Investigation of adsorption properties of spider silk and its usage in preconcentration of some metal ions

Bu çalışmanın ana hedefi örümcek ağının bir kolon maddesi olarak metal iyonlarına karşı kullanım koşullarını incelemektir. Örümcek ağları 1:1 HCl çözeltileri ile işlem gördükten sonra boyutu küçültülerek, PVC destek ile doldurulmuş kolona yerleştirilmiş ve metal iyonlarının akışkan sistemde etkileşimleri incelenmiştir. Örümcek ağının adsorban özellikleri adsorpsiyon ve elusyon aşamalarında metal iyon derişimleri ICP-MS ve FAAS sistemleri ile ölçülerek incelenmiştir. Adsorpsiyon kapasiteleri Cu(II) ve Pb(II) iyonları için 8.22 mg/g (1.3x10-4 mol/g) ve 15.78 mg/g a% (7.6x10-5 mol/g) olarak hesaplanmıştır. Bu rakamlar literatürde verilen diğer biyomateryallerle kıyaslanabilir düzeyde bulunduğundan, örümcek ağı yeni ve orijinal bir adsorban olarak ümit vadetmektedir. Hat-üstü amperometric ölçümlerde Cu(II) ve Pb(II) iyonlarının adsorpsiyon koşullarının optimizasyonu üzerinde durulmuş ve ortam pH’ı, tampon türü ve derişimi, akış hızı ve elektrot potansiyelinin etkisi incelenmiştir. En uygun koşullar altında belirtme sınırı Cu(II) ve Pb(II) için 70 ng/mL ve 35 ng/mL olarak hesaplanmıştır. Ancak, her iki iyon birarada iken sinyal çakışması gözlenmesi nedeniyle seçimliliğin artırılması gerekmektedir. Bu nedenle amperometrik piklerin oluşumuna yakın akış durdurularak, ardışık alınan kare dalga voltammogramlar yardımıyla bu iki iyon birbiri yanında gözlenebilmiştir. Bu yolla iyi ayrılmış ve daha iyi sinyal/gürültü oranına sahip pikler elde edilebilmiştir

Determination of mercury bu using dithizone loaded amberlite XAD-7 resin modified carbon paste electrode

Civa(II) nin kimyasal yolla saptanması uzun yıllardır uygulanmaktadır. XAD-7 ağır metalleri adsorplama özelliğine sahiptir fakat Hg(II) için seçimli değildir ve Hg(II) için seçimli olan ditizon la yüklenebilir. İlk olarak, ditizon XAD-7 reçinesine yüklendi ve adsorpsiyon kapasitesi ile hangi tür bağlanmanın olduğu araştırıldı. Daha sonra bu elektrot modifiye karbon pasta elektrodunda modifiye madde olarak kullanıldı ve voltammetrik davranışları incelendi. Bunun için optimum koşullar saptandı. Daha sonra girişimci etkiler incelendi. Sonra bu elektrot XAD-7 modifiye karbon pasta elektrodu ve karbon pasta elektrodu ile optimum koşullarda karşılaştırıldı. Son olarak medium exchange koşullarda kalibrasyon grafiği oluşturuldu ve kalibrasyon grafiğinin regrasyon katsayısı 0.988 olarak bulundu. Ditizon yüklenmiş XAD-7 modifiye karbon pasta elektrodunun belirtme alt sınırı 2x10-7 M civa(II) ve bağıl standart sapma ±6% olarak bulundu

Sensitive determination of hydrogen peroxide in real water samples by high spin peroxo complex

In this paper, a fast, cheap, simple, sensitive and selective spectrophotometric method based on high spin peroxo-Fe(III)-EDTA complex in the alkaline medium was developed for the determination of hydrogen peroxide (H2 O2) in real water samples. the purple-coloured complex with a maximum absorbance at a wavelength of 525 nm was formed. Various parameters such as type of stabilizer reagent and its concentration, reaction time, Fe(III), EDTA and NH3 concentration were optimized. the method was confirmed with the Beer’s law with a molar absorption coefficient of 267.36 L mol ?1 cm ?1 in the 8.3 ×10 ?6 –4.08 ×10 ?3 mol/L concentration range. Sandell’s sensitivity of the proposed method was also calculated as 0.188 µg/cm2 . LOD and LOQ were determined as 2.5 ×10 ?6 and 8.3 ×10 ?6 mol/L, respectively. Intraday and interday relative standard deviation of the proposed method for 2.0 ×10 ?4 mol / L of H2 O2 were found as 1.5% and 6.1%, respectively. the developed method is suitable for fast monitoring of H2 O2 in different types of aqueous water samples without any sample preparation steps and acceptable recovery values between 90% and 118% were obtained. in the sample analysis, H2 O2 removed solutions from the real water samples were used for blank correction in their analysis and this process provides more reliable and accurate results in real sample analysis

Electrochemically Fabricated Solid Phase Microextraction Fibers and their Applications in Food, Environmental and Clinical Analysis

Pelit, Levent/0000-0001-8090-703X; Pelit, Fusun/0000-0003-0551-664XWOS: 000494943600003Background: Designing an analytical methodology for complicated matrices, such as biological and environmental samples, is difficult since the sample preparation procedure is the most demanding step affecting the whole analytical process. Nowadays, this step has become more challenging by the legislations and environmental concerns since it is a prerequisite to eliminate or minimize the use of hazardous substances in traditional procedures by replacing with green techniques suitable for the sample matrix. Methods: in addition to the matrix, the nature of the analyte also influence the ease of creating green analytical techniques. Recent developments in the chemical analysis provide us new methodologies introducing microextraction techniques and among them, solid phase microextraction (SPME) has emerged as a simple, fast, low cost, reliable and portable sample preparation technique that minimizes solvent consumption. Results: the use of home-made fibers is popular in the last two decades since the selectivity can be tuned by changing the surface characteristics through chemical and electrochemical modifications. Latter technique is preferred since the electroactive polymers can be coated onto the fiber under controlled electrochemical conditions and the film thicknesses can be adjusted by simply changing the deposition parameters. Thermal resistance and mechanical strength can be readily increased by incorporating different dopant ions into the polymeric structure and selectivity can be tuned by inserting functional groups and nanostructures. A vast number of analytes with wide range of polarities extracted by this means can be determined with a suitable chromatographic detector coupled to the system. Therefore, the main task is to improve the physicochemical properties of the fiber along with the extraction efficiency and selectivity towards the various analytes by adjusting the electrochemical preparation conditions. Conclusion: This review covers the fine tuning conditions practiced in electrochemical preparation of SPME fibers and in-tube systems and their applications in environmental, food and clinical analysis

Preparation and application of a polythiophene solid-phase microextraction fiber for the determination of endocrine-disruptor pesticides in well waters

WOS: 000325139700013PubMed ID: 23913719A robust solid-phase microextraction fiber was fabricated by electropolymerization of thiophene on a stainless steel wire. This fiber was applied for the determination of endocrine-disruptor pesticides, namely, chlorpyrifos, penconazole, procymidone, bromopropylate, and -cyhalothrin in well waters by a headspace solid-phase microextraction procedure. Operational parameters, namely, pH, sample volume, adsorption temperature and time, desorption temperature, stirring rate, and salt amount were optimized as 7.0, 8 mL, 70 degrees C and 20 min, 250 degrees C, 600 rpm, and 0.3 g/mL, respectively. The separation power of GC was coupled with the excellent sensitivity of the developed fiber enabling us to determine pesticide mixtures simultaneously in a ng/mL range. The LOD was in the range of 0.02-0.64 ng/mL. The method was successfully applied for the selective and sensitive determination of target pesticides in well water samples with acceptable recovery values (92-110%). The polythiophene fiber gives satisfactory results compared with commercial fibers. Commonly used pesticides with different polarities were chosen as representative compounds to search the applicability of the fiber for well water analysis collected from vineyards.Ege UniversityEge UniversityThe authors thank the Ege University for financial support and TUBITAK (2209)

Water-soluble cis-[(NHC)PdBr2(TPPTS)] catalysts and their applications in Suzuki-Miyaura coupling of aryl chlorides

WOS: 000296038500011New palladium(II) complexes (2), bearing NHC/TPPTS ligands, (NHC = benzimidazol-2-ylidene; TPPTS = triphenylphosphine-3,3',3 ''-trisulfonic acid trisodium salt) have been prepared and characterized by elemental analyses and spectroscopic methods. Their ability to catalyze the Suzuki-Miyaura reaction in neat water has been studied at 100 degrees C. Very high activities have been observed in the coupling of phenylboronic acid with aryl chlorides in the presence of 1% of the catalyst. We have compared the electronic properties of cis-[PdBr2(NHC)(TPPTS)] with the related complexes, [PdX2(NHC)](2) and [trans-PdBr2(NHC)(pdca)](Pdca = pyridine-2,6-dicarboxyic acid) (3) via three different techniques: cyclic voltammetry, thermogravimetric analysis and C-13 NMR spectroscopy. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.Ege UniversityEge University [2010-FEN-046, 2010-Fen- 076]; Turkish Academy of Sciences (TUBA)Turkish Academy of SciencesFinancial support from Ege University (Project 2010-FEN-046 and 2010-Fen- 076) and The Turkish Academy of Sciences (TUBA) is gratefully acknowledged. We also thank to Dr. S. Astley at Ege University Chemistry Department for the manuscript reading

A spectrophotometric method for determination of molybdenum in water samples by using pyrogallol red and a water soluble ionic liquid

WOS: 000324927300061The present study describes a simple and sensitive spectrophotometric method for the determination of molybdenum in real water samples. The method is based on the hyperchromic and bathochromic effect of an ionic liquid namely, 1-methyl-3-octadecyl-imidazolium bromide (C(18)mimBr), on molybdenum ion (Mo(VI)) and pyrogallol red (PGR) complex. The ternary complex of Mo-PGR-C(18)mimBr displays a distinct absorption peak with excellent analytical characteristics and offers the advantages of simplicity for the determination of Mo(VI) ions, without any need for a solvent extraction step. The limit of detection (LOD) and limit of quantification (LOQ) of the method were calculated as 0.74 ng mL(-1) and 2.47 ng mL(-1) respectively. The method was validated and applied successfully to the determination of Mo(VI) ions in real water samples. The interference of ferric ions was shown to be removed from samples with less ionic content by using an ion exchange resin prior to the analysis, and the performance of the method was compared with that of ICP-MS.Ege UniversityEge UniversityAuthors thank Ege University for financial support and Ege University, Centre for R&D and Pharmacokinetic Applications Environmental & Food Analysis Laboratory (ARGEFAR) for ICP-MS measurements. Authors would like to thank Ass. Prof. Armagan Kinal for proof reading

Adsorptive Cathodic Stripping Voltammetric Determination of Boscalid in the Presence of Cobalt Ions at a Pencil Lead Electrode

WOS: 000416519900016Here is described a novel voltammetric method for boscalid. Boscalid is a broad-spectrum fungicide known to be electrochemically inactive. However, it forms complexes with cobalt(II) through its pyridine carboxamide group that allows its indirect determination by adsorptive cathodic stripping voltammetry after deposition at positive potentials. The catalytic character of the reduction peak at -1.2 V was established by the mechanistic studies. After optimization of the parameters, calibration relationships were obtained at nanomolar concentrations and the method was used to analyze tomato juice and tomato paste with satisfactory recoveries.Turkish Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114Z394]; Ege University Research Fund projects [2015 FEN 033]The authors would like to thank the Turkish Scientific and Technological Research Council of Turkey (TUBITAK) (Project no: 114Z394) and Ege University Research Fund projects (2015 FEN 033)