Firat Aydin

A sequential extraction to determine the distribution of phosphorus in the seawater and marine surface sediment

The distribution of phosphorus species among environmental compartments (e.g., between water and sediment), significantly affects the bioavailability of these species to organisms. The eastern Mediterranean Sea is one of the most extreme oligotrophic oceanic regions on earth in terms of nutrient concentrations and primary productivity. The paper presents the results of inorganic and organic forms in surface sediment and seawater from NE Mediterranean Sea (Burclar Bay, Erdemli, South Anatolia of Turkey) in May 2007. Speciation of phosphorus in seawater and surface sediment using inductively coupled plasma-atomic emission spectrometer (ICP-AES) has been reported here. The method is based on sequential extractions of the seawater and sediment each releasing four forms of inorganic phosphorus: loosely sorbed phosphorus, phosphorus bound to aluminium (P-Al), phosphorus bound to iron (P-Fe) and phosphorus bound to calcium (P-Ca). The most abundant form of inorganic phosphorus in the seawater and surface sediment is calcium-bound phosphorus. Relative abundances of the remaining phosphorus forms in sediment follow the order: P-Al>P-Fe>loosely bound-P and in seawater follow the order P-Fe>P-Al>loosely bound-P.

Cold vapour generation and on-line trapping of cadmium species on quartz surface prior to detection by atomic absorption spectrometry

A quartz trap for on-line preconcentration of Cd species was designed. The cold vapour generation technique was used for the generation of Cd species. The trapping medium was formed by external heating of the inlet arm of a quartz T-tube. The generated analyte species were trapped on a quartz surface heated to the collection temperature, 350 °C, and the collected species were revolatilized when the trap was heated further to revolatilization temperature, 1000 °C, and hydrogen gas was introduced in the trapping medium. Two-level fractional factorial design and central composite design were used to optimize generation conditions in the flow injection mode. The results of the fractional factorial design demonstrated that the factors and their interactions were statistically significant. Three factors, length of reaction coil, carrier HCl concentration and NaBH4 concentration, were considered to be the most significant parameters in the optimization and their optimum values were found to be 30 cm, 0.3 M and 3% (m/v), respectively. Sea-water (BCR), tomato leaves (NIST 1573a) and oyster tissue (NIST 1566b) standard reference materials were analyzed to assess the accuracy of the proposed method. For a collection period of 3.0 min, i.e., 6.0 ml sample volume, the 3σ limit of detection was 1.8 pg ml−1; the enhancement factor for LOD was found to be 90 as compared with FI-HGAAS. The sample throughput rate was 12 h−1.

Aflatoxin species: their health effects and determination methods in different foodstuffs

AbstractCarcinogenic and mutagenic properties of aflatoxin species are known in literature. Their intake over a long time period might be health-dangerous for human even at trace levels. It is well known that different foodstuffs can be contaminated by aflatoxin species through growing and storage. Due to the serious health effects, sensitive determination of aflatoxin species in any matrices related with the human being is very crucial at trace levels. In literature, there are sensitive techniques to analyze the different samples for the contents of their aflatoxin species. Each technique has some advantages and disadvantages over the other techniques. This review aims to summarize the different health effects of aflatoxin species, development of analytical techniques and applications of developed techniques in a variety of matrices.

From mg/kg to pg/kg Levels: A Story of Trace Element Determination: A Review

Abstract Determination of the trace elements in a variety of environmental samples is of great importance. Most elements, including iron, calcium, and selenium, are crucial for the regulation of human mechanisms, and many others, like lead and cadmium, are toxic even at trace levels. Some elements, like selenium, have a narrow margin of safety. Hence, determination of elements at trace levels is crucial in any matrix related to humans. Trace element determination requires sufficiently sensitive procedures to monitor trace levels. This review aims to highlight not only the development in instrumentation for ultratrace element determination in variety of matrices but the application of developed techniques. Advantages and disadvantages of the techniques are also discussed.

Comparison of the biodiesel quality produced from refined sunflower (Helianthus annuus L) oil and waste cooking oil

A major hurdle in commercialization of biodiesel from vegetable oil, in comparison to petroleum-based diesel fuel, is its cost of manufacturing, primarily the raw material cost. Waste cooking oil is one of the economical sources for biodiesel production. NaOH and KOH catalyzed processes for prepared of biodiesel expressed of fatty acid methyl ester were comparatively studied for refined sunflower (Helianthus annuus L) oil and waste cooking oil. Transesterification was carried out using 100% excess methanol; i.e. molar ratio of methanol to oil is 6:1 and catalyst concentration of 0.5% at 60°C. Fuel properties and specifications such as viscosity, flash point, cloud point, pour point, density, cetane number, and acidic value are determined and compared to each other and petroleum diesel. This study characterizes the fuel properties of biodiesel produced from refined sunflower oil and waste cooking oil using two different catalysts (NaOH and KOH) to provide a comprehensive understanding of biodiesels.

Synthesis, spectroscopic and thermodynamic studies of new transition metal complexes with N,N′-bis(2-hydroxynaphthalin-1-carbaldehydene)-1,2-bis(m-aminophenoxy)ethane and their determination by spectrophotometric methods

A novel tetradentate N2O2-type Schiff base, synthesized from 1,2-bis(m-aminophenoxy)ethane and 2-hydroxynaphthalin-1-carbaldehyde, forms stable complexes with transition metal ions such as Cu(II), VO(IV) and Zn(II) in DMF. Microanalytical data, elemental analysis, magnetic measurements, UV, visible and IR spectra as well as conductance measurements were used to confirm the structures. The stability constants of these complexes in 60% (v/v) DMF–water were determined at different ionic strengths (0.07, 0.13, 0.2 M) and at different temperatures (45, 50, 55, 60 ± 0.1°C) using a spectrophotometric method. From these constants, thermodynamic stability constants and thermodynamic parameters (ΔG 0, ΔH 0, ΔS 0) were calculated. The values of enthalpy change are negative for all systems. The acid dissociation constant of the ligand, investigated in 60% (v/v) DMF–water, has also been calculated at different temperatures.

Optimization of Continuous Flow Hydride Generation Inductively Coupled Plasma Optical Emission Spectrometry for Sensitivity Improvement of Bismuth

Experimental variables in continuous flow hydride generation inductively coupled plasma-optical emission spectrometry (CF-HG-ICP-OES) were optimized for determination of bismuth. Concentrations of NaBH4, HCl, and NaOH, flow rates of NaBH4, sample solution, waste and carrier argon, radio frequency power, lengths of reaction, and stripping coils were optimized to obtain lower detection limits. Under optimum conditions, the detection limit was calculated as 0.16 ng mL−1, and the calibration plot was linear between 1.0–50.0 ng mL−1. An improvement in detection limit of 5.75 times by CF-HG-ICP-OES was reached vs. ICP-OES. Relative standard deviation (RSD) for ten replicate measurements of 10.0 ng mL−1 Bi was calculated as 3.9%. Effect of possible interferic ions on Bi signal was evaluated. Accuracy of method was verified by using a standard reference material, SRM 1643e. Results found for Bi were in satisfactory agreement with certified values. The proposed method was then employed to determine trace concentration of Bi in milk samples. Bi amounts in samples were found in the range from lower than the quantitation limit to 14.5 ng mL−1, whereas Bi concentrations were lower than the detection limit in three samples.

Synthesis, spectral studies, and determination of stability constants and thermodynamic parameters for some aromatic diamine transition-metal complexes

The Cu(II) and Zn(II) complexes of aromatic bidentate diamines were prepared and characterized by different analytical and spectral methods. Thermodynamic parameters of complexes of Cu(II) and Zn(II) cations with 1,3-bis(p-aminophenoxy)propane were determined in 60 vol. % DMF-H2O at various ionic strengths (0.07, 0.13, 0.2 M NaNO3) and different temperatures (45, 50, 55, 60 ± 0.1°C) using a spectrophotometric method. The NaNO3 solution was used to maintain the ionic strength. The stability constants show an inverse relationship with ionic strengths. The thermodynamic parameters of 60 vol. % DMF-H2O (ΔG°, ΔH°, ΔS°) based on these formation constants were determined.

A new method to reduce false positives due to antimony in detection of gunshot residues.

False positives due to the presence of antimony in vehicle seat fabrics are a problem in gunshot residue (GSR) analysis, in particular, when graphite furnace atomic absorption spectrometry (GFAAS) is employed. In this study, we sought to determine the reason for the prevalence of false positive results and to propose a new approach for the analysis of GSR on vehicle seats. GFAAS was used to examine adhesive tape swabs collected from 100 seats of 50 different automobiles. Characterization of seat fabrics was carried out by using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy with energy dispersive X-ray (SEM/EDX) spectroscopy. The results of FTIR analysis indicated that all seat covers containing antimony were composed of polyester. Experimental results obtained by SEM/EDX analysis revealed that the fabrics in these seat covers contained evenly distributed antimony within the structure of polyester fibers. This study shows that the type of seat fabric should be determined by FTIR spectroscopy before elemental GSR analysis. In this way, most of the false positives caused by polyester fibers in GSR analysis can be prevented.

The basic properties of transesterified corn oil and biodiesel-diesel blends.

Abstract Biodiesel, one of green fuels and clean energies, is compatible with traditional petroleum-based diesel and both can be completely blended without any stratification. Biodiesel was prepared from corn by transesterification of the crude oil with methanol in the presence of NaOH as catalyst. Transesterified corn oil has better properties globally because it has the greater monounsaturated content. Determination of blend levels is one important issue to the quality control of biodiesel due to the increase of biodiesel-diesel blends commercialization. The objective of this study was to characterize how the key fuel properties changed when the commercial petroleum diesel fuel was blended with methyl ester produced from corn oil. In the present study, commercially available diesel fuel was blended with the biodiesel prepared from corn oil. The blends of biodiesel petroleum diesel were prepared on a volume basis. The important properties of corn oil methyl ester (biodiesel)-diesel fuel blends, such as density and kinematic viscosity, are found out and compared to those of No. 2 petroleum diesel, ASTM, and EN biodiesel standards.