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Öğe C2-Symmetric chiral diamine ligands for enantiomeric recognition of amino acid esters and mandelic acid by proton NMR titration method(Tubitak Scientific & Technological Research Council Turkey, 2013) Aral, Hayriye; Aral, Tarik; Colak, Mehmet; Ziyadanogullari, Berrin; Ziyadanogullari, RecepTwo novel C-2-symmetric chiral diamines containing alpha-phenylethyl and alpha-(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 H-1 NMR titration method. These ligands exhibited strong complexation (with K-f up to 2481 M-1) and good enantioselectivity (up to K-L/K-D = 4.08) towards the mandelic acid enantiomers. The results show that simple structured and easily accessible acyclic C-2-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 $C_2$-symmetric chiral diamine ligands for enantiomeric recognition of amino acid esters and mandelic acid by proton NMR titration method(2013) Aral, Tar K; Olak, Mehmet C; Gulları, Berrin Ziyadano; Aral, Hayriye; Gulları, Recep ZiyadanoTwo novel $C_2$ -symmetric chiral diamines containing $alpha$ -phenylethyl and $alpha$-(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 $K_f$ up to 2481 $M^{-1}$) and good enantioselectivity (up to $K_L$ /$K_D$ = 4.08) towards the mandelic acid enantiomers. The results show that simple structured and easily accessible acyclic $C_2$-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) Aral, Hayriye; Aral, Tarik; Ziyadanogullari, Berrin; Ziyadanogullari, RecepA novel amide-bonded silica stationary phase was prepared starting from N-Boc-phenylalanine, cyclohexylamine and spherical silica gel (4 mu m, 60 angstrom). 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 degrees C column temperature. Under these experimental conditions, the 12 phytohormones could be separated and detected at 230 or 270 nm within 26 min. (C) 2013 Elsevier B.V. All rights reserved.Öğe Farklı polaritelere sahip amid-silika kolon dolgu materyallerinin sentezi ve HPLC ile çeşitli polar bileşiklerin ayrılmasında kullanılması(2015) Aral, HayriyeSon zamanlarda yapılan çalışmalara bakıldığında polar gruplar içeren dolgu maddeleriyle yapılan çalışmaların, bu dolgu maddelerinin yaygın olarak kullanılan geleneksel fazlar olan C8 ve C18 fazlarına göre bazik analitlere karşı çok daha iyi ayırma sağladığını göstermiştir. Polar gruplar, özellikle amidler, bazik analitlerle güçlü etkileşim yapabilmelerinden dolayı tercih edilir. Ayrıca amid grubu içeren dolgu fazları, düşük molekül ağırlıklı asitlere karşı da üstün bir seçicilik gösterir (Ascah ve ark. 1996). Bu çalışmada iki adet silika tabanlı amid türevi yeni dolgu maddesi elde edildi. Bu amitlerden birisi N-Boc-Fenilalanin, sikloheksil amin ve küresel silika jel (4mµ, 60 Å); diğeri ise N-Boc-Glutamin, anilin ve küresel silika jel (4mµ, 60 Å) kullanılarak elde edildi. Her iki sentezin ilk basamağı (amit sentezi) DCC ortamında gerçekleştirildi. Daha sonra her iki amid bileşiğinin boc grubu TFA/CH3COOH ortamında kaldırıldı. Bunlardan N-Boc-Fenilalanin ve siklohekzilaminden elde edilen boc grubu kaldırılmış bileşik 3-kloropropiltrimetoksisilan (CPTMS) ile uyarlanmış küresel silika jel ile etkileştirilerek SP1 kodlu dolgu fazı hazırlandı. Öte yandan N-Boc-Glutamin ve anilinden elde edilen boc koruyucu grubu kaldırılmış bileşik 3-glisidiloksipropiltrimetoksisilan (GPTMS) ile etkileştirildi ve daha sonra küresel silika jel ile reaksiyona sokularak SP2 kodlu dolgu fazı hazırlandı. Her iki dolgu maddesinin yapısı element analizi, SEM ve IR ile tayin edildi. Bu dolgu fazları geleneksel bulamaç paketleme metodu ile yüksek basınç altında HPLC boş kolonuna dolduruldu. Kolonlar on üç bitki büyüme düzenleyicisi, on bir fenolik bileşik, on sübstitüe anilin, çeşitli nükleotid ve nükleozitler ve sudan boyalarının ayrılmasında kullanıldı. Dolgu maddelerinin özelliklerini ve ayırma gücünü incelemek için mobil faz içeriği, pH, tampon derişimi, akış hızı, sıcaklık gibi şartlara karşı ayrıntılı optimizasyon çalışmaları yapıldı. SP1'in özellikle bitki büyüme düzenleyicilerine karşı SP2'nin de nükleotid ve nükleozidlere karşı piyasadaki mevcut ticari kolonlarla yarışacak ölçüde performans gösterdiği tespit edildi.Öğe HPLC Separation of Different Groups of Small Polar Compounds on a Novel Amide-Embedded Stationary Phase(Springer Heidelberg, 2014) Aral, Hayriye; Aral, Tarik; Celik, K. Serdar; Ziyadanogullari, Berrin; Ziyadanogullari, 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 Preparation of a novel ionic hybrid stationary phase by non-covalent functionalization of single-walled carbon nanotubes with amino-derivatized silica gel for fast HPLC separation of aromatic compounds(Elsevier Science Bv, 2016) Aral, Hayriye; Celik, K. Serdar; Aral, Tarik; Topal, GiraySingle-walled carbon nanotubes (SWCNTs) were immobilized on spherical silica gel with a 4-mu m average particle size and a 60-angstrom average pore size. The amino-derivatized silica gel was non-covalently coated with carboxylated SWCNTs to preserve the structure of the nanotubes and their physico-chemical properties. The novel ionic hybrid stationary phase was characterized by scanning electron microscopy (SEM), infra-red (IR) spectroscopy and elemental analysis, and then, it was used to fill an empty 150 x 4.6 mm(2) high-performance liquid chromatography (HPLC) column. Chromatographic parameters, such as the theoretical plate number, retention factor and peak asymmetry factor, and analytical parameters, such as the limit of detection (LOD), limit of quantification (LOQ), linear range, calibration equation, and R-2 value, and quantitative analysis parameters were calculated for all of the analytes. Using different mobile phases, five different classes of aromatic hydrocarbons were separated in a very short analysis time of 4-8 min. Furthermore, a high theoretical plate number (up to 25000) and an excellent peak asymmetry factor (1.0) were obtained. The results showed that the surface of the SWNTs had very strong interactions with aromatic groups, therefore providing high selectivity for the separation of different classes of aromatic compounds. This study indicates that SWCNTs enable the extension of the application range of the newly prepared stationary phases for the fast separation of aromatic compounds by HPLC. (C) 2015 Elsevier B.V. All rights reserved.Öğe Separation, optimization, and quantification of cytokinins by a recently developed amide-embedded stationary phase(Taylor & Francis Inc, 2017) Aral, Hayriye; Hasimi, Duygu; Aral, Tarik; Levent, Abdulkadir; Ziyadanogullari, BerrinIn this study, some plant growth regulators known as cytokinins [kinetin (K), zeatin (Z), thidiazuron (TDZ), benzylaminopurine (BAP), and dimethylallylaminopurine (AAP)] were separated by HPLC using an amide-embedded mixed-mode stationary phase which was synthesized by Aral et al. in recent years. The effect of mobile phase content, mobile phase pH, buffer concentration, and temperature on separation process was studied. In addition, a quantitative determination of cytokinins from Salvia limbata extract was studied, and some validation parameters such as limit of detection (LOD), limit of quantification (LOQ), and relative standard deviation (RSD) were calculated as a range of 0.03-0.1, 0.1-0.26mg/L, and 0.03-0.08, respectively. [GRAPHICS] .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 Science Bv, 2015) Aral, Tarik; Aral, Hayriye; Ziyadanogullari, Berrin; Ziyadanogullari, RecepA novel mixed-mode stationary phase was synthesised starting from N-Boc-glutamine, aniline and spherical silica gel (4 mu m, 60 angstrom). 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 degrees 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 degrees 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 degrees 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 degrees C column temperature and seven phenolic compounds could be separated and detected at 230 nm within 16 min. (C) 2014 Elsevier B.V. All rights reserved.
