Hayati Sari

Microwave and Wet Digestion Procedures for Atomic Absorption Spectrometric Determination of Trace Metals Contents of Sediment Samples

Abstract The comparison of wet digestion and microwave digestion of Cd, Co, Cr, Cu, Mn, Pb, Zn, Fe, and Ni contents of the river bottom and sea floor sediments from the various locations of Turkey was performed in the present work. After digestions, the heavy metal concentrations were determined by flame atomic absorption spectrometry (FAAS). The heating programs for microwave digestion, different combinations, and volumes of acid mixtures were evaluated for microwave digestion efficiency. The studies in the present work show that the microwave‐assisted digestions in closed system are easier and faster than the wet digestion. Also the results found by the microwave and the wet digestions were reliable and accurate. The procedures were also checked with two‐stream sediment reference material (GBW 07309 and GBW 07310). Results for standard reference material (SRM) were in good agreement with certified values. The relative standard deviations for all metal concentrations were found to be lower than 10%.

Atomic Absorption Spectrometric Determination of Trace Metal Contents of Mushroom Samples from Tokat, Turkey

Abstract Six trace metals (Fe, Cu, Mn, Zn, Pb, Cd) were determined in 12 different mushroom samples collected from polluted and unpolluted locations in Tokat, Turkey using flame and graphite furnace atomic absorption spectrometry after dry ashing, wet ashing and microwave digestion. The study of sample preparation procedures showed that the microwave digestion method was the best. The proposed method showed satisfactory recovery, detection limits and standard deviation for trace metals determination in mushroom samples. The results were in the ppm range 184–7560 (Fe), 12–181 (Cu), 16–122 (Mn), 18–403 (Zn), 0.75–7.77 (Pb), and 0.14–5.50 (Cd).

Synthesis, antimicrobial activity and acid dissociation constants of methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives

In this study, a series of polysubstituted methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives were designed and synthesized by the cyclization reaction of methyl 1-(benzoylcarbamothioyl)-5,5-diphenylpyrrolidine-2-carboxylates and 2-bromo-1-(4-substituted phenyl)ethanones in 70-96% yield. The starting pyrrolidine derivatives were synthesized via a 1,3-dipolar cycloaddition reaction in 83-88% yield. The stereochemistry of one of these methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives was characterized by a single crystal X-ray diffraction study and the acid dissociation constants of these compounds were determined. An antimicrobial screening was performed against different bacterial and fungal strains and against the M. tuberculosis H37Rv strain. Interesting antibacterial activity was observed for two compounds against the A. baumannii strain with MIC values of 31.25 µg/mL (Ampicillin: 125 µg/mL) and against the M. tuberculosis H37Rv strain with MIC values of 0.98-1.96 µg/mL (Isoniazid: 0.98 µg/mL, Ethambutol: 1.96 µg/mL). Therefore, these structures can be considered as good starting points for the development of new powerful antimycobacterial agents.

Determination of Acid Dissociation Constants (pKa) of Bicyclic Thiohydantoin-Pyrrolidine Compounds in 20% Ethanol-Water Hydroorganic Solvent

The acid dissociation constants of potential bioactive fused ring thiohydantoin-pyrrolidine compounds were determined by potentiometric titration in 20% (v/v) ethanol-water mixed at 25 ± 0.1°C, at an ionic background of 0.1 mol/L of NaCl using the HYPERQUAD computer program. Proton affinities of potential donor atoms of the ligands were calculated by AM1 and PM3 semiempiric methods. We found, potentiometrically, three different acid dissociation constants for 1a–f. We suggest that these acid dissociation constants are related to the carboxyl, enol, and amino groups.

Cadmium and phosphorus accumulates in soil under intensive cultivation in Turkey

Continuous population growth and increasing standard of living in the world increase the use of mineral fertilizers in agricultural areas. Since cultivated areas are not expected to expand, it will be necessary to intensify agricultural production, wherein fertilizer will be play a vital role (Tisdale et al., 1993). Phosphorus fertilizers applied for increasing yield may cause increasing Cd levels on agricultural land. The rate of this increase depends on application rates of phosphorus fertilizers and soil characteristics (Hashemi, 1996; Taylor, 1997). Cadmium in phosphorus fertilizers derives principally from the phosphate rock which is used for P fertilizer production (Camelo et al., 1997). As phosphorus fertilizers contain higher concentrations of Cd than those present in the soil, their application, over time, increases soil Cd concentrations (Williams & David, 1973; Taylor, 1997; Laegreid et al., 1999). Conversely, Jeng & Singh (1995) reported that long-term fertilizer P application did not elevate Cd accumulation in soils. This might be the result of using P fertilizers containing lower rates of Cd, or plant uptake and removal of Cd by leaching (Mann et al., 2002). Cadmium is a heavy metal that can be taken up from soils by plant roots, and increasing intake of cadmium with agricultural foods may affect human health. Therefore, there is a need to limit Cd levels in food (Loganathan & Hedley, 1997). Cadmium can be bound in soil by simple electrostatic forces, or by association with metal oxides, carbonates, and organic matter (Martin et al., 2002). Cadmium solubility in soil depends on soil pH and other factors. Soil Cd concentration decreases with increasing soil pH (Christensen, 1989). The high pH and CaCO3 contents in soils may elevate adsorption rates for P and Cd by the formation of a surface complex of CaCO3 P and Cd (Cole & Olsen, 1959; Afif et al., 1993; Hooda & Alloway, 1998; Ramachandran & D’Souza, 1998). Long-term application of P fertilizers in excess of plant needs may raise the level of surplus P in soils. The increase in soil P content may cause increasing P loss by leaching (Hooda et al., 1999). Determination of polluting factors in agricultural areas and taking necessary precautions against those factors are vital for the future of sustainable agriculture. There are many researches related to soil available and total P contents in agricultural areas in Turkey. However, little research has been carried out in relation to Cd content in the same areas. Therefore, the objective of this study is to investigate the effect of long-term application of P fertilizers on soil Cd and P *Corresponding author. kadirs@gop.edu.tr Saltali, K., Sari, H., Mendil, D. and Altin, S. (Department of Soil Science, Faculty of Agriculture, University of Gaziosmanpasa, TR-60240 Tokat, Turkey and Department of Chemistry, Faculty of Science and Art, University of Gaziosmanpasa, TR-60240 Tokat, Turkey). Cadmium and phosphorus accumulates in soil under intensive cultivation in Turkey. Accepted May 4, 2004. Acta Agric. Scand., Sect. B, Soil and Plant Sci. 54: 267 /272, 2004. # 2004 Taylor & Francis. Kadir Saltali*, Hayati Sari, Durali Mendil and Serap Altin Department of Soil Science, Faculty of Agriculture, University of Gaziosmanpasa, TR-60240 Tokat, Turkey and Department of Chemistry, Faculty of Science and Art, University of Gaziosmanpasa, TR-60240 Tokat, Turkey

Acid Dissociation Constants of 5,5-Diphenylpyrrolidine N-Aroylthioureas and Stability Constants of their Pt(II) and Ni(II) Complexes in Acetonitrile-Water Hydroorganic Solvent

In this study, acid dissociation constants of 5,5-diphenylpyrrolidine N -aroylthiourea derivatives, exhibiting anti(myco)bacterial activity, were determined by potentiometric titration in 30% (v/v) acetonitrile-water hydroorganic solventat 25 ± 0.1 °C , at an ionic background of 0.1 mol / L of NaCl using the HYPERQUAD computer program. Three acid dissociation constants were determined for each compound 1a-e and we suggest that these acid dissociation constants are related to the carboxyl, enol and enthiol groups. Stability constants of their Pt(II) and Ni(II) complexes were also determined by potentiometric titration under the same conditions stated above using the HYPERQUAD computer program. The ligands behave as bidentate and bind to the metal atom via the S and O atoms. In various pH conditions, the different complex forms were formulated as ML 2 , MHL 2 , MH 2 L 2 , MH 3 L 2 , MH 4 L 2 , MH 5 L 2 and MH -4 L 2 between Pt 2+ /Ni 2+ ions and 5,5-diphenylpyrrolidine N -aroylthioureas. Stability constants of the complexes show that the ligands 1a-e form complexes with Pt(II) and Ni(II) metals as 2:1. The stability of the complexes formed by the ligands and platinum were found to follow the order: 3d > 3a > 3e > 3c > 3b . The stability of the complexes formed by the ligands and nickel were found to follow the order: 4d > 4c > 4a > 4b > 4e . As a result, generally the platinum complexes formed with these ligands are more stable than their nickel complexes.