Mustafa Gülfen

Synthesis of a novel dithiooxamide–formaldehyde resin and its application to the adsorption and separation of silver ions

In this study, a new chelating resin of dithiooxamide (rubeanic acid)-formaldehyde (DTOF) has been synthesized by the reaction of dithiooxamide and formaldehyde. Also a well-known chelating resin of thiourea (thiooxamide)-formaldehyde (TUF) has been prepared by the reaction of thiourea and formaldehyde. DTOF and TUF chelating resins were used in the adsorption, separation and concentration of silver ions by batch and column techniques. These resins were characterized using FTIR and elemental analysis. It was found that DTOF resin has silver adsorption capacity of 3333.3 mg g(-1) or 30.86 mmolg g(-1) and TUF resin has the capacity of 1428.6 mg g(-1) or 13.22 mmol g(-1). DTOF resin showed more affinity to silver ions according to Cu(II), Zn(II), Ni(II) and Co(II) base metal ions than TUF resin. It was also demonstrated that DTOF resin can be used in the separation and concentration of silver ions.

Separation and Recovery of Silver(I) Ions from Base Metal Ions by Melamine‐formaldehyde‐thiourea (MFT) Chelating Resin

Abstract Melamine‐formaldehyde‐thiourea (MFT) chelating resin were prepared using melamine (2,4,6‐triamino‐1,3,5‐triazine), formaldehyde, and thiourea and this resin has been used for separation and recovery of silver(I) ions from copper(II) and zinc(II) base metals and calcium(II) alkaline‐earth metal in aqueous solution. The MFT chelating resin was characterized by elemental analysis and FT‐IR spectra. The effect of pH, adsorption capacity, and equilibrium time by batch method and adsorption, elution, flow rate, column capacity, and recovery by column method were studied. The maximum uptake values of MFT resin were found as 60.05 mg Ag+/g by batch method and 11.08 mg Ag+/g, 0.052 mg Zn2+/g, 0.083 mg Cu2+/g and 0.020 mg Ca2+/g by column method. It was seen that MFT resin showed higher uptake behavior for silver(I) ions than base and earth metals due to chelation.

Separation and Recovery of Silver(I) Ions from Base Metal Ions by Thiourea- or Urea-Formaldehyde Chelating Resin

Abstract In the present work, thiourea-formaldehyde (TF) and urea-formaldehyde (UF) chelating resins have been synthesized and they have been used in the adsorptions of Ag(I), Cu(II), and Zn(II) metal ions by batch and column methods. The effect of initial acidity of Ag(I) solution and the adsorption capacities of TF and UF resins by batch method and the separation of Ag(I) ions from Cu(II) and Zn(II) base metal ions by the column method were examined experimentally. The adsorption capacities of TF and UF resins were found as 58.14 and 47.39 mg Ag(I)/g by batch method and 30.7 and 4.66 mg Ag(I)/g, 0.80 and 0.121 mg Cu(II)/g, and under 0.002 mg Zn(II)/g by the column method, respectively. It was found that Ag(I) ions showed higher affinity towards TF resin than UF resin, compared with Cu(II) or Zn(II) ions, and Ag(I) could be separated more effectively by TF resin from Cu(II)and Zn(II) ions.

Selenium levels in breads from Sakarya, Turkey

Selenium (Se) is an important trace element for human and animal health. It accumulates in wheat and corn, which is consumed mostly as bread. The Turkish population consumes mainly white wheat, whole wheat (brown bread) and corn breads. In this study, samples of these breads were collected from six different bakeries in the city of Sakarya, and their selenium levels were determined by ICP–OES after a chemical digestion. It was found that average selenium levels in white wheat, whole wheat and corn breads were 1149, 1204 and 2023 µg/kg, respectively. The results are compared with daily recommended intake and upper tolerable levels for selenium.

Adsorption of Selenite Ions onto Poly(1,8-diaminonaphthalene) Synthesized by Using Ammonium Persulfate

In the present work, poly(1,8-diaminonaphthalene) (poly(1,8-DAN)) was synthesized by chemical oxidation of 1,8-diaminonaphthalene (1,8-DAN) monomer with ammonium persulfate (APS) oxidant and it was used in the adsorption of selenite ions. The polymer samples synthesized at various molar ratios of 1,8-DAN to APS were characterized by FTIR analysis and they were used in the adsorption experiments. The effects of initial acidity, the molar ratio, and initial selenium concentration on the adsorption behavior of poly(1,8-DAN) were examined by using batch adsorption technique. It was found that selenite was adsorbed onto poly(1,8-DAN) in strong acidic conditions (3-8 M HCl). The experimental adsorption data were applied to the Langmuir and Freundlich isotherms. The adsorption capacities of the polymer samples at the molar ratios of 1/0.5 and 1/2 were calculated as 75.19 and 45.05 mg Se/g, respectively. It was estimated that the adsorption mechanisms of selenite ions onto poly(1,8-DAN) were governed by electrostatic interaction (>NH2+SeOCl3−) and piazoselenol type binding (-N=Se=N-).

Quantifying Na(I)-insulin and K(I)-insulin non-covalent complexes by ESI–MS method and calculation of their equilibrium constants

In this study, the dissociation and formation equilibrium constants of Na(I)-insulin and K(I)-insulin complexes have been calculated after the quantifying them on ESI mass spectrometer. The ESI-MS spectra of the complexes were measured by using the solvents as 50% MeOH in water and 100% water. The effect of pH on the Na(I)-insulin and K(I)-insulin complex formation were examined. Serial binding of Na(I) and K(I) ions to the insulin molecule were observed in the ESI-MS measurements. The first formation equilibrium constants were calculated as Kf1: 5.48×103 1/M for Na(I)-insulin complex and Kf1: 4.87×103 1/M for K(I)-insulin in water. The binding capability of Na(I) ions to insulin molecule is higher than the capability of K(I) ions. In case of a comparison together with Ca(II)-insulin and Mg(II)-insulin, the formation equilibrium constants (Kf1) are in order of Ca(II)-insulin>Mg(II)-insulin>Na(I)-insulin>K(I)-insulin in water. The results showed that Na(I) and K(I) ions are involved in the formation of the non-covalent complexes with insulin molecule, since high extracellular and intracellular concentrations of them in the body.

Analysis of dietary minerals in selected seeds and nuts by using ICP-OES and assessment based on the recommended daily intakes

Purpose – Seeds and nuts include many dietary minerals as well as trace metals. It is very important to determine the nutritional mineral values in seeds and nuts. Many minerals can be analyzed simultaneously in low concentrations by using inductively coupled plasma-atomic emission spectroscopy. This paper aims to evaluate nutritional values of dietary and trace minerals in selected seeds and nuts. Design/methodology/approach – Dietary minerals in the sunflower seed (Helianthus annuus), pumpkin seed (Cucurbita pepo L.), peanut (Arachis hypogaea) and corn (Zea mays L.) samples collected from the markets in Sakarya city of Turkey have been analyzed. Two digestion procedures were applied by using hydrochloric acid solution and the mixture of nitric acid and hydrogen peroxide solution. Findings – In the evaluation of the mineral contributions of the nuts, the micro-mineral contributions (Cu, Fe, Zn, Mn and Se) were found at higher values than the macro-minerals (Ca, Mg, K and Na). Potassium was determined as ...

ESI-MS measurements for the equilibrium constants of copper(II)-insulin complexes

Trace elements regulate many biological reactions in the body. Copper(II) is known as one of trace elements and capable of binding to proteins. Insulin is a blood glucose-lowering peptide hormone and it is secreted by the pancreatic β-cells. In this study, Cu(II)-insulin complexes were investigated by using ESI-MS method. Insulin molecule gives ESI-MS peaks at +4, +5, +6 and +7 charged states. Cu(II)-insulin complexes can be monitored and quantified on the ESI-MS spectra as the shifted peaks according to insulin peaks. The solutions of Cu(II)-insulin complexes at different pHs and mole ratios of Cu(II) ions to insulin molecule were measured on the ESI-MS. The highest complex formation ratio for Cu(II)-insulin were found at pH 7. The multiple bindings of Cu(II) ions to insulin molecule was observed. The formation equilibrium constants of Cu(II)-insulin complexes were calculated as Kf1: 3.34 × 104, Kf2: 2.99 × 104, Kf3: 7.00 × 103 and Kf4:2.86 × 103. The specific binding property of Cu(II) ions was controlled by using different spray ion sources including electrospray and nano-electrospray. The binding property of Cu(II) also investigated by MS/MS fragmentation. It was concluded from the ESI-MS measurements that Cu(II) ion has a high affinity to insulin molecules to form stable complexes.

ESI MS for Microsized Bioparticles

An ESI ion trap mass spectrometer was designed for high-throughput and rapid mass analysis of large bioparticles. Mass calibration of the instrument was performed using commercially available polystyrene (PS) microparticles with a size comparable to cancer cells. Different sizes of MCF-7 breast cancer cells (8 to 15 μm) were used in this study. The masses of different cancer cells were measured. This system allows for the analysis of all types of particles.

Analysis of Saccharides by the Addition of Amino Acids

AbstractIn this work, we present the detection sensitivity improvement of electrospray ionization (ESI) mass spectrometry of neutral saccharides in a positive ion mode by the addition of various amino acids. Saccharides of a broad molecular weight range were chosen as the model compounds in the present study. Saccharides provide strong noncovalent interactions with amino acids, and the complex formation enhances the signal intensity and simplifies the mass spectra of saccharides. Polysaccharides provide a polymer-like ESI spectrum with a basic subunit difference between multiply charged chains. The protonated spectra of saccharides are not well identified because of different charge state distributions produced by the same molecules. Depending on the solvent used and other ions or molecules present in the solution, noncovalent interactions with saccharides may occur. These interactions are affected by the addition of amino acids. Amino acids with polar side groups show a strong tendency to interact with saccharides. In particular, serine shows a high tendency to interact with saccharides and significantly improves the detection sensitivity of saccharide compounds. Graphical Abstractᅟ