Ebru Birlik Özkütük

Preconcentration of phosphate ion onto ion-imprinted polymer.

In this study, selective separation and preconcentration of phosphate ions on the phosphate-imprinted chitosan-succinate beads have investigated. Chitosan-succinate, phosphate, epichlorohydrin were used as the complexing monomer, template and crosslinking agent, respectively. In the first step, chitosan was modified with succinic anhydrides and complex formation occurred between carboxylic acid functional groups and iron(III) ions. Secondly, Fe(III)-chitosan-succinate particles were reacted with phosphate ions. Afterwards, particles were crosslinked with epichlorohydrin and the template (phosphate ions) was removed using 1M KOH solution. Selective cavity for the phosphate ion was obtained in the phosphate-imprinted metal-chelate polymer. These phosphate-imprinted metal-chelate polymer was used in the adsorption-desorption process. The adsorption process was fast and equilibrium was reached around 30 min. The adsorption behaviour of this system was described approximately by the Langmuir equation. Percent extraction, distribution ratio and selectivity coefficients of phosphate and other ions using non-imprinted and phosphate-imprinted polymer were also determined and comparison of these data was reported.

Ligand exchange based paraoxon imprınted QCM sensor.

In the present work, a paraoxon imprinted QCM sensor has been developed for the determination of paraoxon based on the modification of paraoxon imprinted film onto a quartz crystal combining the advantages of high selectivity of the piezoelectric microgravimetry using MIP film technique and high sensitivity of QCM detection. The paraoxon selective memories have formed on QCM electrode surface by using a new metal-chelate interaction based on pre-organized monomer and the paraoxon recognition activity of these molecular memories was investigated. Molecular imprinted polymer (MIP) film for the detection of paraoxon was developed and the analytical performance of paraoxon imprinted sensor was studied. The molecular imprinted polymer were characterized by FTIR measurements. Paraoxon imprinted sensor was characterized with AFM and ellipsometer. The study also includes the measurement of binding interaction of paraoxon imprinted quartz crystal microbalance (QCM) sensor, selectivity experiments and analytical performance of QCM electrode. The detection limit and the affinity constant (K(affinity)) were found to be 0.06 μM and 2.25 × 10(4) M(-1) for paraoxon [MAAP-Cu(II)-paraoxon] based thin film, respectively. Also, it has been observed that the selectivity of the prepared paraoxon imprinted sensor is high compared to a similar chemical structure which is parathion.

Determination of Clenbuterol by Multiwalled Carbon Nanotube Potentiometric Sensors

ABSTRACT Potentimetric sensors based on molecularly imprinted polymers are reported for the selective determination of clenbuterol. The work involved the modification of multiwalled carbon nanotubes, the modification of chitosan with diethylene triamine pentaacetic acid, the synthesis of the clenbuterol-imprinted polymer, and the preparation of potentiometric sensors using the clenbuterol-imprinted polymer. The effect of pH, response time, lifetime, selectivity, reusability, reproducibility, accuracy, and stability of the sensors were characterized. The optimum pH was 6.0 for the prepared poly(vinyl chloride) membrane and carbon paste electrodes. The limit of detection of the poly(vinyl chloride) membrane electrode was 0.49 × 10−8 mM, with the linear dynamic range from 1.0 × 10−5 to 1.0 × 10−9 mM. The response time for the membrane electrode was 2 min and the operational lifetime was 23 weeks. For the carbon paste electrode, the limit of detection was 0.91 × 10−8 mM, the linear dynamic range was from 1.0 × 10−4 to 1.0 × 10−9 mM, the response time was 1 min, and the operational lifetime was 24 weeks.

Development of New Molecular Imprinted Solid Phase Extraction Material for Dimethoate

ABSTRACT In this study, we have proposed a novel organophosphate mimic surface molecular imprinted polymer for selective binding of the nerve agent by chitosan–Cd(II) as a new metal-chelating monomer via metal coordination–chelation interactions and dimethoate templates. We have improved a method for the selective binding behavior of dimethoate compounds on the surface of molecular imprinted polymer, which was prepared using ligand-exchange (chitosan–Cd(II)) monomers. The influence of ligand exchange imprinting on the creation of recognition sites toward dimethoate has determined application of adsorption isotherms. The effect of initial concentration of dimethoate, adsorption time, and imprinting efficiency on the adsorption selectivity for molecular imprinted polymer-ligand exchange has been investigated. The number of accessible sites (Qmax), relative selectivity coefficients (k′), and binding abilities have also been evaluated. Then, molecular imprinted polymer-ligand exchange was treated with formaldehyde to remove dimethoate templates.

Potentiometric sensor fabrication having 2D sarcosine memories and analytical features

In this study, a simple, rapid and sensitive method based on novel molecular imprinted polymeric sensor has been developed and validated for the determination of prostate cancer metabolite biomarker. The molecularly imprinted polymer (MIP) has been synthesized by emulsion polymerization, using sarcosine as template molecule, methacryloylamido histidine (MAH) as functional monomer and ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The performance of the developed sarcosine sensor has been evaluated, and the results have indicated that a sensitive potentiometric sensor has been fabricated. The sarcosine sensor has showed high-selectivity, shorter response time (<2min), wider linear range (10(-2)-10(-6)mM), lower detection limit (1.35×10(-7)mM), and satisfactory long-term stability (>5.5months).

Double-imprinted potentiometric sensors based on ligand exchange for the determination of dimethoate

This paper describes a dimethoate imprinted polymeric potentiometric sensor for the determination of dimethoate that was designed by dispersing the dimethoate-imprinted polymer in dibutyl phthalate plasticizer and then embedded in polyvinyl chloride matrix. The method is based on molecularly imprinted polymer (MIP), which can be synthesized by using dimethoate as a template molecule, chitosan-Cd(II), and 3-mercaptopropyl-trimethoxysilane as a functional monomer and TEOS, and ephychlorohydrin as a cross-linking agent. We have studied a method for the selective binding behavior of dimethoate compounds on the surface of imprinted polymers which is prepared using ligand-exchange (LE) (chitosan-Cd(II)) monomer. The MIP-LE-1 and MIP-LE-2 based membranes have shown a detection limit of 4.3×10−6 mmolL−1 and 3.5.10−5 mmolL−1, respectively. The sensor has exhibited a response time of 35min for MIP-LE-1 and 120min for MIP-LE-2. They are stable for more than three months.

Biopolymer based ion imprinting cryogel traps for the removal of Tl(I)

ABSTRACT The aim of this study is to prepare supermacroporous cryogel with embedded ion imprinted polymer (IIP) particles which can be used for the selective removal of Tl(I) from aqueous solution. In the first step, Tl(I) has complexed with chitosan and crosslinked with ephychlorohydrin. In the second step, the supermacroporous poly(hydroxyethyl methacrylate) (PHEMA) cryogel with embedded IIP particles [PHEMA/MIP composite cryogel] which have been produced by free radical polymerization initiated by N,N,N’,N’-tetramethylene diamine (TEMED) and ammonium persulfate (APS) pair in ice bath. The template, Tl(I), has been removed from the polymer using 0.1 M EDTA solution. The cryogel is characterized by swelling test, scanning electron microscopy, and Fourier transform infrared spectroscopy. The effective parameters on Tl(I) adsorption process have evaluated by investigating the dependency of the adsorption capacity on flow-rate, Tl(I) concentration and contact time. The maximum adsorption capacity of Tl(I) ions has been found to be 1.55 µgg−1. The selectivity of the IIP biopolymer cryogel has investigated by competitive adsorption of Cd(II), Cu(II), K(I), and Fe(II). The relative selectivity coefficients of IIP biopolymer cryogel are 3.98 and 62.5 for Cd(II) and Cu(II), respectively. The IIP biopolymer cryogel could be used many times without any significant decrease in the adsorption capacity. As a conclusion it can be said that the IIP biopolymer cryogel could be used for specific separation of Tl(I) ions from nuclear, industrial, and environmental waste.

Synergistic thallium and iodine memory-based cryogel traps for removing thallium and iodine ions

Both recovery and effective removing of radioactive thallium and iodine are important subject to protect human health and the environment. In this study, we have studied synergistic and cost-effective cryogel based sorbents by combining the high selectivity adsorption ability of MIP and the high porosity of cryogels. For thallium-imprinted cryogel; N-methacryloyl-(l)-cysteine (MAC) has synthesized, MAC has complexed with thallium ion and polymer cryogel has been prepared. For iodine-imprinted cryogel; MAC-thallium has complexed with iodine; and polymer cryogel has been prepared. Then, the adsorption, desorption, selectivity and reusability experiments have been carried out.

SELECTIVE REMOVAL OF Cd(II) USING DOUBLE IMPRINTED POLYMER FROM SYNTHETIC WATER

Bu calismanin amaci, sentetik sudan Cd(II)’nin secici uzaklastirilmasi icin kullanilabilecek iyon baskili polimer hazirlamaktir. Iyon baskili polimer partikulleri, dodesilamin ve Cd(II) varliginda, capraz baglayici olarak teraetoksisilan, monomer olarak 3-merkaptopropil-trimetoksilanin kullanildigi molekuler baskilama teknigi ile hazirlanmistir. Daha sonra baski iyonlari 0,1 M HNO3/etanol kullanilarak uzaklastirilmistir. Bec islemi, Cd(II) kati faz ozelliklerinin belirlenmesi icin kullanilmistir. Elde edilen sonuclar, iyon baskili polimerin buyuk adsorpsiyon kapasitesine (98.2 mgg-1) sahip oldugunu gostermistir. Optimum pH ve adsorpsiyon suresi sirasiyla 5.0 ve 2 saat olarak bulunmustur. Secicilik calismalarinda, baskilama ayni yuklu diger yarismaci metal iyonlari uzerinden Cd(II) iyonlarina dogru materyalin afinitesinin arttigi bulunmustur. Cd(II)/Zn(II), Cd(II)/Cu(II) and Cd(II)/Hg(II)’in secicilikleri sirasiyla 2,73; 8,83 ve 112 olarak bulunmustur