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Öğe A Critical Study on the Potential of Solid-Phase Fluorescence Spectroscopy (SPFS) in Quantitative Analysis: Effect of Solid Diluent and Sampling Method on Signal Quality(Oxford Univ Press Inc, 2023) Ozturk, Merve; Gezici, OrhanBackground Solid-phase fluorescence spectroscopy (SPFS) is a very useful non-destructive technique for directly analyzing samples in solid form without the use of solvents. However, due to the so-called inner-filter effect, it is sometimes necessary to dilute solid samples using non-fluorescent solids as diluents. Objective This study aimed to explore the potential of SPFS in the quantitative analysis of fluorescent species based on: (1) the type of solid diluent; and (2) the sampling method used in the SPFS analysis. Methods Four different solids were used as solid diluents in the preparation of standard mixtures having different concentrations of rhodamine b and fluorescein as model compounds. Standard mixtures of model compounds were sampled by two different methods called: (1) the powder-cell method; and (2) the adhesive tape method. LOQ and calibration sensitivity calculated from the calibration graphs were used to assess the measurement performance. The usability of SPFS in real-sample analyses was also evaluated in detail. Results Among the solid diluents studied, the best results were obtained with sodium carbonate. The powder-cell method yielded a significant advantage over the adhesive tape method. The lowest LOQs for rhodamine b and fluorescein were obtained by sodium carbonate and the powder-cell method as 0.06 mg/kg and 0.11 mg/kg, respectively. The results of real-sample analyses were verified using conventional liquid-phase fluorescence spectroscopy (LPFS). Conclusion Solid-diluent type and sampling method were found to affect the performance of the SPFS technique. A combination of sodium carbonate and the powder-cell method gave the best results. According to the t-test, no difference was observed between the means obtained by SPFS and LPFS techniques in real-sample analyses.Öğe Adsorption of nitroaniline positional isomers on humic acid-incorporated monolithic cryogel discs: Application of ligand-exchange concept(Elsevier Sci Ltd, 2017) Senlik, Kadir; Gezici, Orhan; Guven, Idris; Pekacar, Ali IhsanAdsorptive removal of some nitroaniline positional isomers was studied by using a humic acid-cryogel based monolithic adsorbent (MLHA). Monolithic material was characterized by FTIR and SEM techniques. The adsorbent was turned into a ligand exchanger form (i.e. Cu-MLHA) by Cu(II) loading. The amount of Cu( II) bound to the monolithic discs was determined by AAS analyses. The effect of contact time and initial nitroaniline concentration on adsorption was studied, and the fit of some isotherm models was analyzed. Maximum observable adsorption capacities recorded on Cu- MLHA were found to be around 150-180mg/g, and the capacities decreased in the order 3-nitroaniline > 4-nitroaniline > 2-nitroaniline.Öğe Adsorptive removal of Methylene blue and Methyl orange from aqueous media by carboxylated diaminoethane sporopollenin: On the usability of an aminocarboxilic acid functionality-bearing solid-stationary phase in column techniques(ELSEVIER SCIENCE BV, 2007) Ayar, Ahmet; Gezici, Orhan; Kucukosmanoglu, MuhittinThe adsorption phenomena of Methylene blue (MB) and Methyl orange (MO) on a carboxylated diaminoethane sporopollenin (CDAE-S) solid phase were investigated in a column arrangement by using breakthrough technique. The adsorption phenomena were evaluated using some common adsorption isotherm models and Scatchard plot analysis, and obtained results were interpreted for evaluating the usability of CDAE-S for removal, recovery and preconcentration of the studied dyes both at the laboratory and industrial scales. On the basis of Scatchard plot analysis, the interaction types between the CDAE-S and the studied dyes were criticized in terms of affinity phenomena. Thus, the usability of a biomacromolecule-derived material, CDAE-S, as a cheap, environmentally-friendly and effective solid-stationary phase exhibiting both cation-exchange and anion-exchange characteristics at the same time, is discussed through the present study. Besides, from the obtained results, the protonated CDAE-S, which functionally resembles an amino acid structure, are presented as a two-in-one solid- stationary phase, and its adaptability to common processes performed under column conditions is also drawn in detail. (C) 2006 Elsevier B.V. All rights reserved.Öğe An Application of a Schiff-Base Type Reaction in the Synthesis of a New Rhodamine-Based Hg(II)-Sensing Agent(Springer/Plenum Publishers, 2019) Cicekbilek, Fulya; Yilmaz, Bahar; Bayrakci, Mevlut; Gezici, OrhanA facile synthesis procedure, whereby 9-Anthraldehyde (AA) is coupled to aminated rhodamine (AR) via a Schiff base-type reaction, is reported. The applicability and performance of the obtained material (AA-AR) as a sensing agent was studied towards 16 metal cations (i.e. Li+, Na+, Ag+, Ca2+, Ba2+, Co2+, Cs+, Cu2+, Mg2+, Hg2+, Mn2+, Pb2+, Ni2+, Sr2+, Zn2+, Al3+). Among the studied metals, an extraordinary selectivity was observed for Hg2+, and the observed selectivity was found not to be influenced by the presence of other cations and some common anions (i.e. Br-, Cl-, I-, HPO42-, H2PO4-, NO3-, NO2-, ClO4-, AcO-, HSO4-, SO42-, Cr2O7-, CO32-, OH- and HCO3-). The material, AA-AR, exhibited such a high selectivity and sensitivity towards Hg2+ that it could be detected even by naked eyes. The Hg2+-sensing property of AA-AR was found not to be limited to colorimetric detections so that a high fluorescent nature of the compound was also observed upon binding Hg2+ ion. The detection limit, which is correspondent to fluorescence emission intensity, was found as 0.87 mu M. The underlying mechanism of sensing property was studied by using some spectroscopic techniques such as FT-IR, H-1-NMR, C-13-NMR, and UV-Vis. (Job-plot). In the final course of the experiments, the performance of AA-AR in cell-imaging was also studied, and even trace amounts of Hg2+ in living cells could be detected by the studied probe. Thus, the applicability of a new synthesis approach in producing a highly efficient new fluorescence sensor for the detection of Hg2+ ions is discussed in detail.Öğe An Application of a Schiff-Base Type Reaction in the Synthesis of a New Rhodamine-Based Hg(II)-Sensing Agent (vol 29, pg 1349, 2019)(Springer/Plenum Publishers, 2020) Cicekbilek, Fulya; Yilmaz, Bahar; Bayrakci, Mevlut; Gezici, Orhan[Abstract Not Available]Öğe An Application of Polydopamine-dip Coating as a Gentle Surface Modification Process for Cryogel Disks(2020) Özbek, Gözde; Gezici, Orhan; Bayrakcı, MevlütThe process called “polydopamine-dip coating” was successfully applied to modify the surface of poly(2-hydroxyethyl methacrylate), PHEMA, cryogel disks for the first time. This facile surface modification process fitted very well to the chemistry of cryogels since the integrity of the cryogel disks was maintained during the whole process. Polydopamine (PDA) nanocoating process was observed to be homogeneously performed through the pores and there was a net color change from white to brown after 24 h. The obtained (brownish) material (PHEMA-PDA) was characterized with respect to FTIR spectroscopy, pHpzc, and water-holding capacity analyses. The potential of this new material was studied by utilizing it as an adsorbent for the adsorption of Ni(II) from synthetic aqueous solutions. The equilibrium adsorption data were analyzed on the basis of the Langmuir, the Freundlich, and the Temkin isotherm models. In general, Ni(II) adsorption on PHEMA-PDA was evaluated as a favorable process as depicted from the studied models. The proposed approach was found to be a promising post- surface modification process for tailoring the surface of monolithic cryogels without any difficult synthesis steps and harsh chemicals.Öğe Calixarene-engineered surfaces and separation science(SPRINGER, 2015) Gezici, Orhan; Bayrakci, MevlutAfter their discovery, calixarenes have attracted the attention of many researchers from various disciplines. This group of supramolecules has an increasing popularity and this is most probably related with the flexibility of calixarene chemistry. Owing to their multifunctional character and stability, calixarenes became important precursors in separation science to derive new-type of sorbents or stationary phases. Immobilization of calixarenes to a suitable solid support (e.g. silica, synthetic polymers, magnetite nanoparticles, etc.) is a very popular concept being used for this purpose, and various immobilization methodologies have been proposed in the literature. In the present work, some state-of-the-art researches and developments published in the past are reviewed in a collective manner, and thus fundamentals of calixarene-immobilization and the application of the obtained materials in sorption and high performance liquid chromatography are represented.Öğe Generation of a pH-blind/pH-sensitive alternating surface on a hydrophobic resin by mussel-inspired chemistry and investigating the effect of surface modification on the adsorption dynamics of some anionic colorants(Springer, 2021) Gezici, Orhan; Bisgin, Abdullah TanerThe effect of a surface modification process known as mussel-inspired modification on the adsorption dynamics of hydrophobic adsorbent, namely XAD1180, was studied based on equilibrium adsorption data. In the study, three anionic colorants (i.e., Sunset yellow, SY; Allura red, AR; and Tartrazine, TZ) were used as the model compounds. The role of some experimental parameters, such as pH (4-7), ionic strength (0.01-0.50 mM) and colorant concentration (25-125 mg/L), were investigated to determine optimal conditions leading to the highest adsorption. Equilibrium adsorption data were obtained under optimal conditions by stepwise frontal analysis method (SFA) and modeled on the basis of some common adsorption isotherm models (i.e., Langmuir and Freundlich). The adsorption dynamics of the XAD1180 resin have been found to vary significantly after PD coating. After the PD coating process, it was found that the highly hydrophobic background material, XAD1180, gained a pH-sensitive character, thereby replacing a sharp decrease in the adsorption capacity at pH=5.0-7.0 with an increase in pH=4.0. Another dramatic effect of the PD coating was observed with Langmuir monolayer adsorption capacities, so that the PD layer was found to increase the monolayer saturation capacity of the XAD1180 (from 8.0 to 17 mu mol/g for SY, from 7.7 to 9.9 mu mol/g for AR, and from 5.3 to 9.1 mu mol/g for TZ). It was also deduced from the Freundlich isotherm parameter, K-F, that there was, in general, a clear increment in the overall effect of adsorption capacity and the average affinity after mussel-inspired surface modification process.Öğe Humic-makeup approach for simultaneous functionalization of polyacrylonitrile nanofibers during electrospinning process, and dye adsorption study(TAYLOR & FRANCIS INC, 2016) Gezici, Orhan; Guven, Idris; Ozcan, Fatih; Ertul, Seref; Bayrakci, MevlutA useful methodology is represented to functionalize polyacrylonitrile nanofibers by using humic acid as a makeup agent in electrospinning process. Both morphology and surface chemistry of polyacrylonitrile nanofiber mats were understood to be influenced by incorporation of humic acid into the structure. Physicochemical changes were evidenced by Fourier transform infrared spectroscopy, scanning electron microscope, and surface charge measurements. Unlike some anionic dyes (i.e., methyl orange, methyl red, and Congo red), there was an enhancement in crystal violet (a cationic dye) adsorption after incorporation of humic acid. The Langmuir model fitted well to crystal violet data, and monolayer adsorption capacity was calculated as 81.6 mg/g (r(2) = 0.998).Öğe Investigating sorption characteristics of copper ions onto insolubilized humic acid by using a continuously monitored solid phase extraction technique(ELSEVIER SCIENCE BV, 2007) Gezici, Orhan; Kara, Huseyin; Yanik, Sema; Ayyildiz, H. Filiz; Kucukkolbasi, SemahatThe sorption characteristics of Cu(II) in an insolubilized humic acid (IHA) mediated column system were investigated at various experimental conditions using a solid phase extraction (SPE) technique. Sodium form of the IHA (INaA) was used as solid phase and sorption behaviors were evaluated by using common adsorption isotherms as well as Scatchard plot analysis. Regeneration, loading, washing and stripping steps of SPE were carried out consecutively, and their progresses were monitored through breakthrough curves obtained from a continuous flow-through cell adapted UV-vis spectrophotometer. So, the breakthrough curves were used to visualize distribution of Cu(II) concentration between mobile phase and solid phase, and amount of the Cu(II) sorbed by INaA was obtained from AAS analysis of effluents collected during the stripping steps of particular run. Thus, from the obtained results, the sorption characteristics and usability of IHA as a solid phase for SPE of metal ions was evaluated in detail. (c) 2007 Elsevier B.V. All rights reserved.Öğe Modelling the kinetics of direct Cu(II) adsorption on two porous resins modified with mussel-inspired chemistry(Springer, 2022) Bisgin, Abdullah Taner; Gezici, OrhanTwo synthetic resins (i.e. Dowex Optipore V493 (DOV493) and XAD7) were subjected to a physical surface modification with mussel-inspired chemistry. Kinetics of direct Cu(II) adsorption were studied and the experimental data were modeled according to some adsorption kinetic models. The studied kinetic models suggested (i) diffusion-controlled and (ii) adsorption-controlled mechanisms for the direct adsorption of Cu(II) on PD-DOV493 and PD-XAD7, respectively. Regardless of the rate-limiting step, the studied two polymeric resins (i.e. DOV493 and XAD7) could be converted to new forms capable of binding Cu(II), which in their original form is impossible. Equilibrium adsorption capacities around 70 mu g/g and 500 mu g/g were determined to be accessible for PD-DOV493 and PD-XAD7, respectively, at relatively low initial Cu(II) concentrations (i.e. similar to 1-3 ppm). It is believed that the obtained results will be useful for understanding the nature of heavy metal adsorption kinetics on PD-coated porous polymeric resins.Öğe Novel humic acid-bonded magnetite nanoparticles for protein immobilization(ELSEVIER SCIENCE BV, 2014) Bayrakci, Mevlut; Gezici, Orhan; Bas, San Zeki; Ozmen, Mustafa; Maltas, EsraThe present paper is the first report that introduces (i) a useful methodology for chemical immobilization of humic acid (HA) to aminopropyltriethoxysilane-functionalized magnetite iron oxide nanoparticles (APS-MNPs) and (ii) human serum albumin (HSA) binding to the obtained material (HA-APS-MNPs). The newly prepared magnetite nanoparticle was characterized by using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and elemental analysis. Results indicated that surface modification of the bare magnetite nanoparticles (MNPs) with aminopropyltriethoxysilane (APS) and HA was successfully performed. The protein binding studies that were evaluated in batch mode exhibited that HA-APS-MNPs could be efficiently used as a substrate for the binding of HSA from aqueous solutions. Usually, recovery values higher than 90% were found to be feasible by HA-APS-MNPs, while that value was around 2% and 70% in the cases of MNPs and APS-MNPs, respectively. Hence, the capacity of MNPs was found to be significantly improved by immobilization of HA. Furthermore, thermal degradation of HA-APS-MNPs and HSA bonded HA-APS-MNPs was evaluated in terms of the Horowitz-Metzger equation in order to determine kinetic parameters for thermal decomposition. Activation energies calculated for HA-APS-MNPs (20.74 kJ mol(-1)) and HSA bonded HA-APS-MNPs (33.42 kJ mol(-1)) implied chemical immobilization of HA to APS-MNPs, and tight interactions between HA and HA-APS-MNPs. (C) 2014 Elsevier B.V. All rights reserved.Öğe On the removal of some phenolic compounds from aqueous solutions by using a sporopollenin-based ligand-exchange fixed bed - Isotherm analysis(ELSEVIER SCIENCE BV, 2008) Ayar, Ahmet; Gursal, Selpic; Gurten, A. Ali; Gezici, OrhanSingle component adsorption of phenol and 2-, 3- and 4-nitrophenol from water was studied under dynamic column conditions by using a carboxymethyl diaminoethane sporopollenin in a cobalt ion-loaded form, Co(II)-CDAE-S, as solid phase. Adsorption isotherm data were acquired by frontal analysis for five plateau concentrations ranged from 1.25 x 10(-5) to 2.00x 10(-4) mol l(-1). The studied ligand-exchange sporopollenin resin showed a selective adsorptive nature within the group of studied nitrophenols, and the nature of phenols' adsorption on the Co(II)-CDAE-S was analyzed in terms of specific bindings by using Scatchard plot analysis. In light of the Scatchard plot analysis, the adsorption of examined compounds was mainly attributed to the specific bindings based on the ligand-exchange matrix of the studied adsorbent. The nitro-substituted phenols were found to be less strongly adsorbed than the phenol, and both binding strength and theoretical saturation capacity had an obvious relationship with the position of nitro substituent: The theoretical saturation capacities calculated from applied isotherm models exhibited an increase in the order of phenol < 4-nitrophenol < 3-nitrophenol < 2-nitrophenol, whereas a reverse order was showed for binding strengths.Öğe Protein İyon-Değişim Kromatografisi İçin Kaliksaren-Kriyojel Esaslı Yeni Tip Monolitik Kolonların Sentezlenmesi(2017) Gezici, Orhan; Morbıdellı, Massimo; Bayrakcı, MevlütSunulan bu çalışmada; sülfonat, fosfonat ve karboksilat grupları içeren bazı kaliks[4]arenlerin (tetrafosfonato kaliks[4]aren, P-CLX-PO4, tetrasülfonato kaliks[4]aren, PCLX-SO3, ve tetrakarboksilato kaliks[4]aren, P-CLX-COOH) kriyojel esaslı monolitik destek katısına immobilizasyonu ve elde edilen sabit fazların protein iyon değişim kromatografisinde kullanılabilirlikleri incelenmiştir. İmmobilizasyon işleminde destek katısı olarak poly(2hidroksietilmetakrilat)-co-glisidilmetakrilat (P) kullanılmış ve yapısındaki epoksit grupları üzerinden kaliksaren immobilizasyonu gerçekleştirilmiştir. Elemental analiz, FTIR, SEM, izoelektrik nokta tayini, cıva porozimetresi ve titrimetrik analiz gibi yöntem ve teknikler kullanılarak sabit fazlar karakterize edilmiştir. P-CLX-PO4, P-CLX-SO3 ve P-CLX-COOH için yüzeye immobilize edilmiş kaliksaren miktarı sabit fazın gramı başına sırasıyla 173 mg/g, 125 mg/g ve 210 mg/g olarak hesaplanmıştır. Kromatografik deneyler hem lineer hem de lineer olmayan kromatografik şartlarda yürütülmüş ve böylece ayırma verimliliği ve protein adsorpsiyon kapasitesi gibi özellikler incelenmiştir. P-CLX-PO4, P-CLX-SO3 ve P-CLXCOOH için toplam dinamik adsorpsiyon kapasiteleri sırasıyla 7,7 mg/mL, 5,9 mg/mL ve 2,9 mg/mL olarak bulunmuştur. İyon-değişim mekanizmasının rolünü irdeleyebilmek amacıyla kromatografik veriler Yamamoto Modeli temelinde analiz edilmiş ve iyon-değişimin baskın mekanizma olduğu tespit edilmiştir. Destek katısına immobilize edilen kaliksaren molekülündeki fonksiyonel grubun türüne bağlı olarak alıkonma özelliklerinde önemli farklılaşmaların meydana geldiği anlaşılmıştır. Çalışılan 3 farklı sabit faz arasında en iyi verim P-CLX-PO4 ve P-CLX-SO3 ile elde edilmiş, P-CLX-COOH sabit fazının hem ayırma verimliliği hem de adsorpsiyon kapasitesi bakımından daha düşük performans sergilediği görülmüştür. Bu durum, sabit fazların zayıf ve kuvvetli katyon değiştirici özellikleri ile ilişkilendirilmiştir. Bazı model proteinlerin, özellikle P-CLX-PO4 sabit fazı üzerinde, kromatografik ayrılmaları başarılı bir şekilde gerçekleştirilmiştir. Supramoleküler kimyanın önemli üyelerinden olan kaliksaren kimyasının kriyojel kimyası ile ilk defa birleştirildiği bu çalışma, protein iyon-değişim kromatografisi için yeni tip sabit fazların tasarlanması noktasında yenilikçi yaklaşımlar sunmuştur.Öğe Simultaneous Preconcentration and Spectrophotometric Determination of Two Colorants (E110 and E133) in Some Foodstuffs Using a New Mussel-Inspired Adsorbent(Oxford Univ Press Inc, 2021) Bisgin, Abdullah Taner; Nalvuran, Zeynep; Gezici, OrhanBackground: A naturally occurring material, namely sporopollenin (SP), was subjected to an easy physical surface modification process called a polydopamine coating. The treatment changed the acid-base properties of the surface, so that in the new form the SP surface gained a very attractive character for anionic dyes. Objective: The aim of the study was to develop preconcentration and subsequent spectrophotometric determination methods for two anionic colorants, brilliant blue (BB) and sunset yellow (SY), using polydopamine-coated (PDC) SP. Method: The experiments were carried out in a column system, and the effects of experimental parameters were studied to determine optimal conditions for the quantitative, simultaneous spectrophotometric determination of the dyes. Results: The dyes could be detected at mu g/L levels in their binary mixtures, so the detection limits were found to be 1.5 and 4.3 mu g/L in the linear dynamic ranges of 0.0-3.5 and 0-8 mu g/mL for BB and SY, respectively. The proposed material and procedure led to quantitative recoveries of between 95 and 100% for the dyes. Conclusions: The procedure was applied to real food samples containing BB and SY and both dyes were successfully determined in liquid and solid foodstuffs. The mussel-inspired surface modification is proposed as a useful process to modify the surface of SP. Highlights: The mussel-inspired polydopamine dip-coating method was adopted to modify the surface of SP for the first time. The PDCSP was successfully used to create a new adsorptive preconcentration method for simultaneous spectrophotometric determination of BB and SY in foodstuffs.Öğe Sorption behavior of Cu(II) ions on insolubilized humic acid under acidic conditions: An application of Scatchard plot analysis in evaluating the pH dependence of specific and nonspecific bindings(ELSEVIER SCIENCE BV, 2007) Gezici, Orhan; Kara, Huseyin; Ayar, Ahmet; Topkafa, MustafaSorption behavior of Cu(II) ions on a humic acid-based solid phase, insolubilized humic acid (IHA), were investigated under continuous column conditions. The quantitative data were derived on the basis of breakthrough curves obtained at different experimental conditions. For the studied experimental conditions, the highest and lowest observable capacities of IHA toward Cu(II) were found as 48.34 and 0.84 mu mol g(-1), respectively. In order to evaluate the pH dependence of Cu(II) binding on IHA, the effect of influent concentration was investigated at three different pH values (1.0, 2.0 and 3.0), and adsorption isotherms were derived for each acidic condition. The characteristics of Cu(II) bindings were evaluated by using Scatchard plot analysis, and it was observed that under strongly acidic condition, pH 1.0, nonspecific and/or multi-type interactions between Cu(II) and MA were the prevailing effects causing the Cu(II) sorption. On the other hand, at pH 2.0 and 3.0, the role of specific interactions was more clearly observed, and so at pH(s) 2.0 and 3.0, the binding of Cu(II) on IHA was mainly attributed to specific interactions rather than nonspecific ones. For pH 2.0 and 3.0, the binding types of Cu(II) on IHA were sub-classified according to different affinities observed between Cu(II) and IHA, and thus two main types of specific bindings were proposed for the studied influent concentration range (1.0 x 10(-3) to 1.0 X 10(-1) mol l(-1)): Type-1, high-affinity/low capacity and Type-2, low-affinity/high capacity bindings. Finally, probable benefit of each specific binding type in separation of Cu(II) from acidic aqueous media has been discussed in detail. (c) 2006 Elsevier B.V. All rights reserved.Öğe Sporopollenin destek katısının katı faz ekstraksiyonu ve sıvı kromatografisi sistemlerinde kullanılabilirliğinin araştırılması(2009) Ayar, Ahmet; Gezici, Orhan[Abstract Not Available]Öğe Stepwise Frontal Analysis to Derive Equilibrium Sorption Data for Copper and Aniline on Functionalized Sporopollenin(WILEY-BLACKWELL, 2009) Gezici, Orhan; Ayar, AhmetA dynamic method called stepwise frontal analysis (SFA) was Used to derive equilibrium sorption data of copper and aniline on a carboxylated diaminoethane sporopollenin (CDAE-S) solid phase. The derived data wits modeled on the basis of some common adsorption isotherms, and the importance of Scatchard plot analysis in isotherm modeling was emphasized. In light of the applied isotherm models, the role of aminocarboxylic acid functionalities in the sorption of each chemical species was discussed in terms of specific and nonspecific binding.Öğe Strong cation-exchange chromatography of proteins on a sulfoalkylated monolithic cryogel(ELSEVIER SCIENCE BV, 2015) Percin, Isik; Khalaf, Rushd; Brand, Bastian; Morbidelli, Massimo; Gezici, OrhanA new strong cation exchanger (SCX) monolithic column was synthesized by at-line surface modification of a cryogel prepared by copolymerization of 2-hydroxyethylmethacrylate (HEMA) and glycidyl-methacrylate (GMA). Sodium salt of 3-Mercaptopropane sulfonic acid (3-MPS) was used as the ligand to transform the surface of the monolith into a strong cation exchanger. The obtained material was characterized in terms of elemental analysis, infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) N-2 adsorption, and used as a stationary phase for strong-cation exchange chromatography of some proteins, such as a-chymotrypsinogen, cytochrome c and lysozyme. Water permeability of the column was calculated according to Darcy's law (2.66 x 10(-13) m(2)). The performance of the monolithic cryogel column was evaluated on the basis of Height Equivalent to a Theoretical Plate (HETP). Retention behavior of the studied proteins was modeled on the basis of Yamamoto model to understand the role of the ion-exchange mechanism in retention behaviors. The considered proteins were successfully separated, and the obtained chromatogram was compared with that obtained with a non-functionalized cryogel column. (c) 2015 Elsevier B.V. All rights reserved.Öğe Subtractive-FTIR spectroscopy to characterize organic matter in lignite samples from different depths(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Gezici, Orhan; Demir, Ibrahim; Demircan, Aydin; Unlu, Nuri; Karaarslan, MuhsinOrganic matter present in lignite samples collected from different depths (i.e. top, mid and bottom) of lignite source. Ilgin, Konya province, was examined by using subtractive-FTIR-ATR spectroscopy. FTIR spectra were recorded on (i) original samples, (ii) the samples dried at 105 degrees C and (iii) the samples acid-treated and dried. After a combustion process performed for each sample at 650 degrees C for 15 min, the spectra of samples were recorded and subtracted from the spectra of untreated samples. Hence, a software-based subtraction made it possible to acquire a representative spectra related with organic matter. As the contribution of the bands related with inorganic constituents in lignite samples were eliminated after spectrum-subtraction procedure, difference-spectra led analyzing the spectra related with organic matter in lignite samples, reasonably. Furthermore, the bands related with acidic functional groups, aromatic and aliphatic structures were analyzed on the basis of difference-spectra, easily. From the difference-spectra it was shown that an acid-treatment process under mild conditions caused shift in some specific bands related with carbonyl groups of carboxyls so that the band at around 1710 cm(-1) arisen, while the intensity of the band at around 1420 cm(-1) was diminished. Through the acid-treatment process, acidic groups in lignite samples from different depths were thought to be turned into similar forms by protonation and/or stripping of metal ions originally bonded. Difference-spectra acquired for acid-treated samples made it possible to evaluate the form of carboxylic acid groups present in the studied samples under specific environmental conditions. Hence, a facile and environmentally-friendly methodology was used to analyze organic matter in lignite by using FTIR spectra, and valuable information was acquired about the aliphatic, aromatic and acidic character of the studied lignite samples collected from different depths. The proposed methodology seems to be promising in acquiring approximate representative spectra for lignite organic matter by using little or no chemicals. (C) 2012 Elsevier B.V. All rights reserved.
