7 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 7 / 7
Öğe Yeni bir amid silika dolgu maddesinin sentezi ve hidrofilik etkileşim sıvı kromatografisi (HILIC) uygulamaları(Mustafa Kemal Üniversitesi, 2012-09) Aral, Tarık; Aral, Hayriye; Ziyadanoğulları, Berrin; Ziyadanoğulları, RecepÖğe HPLC separation of different groups of small polar compounds on a novel amide-embedded stationary phase(Elsevier, 2014-05-10) Aral, Hayriye; Aral, Tarık; Çelik, Kadir Serdar; Ziyadanoğulları, Berrin; Ziyadanoğulları, RecepRetention behaviors of an amide-embedded silica base stationary phase, which was recently developed by our group, were studied by using six different groups of small polar compounds including phenolic compounds, substituted anilines, chlorinated herbicides, Sudan dyes and some nucleotides and nucleosides in HPLC. The chromatographic behaviors of the prepared stationary phase for these analytes were compared with those of a commercially available reversed-phase column ACE C18 under same conditions. Among the six groups of analytes studied, the amide-silica stationary phase showed enhanced selectivity towards phenolic compounds, substituted anilines, Sudan dyes and herbicides under reversed-phase conditions and satisfactory selectivity towards nucleosides and nucleotides which could not be separated with ACE C18 column under HILIC conditions. Experimental data provided some evidence that functional groups on the stationary phases might have certain degrees of influence on selectivity possibly through secondary interactions with the model compounds. The retentions of the moderately polar compounds such as phenolic acids, anilines and herbicides on the stationary phase are higher than highly polar compounds such as nucleotides and nucleosides due to both the hydrophobic and hydrophilic interactions between the stationary phase and analytes. The quantitative determination of Sudan dyes (I, II, III, and IV) in red chilli peppers was performed. Many red chilli peppers were screened and three of them contained Sudans dyes.Öğe Synthesis of a mixed-model stationary phase derived from glutamine for HPLC separation of structurally different biologically active compounds: HILIC and reversed-phase applications(Elsevier, 2015-01) Aral, Tarık; Aral, Hayriye; Ziyadanoğulları, Berrin; Ziyadanoğulları, RecepA novel mixed-mode stationary phase was synthesised starting from N-Boc-glutamine, aniline and spherical silica gel (4 μm, 60 Å). The prepared stationary phase was characterized by IR and elemental analysis. The new stationary phase bears an embedded amide group into phenyl ring, highly polar a terminal amide group and non-polar groups (phenyl and alkyl groups). At first, this new mixed-mode stationary phase was used for HILIC separation of four nucleotides and five nucleosides. The effects of different separation conditions, such as pH value, mobile phase and temperature, on the separation process were investigated. The optimum separation for nucleotides was achieved using HILIC isocratic elution with aqueous mobile phase and acetonitrile with 20 °C column temperature. Under these conditions, the four nucleotides could be separated and detected at 265 nm within 14 min. Five nucleosides were separated under HILIC isocratic elution with aqueous mobile phase containing pH=3.25 phosphate buffer (10 mM) and acetonitrile with 20 °C column temperature and detected at 265 nm within 14 min. Chromatographic parameters as retention factor, selectivity, theoretical plate number and peak asymmetry factor were calculated for the effect of temperature and water content in mobile phase on the separation process. The new column was also tested for nucleotides and nucleosides mixture and six analytes were separated in 10 min. The chromatographic behaviours of these polar analytes on the new mixed-model stationary phase were compared with those of HILIC columns under similar conditions. Further, phytohormones and phenolic compounds were separated in order to see influence of the new stationary phase in reverse phase conditions. Eleven plant phytohormones were separated within 13 min using RP-HPLC gradient elution with aqueous mobile phase containing pH=2.5 phosphate buffer (10 mM) and acetonitrile with 20 °C column temperature and detected at 230 or 278 nm. The best separation conditions for seven phenolic compounds was also achieved using reversed-phase HPLC gradient elution with aqueous mobile phase containing pH=2.5 phosphate buffer (10 mM) and acetonitrile with 20 °C column temperature and seven phenolic compounds could be separated and detected at 230 nm within 16 min.Öğe Development of a novel amide silica stationary phase for the reversed phase HPLC separation of different classes of phytohormones(Journals & Books, 2013-05-14) Aral, Tarık; Aral, Hayriye; Ziyadanoğulları, Berrin; Ziyadanoğulları, RecepA novel amide-bonded silica stationary phase was prepared starting fromN-Boc-phenylalanine, cyclo-hexylamine and spherical silica gel (4mm, 60 Å). The amide ligand was synthesised with high yield. Theresulting amide bonded stationary phase was characterised by SEM, IR and elemental analysis. Theresulting selector bearing a polar amide group is used for the reversed-phase chromatography separationof different classes of thirteen phytohormones (plant hormones). The chromatographic behaviours ofthese analytes on the amide-silica stationary phase were compared with those of RP-C18 column undersame conditions. The effects of different separation conditions, such as mobile phase, pH value,flow rateand temperature, on the separation and retention behaviours of the 13 phytohormones in this systemwere studied. The optimum separation was achieved using reversed-phase HPLC gradient elution with anaqueous mobile phase containing pH¼6.85 potassium phosphate buffer (20 mM) and acetonitrile with a221C column temperature. Under these experimental conditions, the 12 phytohormones could beseparated and detected at 230 or 270 nm within 26 minÖğe C2-Symmetric chiral diamine ligands for enantiomeric recognition of amino acid esters and mandelic acid by proton nmr titration method(TÜBİTAK, 2013-07-08) Aral, Hayriye; Aral, Tarık; Çolak, Mehmet; Ziyadanoğulları, Berrin; Ziyadanoğulları, RecepTwo novel C2 -symmetric chiral diamines containing α-phenylethyl and α-(1-naphthyl)ethyl chiral subunits were prepared with quantitative yields. Enantiomeric recognition properties of these simple structured diamine ligands towards D- and L-amino acid esters and D- and L-mandelic acid were examined by the 1H NMR titration method. These ligands exhibited strong complexation (with Kf up to 2481 M-1) and good enantioselectivity (up to KL /KD = 4.08) towards the mandelic acid enantiomers. The results show that simple structured and easily accessible acyclic C2 -symmetrical compounds can also be used for enantiomeric recognition of racemic amino acids and mandelic acid in addition to complex molecules such as crown ethers and other cyclic molecules.Öğe Development of a novel amide-silica stationary phase for the reversed-phase HPLC separation of different classes of phytohormones(Elsevier, 2013-11) Aral, Hayriye; Aral, Tarık; Ziyadanoğulları, Berrin; Ziyadanoğulları, RecepA novel amide-bonded silica stationary phase was prepared starting from N-Boc-phenylalanine, cyclohexylamine and spherical silica gel (4 μm, 60 Å). The amide ligand was synthesised with high yield. The resulting amide bonded stationary phase was characterised by SEM, IR and elemental analysis. The resulting selector bearing a polar amide group is used for the reversed-phase chromatography separation of different classes of thirteen phytohormones (plant hormones). The chromatographic behaviours of these analytes on the amide-silica stationary phase were compared with those of RP-C18 column under same conditions. The effects of different separation conditions, such as mobile phase, pH value, flow rate and temperature, on the separation and retention behaviours of the 13 phytohormones in this system were studied. The optimum separation was achieved using reversed-phase HPLC gradient elution with an aqueous mobile phase containing pH=6.85 potassium phosphate buffer (20 mM) and acetonitrile with a 22 C column temperature. Under these experimental conditions, the 12 phytohormones could be separated and detected at 230 or 270 nm within 26 min.Öğe Amid-silika türevi yeni bir kolon dolgu materyalinin sentezi ve normal faz sıvı kromatografisi ile bitki büyüme düzenleyicilerinin ayrılması(Mustafa Kemal Üniversitesi, 2012-09) Aral, Tarık; Aral, Hayriye; Ziyadanoğulları, Berrin; Çelik, Kadir Serdar; Ziyadanoğulları, Recep
