Mehmet Tufekci

Simultaneous preconcentration of Co(II), Ni(II), Cu(II), and Cd(II) from environmental samples on Amberlite XAD-2000 column and determination by FAAS

A new method for the preconcentration of some trace metals (Co, Ni, Cu, and Cd) as complexed with ammonium pyrrolidynedithiocarbamate (APDC) was developed using a mini-column filled with Amberlite XAD-2000 resin. Metal contents were determined by flame atomic absorption spectrometry (FAAS) after the metal complexes accumulated on the resin were eluted with 1M HNO(3) in acetone. The effects of the analytical parameters such as sample pH, quantity of complexing agent, eluent type, resin quantity, sample volume, sample flow rate, and matrix ions were investigated on the recovery of the metals from aqueous solutions. The relative standard deviation (R.S.D.) of the method was <6%. The validation of the method was confirmed using two certified reference materials (CRM TMDW-500 Drinking Water and CRM SA-C Sandy Soil C). The method was successfully applied to some stream waters and mushroom samples from Eastern Black Sea Region (Trabzon city) of Turkey.

Proximate composition and selected mineral content of commercially important fish species from the black sea

Proximate composition, selected mineral (Zn, Fe, Cd, As, Hg, Pb, Ni, Cu) content and fatty acid profiles were determined in some widely consumed fish species obtained from the Black Sea. All fish species analysed individually were fairly high in protein (14·1–25·1%) and lipid (7·4–18·4%). Moisture and ash content varied within a narrow range. The mineral content was highly variable. The most abundant microelements in fish were Zn and Fe followed by Cu, and the remaining elements were present in amounts below toxic levels. Eight fatty acids (16: 0, 16:1, n-7, 18: 0, 18:1 n-9, 18: 2 n-6, 20:1 n-9, 20: 5 n-3, 22: 6 n-3) represented more than 60% of the fatty acid content. Saturated fatty acids ranged from 25·8 to 45·1%. Anchovy and whiting contained almost 35% of polyunsaturated fatty acids. The percentage of docosahexaenoic acid (DHA) exceeded that of eicosapentaenoic acid (EPA) in almost all the fish species examined, and the actual content of these acids has shown that sprat, whiting, garfish, red mullet, shad and sea bream provide the recommended daily intake of 1 g of EPA+DHA with reasonable amounts of fillet. These results indicate that biological differences existing in fish species can influence the values to be set for the standards and composition.

Preconcentration, separation and spectrophotometric determination of aluminium(III) in water samples and dialysis concentrates at trace levels with 8-hydroxyquinoline-cobalt(II) coprecipitation system.

A separation-preconcentration procedure was developed for the determination of trace amounts of aluminium in water samples and dialysis concentrates by UV-vis Spectrophotometry after coprecipitation using 8-hydroxyquinoline (8-HQ) as a chelating agent and Co(II) as a carrier element. This procedure is based on filtration of the solution containing precipitate on a cellulose nitrate membrane filter following aluminium(III) coprecipitation with Co/8-HQ and then the precipitates together with membrane filter were dissolved in concentrated nitric acid. The metal contents of the final solution were determined by UV-vis Spectrophotometry with Erio Chrome Cyanine-R standard method. Several parameters including pH of sample solution, amount of carrier element and reagent, standing time, sample volume for precipitation and the effects of diverse ions were examined. The enrichment factor was calculated as 50 and the detection limits, corresponding to three times the standard deviation of the blank (N: 10), was found to be 0.2 microg L(-1). The accuracy of the method was tested with standard reference material (CRM-TMDW-500) and spiked addition. Determination of aluminium(III) was carried out in sea water, river water, tap water and haemodialysis fluids samples. The recoveries were >95%. The relative standard deviations of determination were less than 6%.

Spectrophotometric determination of copper in pharmaceutical and biological samples with 3-[2-[2-(2-hydroxyimino-1-methyl-propylideneamino)-(ethylamino]-ethyl-imino]-butan-2-one oxime).

3-[2-[2-(2-hydroxyimino-1-methyl-propylideneamino)-ethylamino]-ethyl-imino]-butan-2-one oxime, (H(2)mdo) reacts with copper(II) to form a highly stable 1:1 complex in alkaline medium at room temperature. The complex gives a maximum absorption at 570 nm with a molar absorptivity coefficient of 0.16 x 10(4) l mol(-1) cm(-1). A spectrophotometric method using this ligand was developed and optimized in terms of pH, stability of the complex, amount of reagent required, sensitivity, linearity and tolerance limits of various foreign ions. The linear range for copper determination is 0.2-225 mg l(-1). The method is sensitive, accurate and tolerant to many foreign substances, and, all the reagents used are stable under the conditions. Moreover, the method is easy to perform for the determination of copper in pharmaceutical and biological samples.

Synthesis and complex formation of novel 12-membered macrocyclic (E,E)-dioximes

Abstract Dibenzo[e,k]-2,3-bis(hydroxyimino) 1.4.7.10-tetrathia-2,3,8,9-tetrahydrocyclododecine (S4H2) and dibenzo-[e,k]-2,3-bis(hydroxyimino)-1,4-dithia-7,10-dioxa-2,3,8,9- tetrahydrocyclododecine (O2S2H2) have been prepared from (E,E)-dichloroglyoxime, 2,3,8,9-dibenzo-1,4,7,10-tetrathiadecane (DTT) and 2,3,8,9-Dibenzo-4,7-dioxa-1,10-dithiadecane (DDD) which was synthesized by treating 1,2-bis(o-aminophenoxy)ethane with HNO2 and potassium ethylxsanthate. The structures of these vic-dioximes have been determined as the (E,E)-forms according to 1H-NMR and IR data. Only mononuclear complexes with a metal-ligand ratio of 1:2 have been isolated with Co(II), such as [(S4H)2Co(III)L′Cl] and [(O2S2H)2Co(III)L′Cl]; Cu(II) forms only trinuclear complexes. Reaction of the mononuclear complexes with Pd(II) gives heterotrinuclear complexes.

The determination of optimum fermentation time in Turkish black tea manufacture

In recent years, Turkish black tea has been manufactured by a combination of orthodox + rotorvane + orthodox systems, especially developed for the conditions of Turkey. The optimum fermentation time of black tea manufactured by this system was investigated at the factory level by measuring the theaflavin contents during the fermentation step, which starts with rolling and ends with drying processes. Optimum fermentation times from the start of rolling in the ORO system were determined to be 83 min and 80 min for coarse tea and sieved fine tea, respectively, by theaflavin analysis. Low levels of theaflavin in Turkish black tea were attributed to the very low quality of the fresh tea leaves and of the plucking standards.

Simultaneous separation and preconcentration of Cd(II), Co(II), and Ni(II) ions in environmental samples by carrier element-free coprecipitation method prior to their flame atomic absorption spectrometric determination

ABSTRACTIn the present study, Cd(II), Co(II), and Ni(II) ions were separated and preconcentrated via carrier element-free coprecipitation (CEFC) method by using an organic coprecipitating agent, 1,2-bis-(2-tosyl ethoxy) benzene (BTEB), prior to their flame atomic absorption spectrometric (FAAS) detections. The experimental conditions were optimized in terms of pH of the aqueous solution, BTEB amount, standing time, centrifugation rate and time, and sample volume. Under the optimum experimental conditions, the detection limits for Cd(II), Co(II), and Ni(II) ions were found to be 0.13, 0.67, and 0.46 μg L−1, respectively, and the relative standard deviations for the analyte ions were found to be lower than 4.0%. The accuracy of the method was tested by analyzing certified reference material and spike tests. The method was applied to determine the levels of Cd(II), Co(II), and Ni(II) ions in sea and stream water, macaroni, red lentil, and cracked wheat samples.

Separation and pre-concentration of palladium(II) from environmental and industrial samples by formation of a derivative of 1,2,4-triazole complex on Amberlite XAD–2010 resin

A simple separation/pre-concentration method was developed for extraction of Pd(II) in various environmental samples, based on its adsorption of 4–phenyl–5–{[(4–phenyl–5–pyridin–4–yl–4H–1,2,4–triazole–3–yl)thio]methyl}–4H–1,2,4–triazole–3–thyol (PPTTMET) complex on Amberlite XAD–2010 resin in a mini column. The ligand has high affinity for Pd(II) among many other metals that are taken into consideration. The flame atomic absorption spectrometry is employed to determine the concentration of Pd(II). The optimum working conditions which were determined are as follows: 0.05 mol L−1 HNO3 as working medium, 1.0 mol L−1 HCI in acetone as elution solvent, 0.75 mg of PPTTMET amount and 750 mL of sample volume. The system was independent from the flow rates between 3.1 and 23.1 mL min−1. The Pd(II) adsorption capacity of Amberlite XAD–2010 resin was found to be 12.8 mg g−1 and the enrichment factor was calculated as 375. The method was successfully applied for the determination of Pd(II) in motorway dust samples, anodic sludge, gold ore, industrial electronic waste materials and various water samples.

Removal of chlorine residues in aqueous media by metallic iron

Abstract In the present research, granular metallic iron was used to reduce the chlorine species into chloride in chlorine solutions. Optimum conditions were investigated with regard to pH, particle size, and contact period It was determined that the species of OCl − and HOCl were removed by 100% between pH 4 and 7 within 25 min.

Synthesis of Novel Homo and Heterobimetallic Complexes of Ferrocenyl Formazans

Abstract 1-(o-Carboxyphenyl)-5-(p-hydroxy-o-carboxyphenyl)-3-ferrocenyl-formazan (HFF) and l-(o-carboxyphenyl)-5-(p-nitro-o-carboxyphenyl)-3-ferrocenylformazan (NFF) have been synthesized by the addition reaction of the diazonium salts of 2-amino-5-hydroxybenzoic acid, 2-ami-no-5-nitrobenzoic acid and ferrocenaldehyde-2-carboxyphenylhydrazone. The Ni(II), Pd(II), and Fe(II) complexes of HFF and NFF have also been obtained. The structures of formazans and their transition metal complexes were confirmed by elemental analyses, 1H and 13C-NMR, IR and UV-VIS. spectral data.