Nil Ozbek

Method development for the determination of fluorine in toothpaste via molecular absorption of aluminum mono fluoride using a high-resolution continuum source nitrous oxide/acetylene flame atomic absorption spectrophotometer.

Fluorine was determined via the rotational molecular absorption line of aluminum mono fluoride (AlF) generated in C(2)H(2)/N(2)O flame at 227.4613 nm using a high-resolution continuum source flame atomic absorption spectrophotometer (HR-CS-FAAS). The effects of AlF wavelength, burner height, fuel rate (C(2)H(2)/N(2)O) and amount of Al on the accuracy, precision and sensitivity were investigated and optimized. The Al-F absorption band at 227.4613 nm was found to be the most suitable analytical line with respect to sensitivity and spectral interferences. Maximum sensitivity and a good linearity were obtained in acetylene-nitrous oxide flame at a flow rate of 210 L h(-1) and a burner height of 8mm using 3000 mg L(-1) of Al for 10-1000 mg L(-1)of F. The accuracy and precision of the method were tested by analyzing spiked samples and waste water certified reference material. The results were in good agreement with the certified and spiked amounts as well as the precision of several days during this study was satisfactory (RSD<10%). The limit of detection and characteristic concentration of the method were 5.5 mg L(-1) and 72.8 mg L(-1), respectively. Finally, the fluorine concentrations in several toothpaste samples were determined. The results found and given by the producers were not significantly different. The method was simple, fast, accurate and sensitive.

Determination of total sulfur in food samples by solid sampling high-resolution continuum source graphite furnace molecular absorption spectrometry.

The determination of sulfur in food samples via the rotational molecular absorption of carbon monosulfide (CS) was performed using a solid sampling high-resolution continuum source electrothermal atomic absorption spectrophotometer (SS-HR-CS-ETAAS). In the presence of plenty of carbon in the graphite furnace as well as in food samples, CS was formed in the gas phase without the addition of any molecule forming element externally. The effects of the wavelength selected to detect CS, graphite furnace program, amount of sample, coating of the graphite tube and platform with Ir, and the use of a Pd modifier on the accuracy, precision, and sensitivity were investigated and optimized. Sulfur was determined in an iridium-coated graphite tube/platform at 258.056 nm by applying a pyrolysis temperature of 1000 °C and a molecule forming temperature of 2400 °C. The calibration curve prepared from Na2S was linear between 0.01 μg (LOQ) and 10 μg of S. The accuracy of the method was tested by analyzing certified reference spinach and milk powder samples by applying a linear calibration technique prepared from aqueous standard. The results were in good agreement with certified values. The limit of detection and characteristic mass of the method were 3.5 and 8.1 ng of S, respectively. By applying the optimized parameters, the concentrations of S in onion and garlic samples were determined.

Determination of fluorine in milk samples via calcium-monofluoride by electrothermal molecular absorption spectrometry

The determination of fluorine in milk samples via the molecular absorption of calcium mono-fluoride (CaF) was performed using a HR-CS-ETAAS. For this purpose, calcium was pipetted to graphite furnace together with samples. The amount of Ca and the graphite furnace program were optimised. Fluorine was determined in pyrolytically coated platforms at 606.440 nm applying a pyrolysis temperature of 700 °C and a molecule forming temperature of 2250 °C. Finally, applying standard addition technique, F contents of several milk samples were determined. The results obtained by linear calibration and standard addition techniques were significantly different which can be attributed to non-spectral interferences in milk due to matrix concomitants. Therefore, in order to tolerate the errors, the F contents of several milk samples were determined applying standard addition technique. However, since the ingredients of milk samples change for different kinds, the F in each sample was determined from its own standard addition curve. The range of F content for the milk samples were 0.027-0.543 μg mL(-1). The limit of detection and characteristic mass of the method were 0.26 and 0.13 ng of F, respectively.

Microwave plasma atomic emission spectrometric determination of Ca, K and Mg in various cheese varieties.

Microwave plasma-atomic emission spectrometry (MP-AES) was used to determine calcium, magnesium and potassium in various Turkish cheese samples. Cheese samples were dried at 100 °C for 2 days and then digested in a mixture of nitric acid/hydrogen peroxide (3:1). Good linearities (R(2) > 0.999) were obtained up to 10 μg mL(-1) of Ca, Mg and K at 445.478 nm, 285.213 nm and 766.491 nm, respectively. The analytes in a certified reference milk powder sample were determined within the uncertainty limits. Moreover, the analytes added to the cheese samples were recovered quantitatively (>90%). All determinations were performed using aqueous standards for calibration. The LOD values for Ca, Mg and K were 0.036 μg mL(-1), 0.012 μg mL(-1) and 0.190 μg mL(-1), respectively. Concentrations of Ca, K and Mg in various types of cheese samples produced in different regions of Turkey were found between 1.03-3.70, 0.242-0.784 and 0.081-0.303 g kg(-1), respectively.

Method development for the determination of calcium, copper, magnesium, manganese, iron, potassium, phosphorus and zinc in different types of breads by microwave induced plasma-atomic emission spectrometry.

A novel method was developed for the determination of calcium, magnesium, potassium, iron, copper, zinc, and manganese and phosphorous in various kinds of breads samples sold in Turkey by microwave plasma-atomic emission spectrometry (MIP-AES). Breads were dried at 100 °C for one day, ground thoroughly and then digested using nitric acid/hydrogen per oxide (3:1). The analytes in certified reference wheat flour and maize flour samples were determined in the uncertainty limits of the certified values as well as the analytes added to the mixture of ground bread and acid mixture prior to digestion were recovered quantitatively (>90%). Therefore, all determinations were made by linear calibration technique using aqueous standards. The LOD values for Ca, Cu, Fe, K, Mg, Mn, P and Zn were 13.1, 0.28, 4.47, 118, 1.10, 0.41, 7550 and 3.00 ng mL(-1), respectively. No spectral interference was detected at the working wavelengths of the analytes.

Determination of Trace Metals in Waste Water and Their Removal Processes

Since the second part of 20th century, there has been growing concern over the diverse ef‐ fects of heavy metals on humans and aquatic ecosystems. Environmental impact of heavy metals was earlier mostly attributed to industrial sources. In recent years, metal production emissions have decreased in many countries due to strict legislation, improved cleaning/ purification technology and altered industrial activities. Today and in the future, dissipate losses from consumption of various metal containing goods are of most concern. Therefore, regulations for heavy metal containing waste disposal have been tightened [1].

Solid sampling determination of total fluorine in baby food samples by high-resolution continuum source graphite furnace molecular absorption spectrometry

This study describes the applicability of solid sampling technique for the determination of fluorine in various baby foods via molecular absorption of calcium monofluoride generated in a graphite furnace of high-resolution continuum source atomic absorption spectrometry. Fluorine was determined at CaF wavelength, 606.440nm in a graphite tube applying a pyrolysis temperature of 1000°C and a molecule forming temperature of 2200°C. The limit of detection and characteristic mass of the method were 0.20ng and 0.17ng of fluorine, respectively. The fluorine concentrations determined in standard reference sample (bush branches and leaves) were in good agreement with the certified values. By applying the optimized parameters, the concentration of fluorine in various baby foods were determined. The fluorine concentrations were ranged from <LOQ to 3.75μgg(-1). Owing to the ultra low sample amounts used in solid sampling analysis, micro-scale distribution of fluorine in the samples was also determined.

A new approach for the determination of sulphur in food samples by high-resolution continuum source flame atomic absorption spectrometer

The new approach for the determination of sulphur in foods was developed, and the sulphur concentrations of various fresh and dried food samples determined using a high-resolution continuum source flame atomic absorption spectrometer with an air/acetylene flame. The proposed method was optimised and the validated using standard reference materials, and certified values were found to be within the 95% confidence interval. The sulphur content of foods ranged from less than the LOD to 1.5mgg(-1). The method is accurate, fast, simple and sensitive.

A study to visualize and determine the sequencing of intersecting ink lines

Determining the sequencing of intersecting ink lines is one of the current problems for forensic document examiners. The way two inks will distribute and interact with each other and the paper at the crossing is a dynamic process that can be affected by many variables. Thus, the main purpose of this manuscript is to visualize and have a more comprehensive understanding of this process as well as study a methodology for determining the correct order of intersecting ink lines. For this, overlapping layers of different types of inks from writing instruments and printers were cross-sectioned and examined with a microscope. Results from pen/pen crossings showed that liquid-liquid and gel-gel intersections tended to form a double layer but oil-oil intersections usually formed mixtures. Additionally, oil-liquid and oil-gel intersections tended to form a double layer whenever the oil ink was on top and liquid-gel intersections tended to form a double layer for almost all crossings with exception of the ones involving a gel pen ink from one manufacturer. Results from pen/printer crossings showed the formation of a double layer only when the printer ink was on top of the pen ink. On the other permutation, the pen ink tended to penetrate through the printer ink producing the mixture of both inks. The inks drying time was found to be an important factor affecting the interaction between two inks in a crossing, particularly crossings involving gel pen inks. On the contrary, the type of paper and the writing pressure showed no significant influence on the inks distribution at the crossing. The methodology developed was reproducible with overlapping layers but there were many experimental difficulties during the validation process of intersections representing real crossings. Moreover, interpretation was dependent on the operators eye which was a limiting factor.

Direct determination of lead in plastic toys by solid sampling high resolution-continuum source graphite furnace atomic absorption spectrometry

In this study, lead concentrations in various plastic toys were determined directly by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry. The toys were cut into small pieces and introduced into the graphite furnace between 0.05 and 0.7 mg without any further treatment. Lead was determined at 217.005 nm using a Pd + Mg modifier. The samples were pyrolyzed at 1000 °C and atomized at 2200 °C with or without gas flow at the atomization stage depending on the concentration of the analyte. The lead concentration in a certified reference plastic material (ERM-EC680K) was determined in the uncertainty limits of the certified value. The limits of detection in gas-stop and gas-flow modes for 0.7 mg of sample were 0.037 and 0.93 mg kg−1, respectively. The concentrations of lead in plastic toys of different colours were found to be in the range of 0.060–9.12 mg kg−1.