v) methanol (pH=9.5) was used as background electrolyte....
Article
Full-text available
A simple and validated micellar electrokinetic chromatographic method is described for the determination of 5-hydroxymethylfurfural (HMF). The method was applied to fresh and processed (heated at 65 °C, 85 °C and 105 °C for 5 h and 20 h) multifloral and honeydew honeys. Optimum conditions were: 10 mmol L−1 Tris buffer consisting 110 mmol L−1 SDS an...
Article
Full-text available
z Ponceau 4R (E-124) özellikle gıda ve ilaç sanayisinde sıklıkla kullanılan bir gıda boyasıdır. Bu çalışmada, Ponceau 4R'nin bulut noktası ekstraksiyonu için non iyonik bir yüzey aktif madde olan Brij 58 kullanılarak ön deriştirme ve ayırma işlemi gerçekleştirilmiştir. Bu ön deriştirme işlemi sonrasında Ponceau 4R spektrofotometrik tayini yapılmışt...
Article
Full-text available
A selective and sensitive spectrophotometric method has been proposed for the determination of copper by forming red-brown chelate at pH 3.5 (3-4) with 2,3,4,6 /-tetrahydroxy-3 /-sulfoazobenzene (THSA). Molar absorptivity of the complex having metal ligand ratio of 1:2 is 4.03 × 10 4 L mol −1 cm −1 at 485 nm. Its conditional stability constant (log...
Article
Full-text available
Abstract: In this study, Brij 58 was used for the spectrophotometric determination of sunset yellow (SY) (E-110) in pharmaceutical preparations and powdered beverages after cloud point extraction (CPE). Certain parameters such as pH, surfactant concentration, extraction time and temperature, speed of centrifugation, and salt concentration were opti...
Article
Full-text available
A selective and sensitive spectrophotometric method has been proposed for the determination of copper by forming red-brown chelate at pH 3.5 (3-4) with 2,3,4,6/-tetrahydroxy-3/-sulfoazobenzene (THSA). Molar absorptivity of the complex having metal ligand ratio of 1:2 is 4.03 × 10⁴ L mol⁻¹ cm⁻¹ at 485 nm. Its conditional stability constant (log K) i...
Article
Full-text available
A selective and sensitive spectrophotometric method has been proposed for the determination of copper by forming red-brown chelate at pH 3.5 (3-4) with 2,3,4,6 /-tetrahydroxy-3 /-sulfoazobenzene (THSA). Molar absorptivity of the complex having metal ligand ratio of 1:2 is 4.03 × 10 4 L mol −1 cm −1 at 485 nm. Its conditional stability constant (log...
Article
Full-text available
Indacaterol is a new inhaled ultra-long acting β2-agonist. It has been recently approved in the European Union for the treatment of chronic obstructive pulmonary disease. This paper reports, for the first time, a method for the determination and validation of Indacaterol (IND) using an internal standard in capsules. Capillary electrophoretic separa...
Article
Full-text available
A validated rapid and sensitive capillary zone electrophoretic method for the determination of olopatadine hydrochloride is described. Optimum conditions were found: 20 mmol/L sodium tetraborate buffer, 15% (v/v) ACN, 10 mmol/L NaCl at pH=9.5 in the use of 25 kV of applied potential; 10 s at 5×103 N/m2 of injection time; and 205 nm of wavelength an...
Article
Full-text available
A validated liquid chromatography method employing a fluorescence detector for the determination of ochratoxin A (OTA) was developed with double internal standard and it was applied to ten different poultry feeds. The analysis was performed in an octadecyl silane column using a solvent system [ACN:water:formic acid (50:50:1.25, v/v/v)] by isocratic...
Article
Full-text available
A validated liquid chromatography method employing a fluorescence detector for the determination of ochratoxin A (OTA) was developed with double internal standard and it was applied to ten different poultry feeds. The analysis was performed in an octadecyl silane column using a solvent system [ACN:water:formic acid (50:50:1.25, v/v/v)] by isocratic...
Article
A validated liquid chromatography method employing a fluorescence detector for the determination of ochratoxin A (OTA) was developed with double internal standard and it was applied to ten different poultry feeds. The analysis was performed in an octadecyl silane column using a solvent system [ACN:water:formic acid (50:50:1.25, v/v/v)] by isocratic...
Article
Full-text available
A capillary zone electrophoretic method for the determination of zearalenone is described in this study. In the separation, a run buffer consisted of 20 mM sodium tetraborate at pH 9.0 with 15 % acetonitrile applying 15 kV, injecting 10 s at 50 mbar was utilized. Phenobarbital was a suitable internal standard and the signals were recorded at 254 nm...
Article
Full-text available
This study describes a capillary zone electrophoretic method for the determination of patulin. An optimum run buffer was found to be 25 mM of sodium tetraborate and 10% acetonitrile (v/v) at pH 10. Optimum conditions were determined to be: an applied voltage of 25 kV (normal polarity), temperature of 25°C and injection time of 10 s at 50 mbar; the...
Article
Full-text available
In this study, 2, 2', 3, 4-tetrahydroxy-3'-sulpho-5'-carboxyazobenzene (tetrahydroxyazon SC) has been synthesized for the first time and used for direct spectrophotometric determination of zirconium(IV). Tetrahydroxyazon SC in a 5.0 M acidic medium (up to pH 6) with zirconium(IV) gave a red complex (Zr-tetrahydroxyazon SC), which has maximum absorp...
Article
Full-text available
A novel azo derivative, 2,3,4,6 -tetrahydroxy-3 -sulfoazobenzene (THSA), was synthesized by using pyrogallol. The acid dissociation constants, or K a values, of THSA were determined by the UV-visible spectroscopic technique. The protonation and deprotonation behaviors of the title molecule were studied from the super basic to the super acid region...
Article
Full-text available
A validated capillary electrophoresis method for the determination of parabens-methyl, ethyl, propyl, and butyl is described. The optimum results were obtained by the use of a run buffer containing 20 mM borate buffer (pH 9.0) with 10% methanol and by applying a voltage of 20 kV, a low hydrodynamic injection of 10 s, and detecting the signals at 20...
Article
Full-text available
2,2',3,4-Tetrahydroxy-3',5'-disulphoazobenzene (tetrahydroxyazon 2S) has been synthesized for the first time. This reagent has been used for the spectrophotometric determination of aluminium and indium ions. The method is very sensitive and selective for the direct determination of aluminium and indium. The optimum pH and absorbance of complexes fo...
Article
Full-text available
The acidity constants, pK(a) values for protonation of some substituted thiazole derivatives were calculated by using AM1 and PM3 basis sets of semi-empirical methods and B3LYP/6-31G(d) basis sets of density functional theory (DFT) calculated physical and thermodynamic parameters. Correlation search among the experimental and calculated acidity con...
Article
Full-text available
A selective and sensitive new spectrophotometric method has been developed for the determination of aluminium. 2,2′,3,4-Tetrahydroxy-3′-sulpho-5′-nitroazobenzene (tetrahydroxyazon SN) formed an orange chelate with aluminium at pH 4. Molar absorptivity of the complex in 1:2 is 5.46 × 104 l mol−1 cm−1 at 479 nm. The method obeys Beer's law in the ran...
Article
Full-text available
The thermodynamic properties of some oxazolo[4,5-b]pyridin derivatives were calculated by semiempirical AM1 quantum chemical calculation method and any possible parallelism with the reported experimental data were searched. Some acceptable correlations between the calculated and experimental properties were detected. The theoretically calculated ac...

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