Browsing by Author "Aycan, S"

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    Polarographic determination of fluvoxamine maleate in tablets
    Elmali, F; Alpdogan, G; Sungur, S; Aycan, S
    The differential pulse polarographic (DPP) method was developed for the determination of fluvoxamine maleate (I). At pH = 3. 7, (I) give a peak at - 0. 73 V in aqueous solution. The developed method was applied to the assay of the drug substance in commercial tablet formulations. The results were statistically compared with those obtained by reference methods (HPLC and direct current polarographic method) using t- and F- tests at 95 % confidence level.
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    The contents of sesamol and related lignans in sesame, tahina and halva as determined by a newly developed polarographic and stripping voltametric analysis
    Tokusoglu, O; Kocak, S; Aycan, S
    The contents of antioxidant lignans (Sesamol) in sesame, commercial formulations of tahina and halva, which are processed tahina foods, were determined by Differential Pulse Polarography (DPP) with a capillary hanging mercury drop electrode (HMDE). A platinum wire was used as the counter electrode and Ag/AgCl was the reference electrode. Samples have been analyzed by standard addition procedures and found to be quantitative (p<0.01). Due to the fact that sesamo is an oil-soluble phenolic compound, it was found in the oil levels of sesame, tahina and halvas. Sesame samples contained 51.05-56.46 % in oil whereas tahina samples contained 52.12-53.79 % in oil. The oil percentage of plain halva was found to be 28.79 - 30.13 % (p<0.01). Phenolic lignan sesamol in sesame was 0.26-0.32 mg/100g oil, whereas the sesamol in tahina was 10.98-12.33 mg/100g oil. The sesamol in commercial plain halva samples and the open marketed plain halva samples contained 8.24-9.12 mg/100g oil and 4.97 mg sesamol /100g oil, respectively (R-2=0.9999) (p<0.01). The proposed Differential Pulse Polarographic (DPP) method is a rapid, reproducible procedure for the simultaneous determination of phenolic lignans in sesame and food products with sesame. It provides an adequate, sensitive, quantitative detection of these nutraceuticals in the commercial food industry.
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    Enhanced optical oxygen sensing using a newly synthesized ruthenium complex together with oxygen carriers
    Ertekin, K; Kocak, S; Ozer, MS; Aycan, S; Cetinkaya, B
    In this article, an emission based, simple and fast method is proposed for the determination of gaseous oxygen. A newly synthesized fluorophore dichloro-{2,6-bis[1-(4-dimethylamino-phenylimino) ethyl]pyridine} ruthenium(II) has been used for oxygen sensing together with oxygen carrier perfluorochemicals (PFCs) in silicon matrix. It should be noted that the solubility of oxygen in fluorocarbons is about three to ten times large as that observed in the parent hydrocarbons or in water. respectively. Employed PFCs are chemically and biochemically inert, have high dissolution capacities for oxygen. and, once doped into sensing film, considerably enhance the response of sensing agent. (C) 2003 Elsevier B.V. All rights reserved.
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    Determination of pKa Values of Clinically Important Perfluorochemicals in Nonaqueous Media
    Hakli, O; Ertekin, K; Ozer, MS; Aycan, S
    Perfluorochemicals (PFCs) are clinically and biotechnologically important species. In this work, the potentiometric titration method in nonaqueous media is proposed for the determination of acidity constant values of six different perfluorinated compounds. The saturated and nonsaturated perfluoroacids, perfluorocarnosine, and perfluoroalkyl-beta-alanine were potentiometrically titrated in acetonitrile, N,N-dimethylfornamide, acetone, ethanol, methanol, and pyridine with tetrabutylammonium hydroxide. The half-neutralization potentials and acidity constants of PFCs have been calculated from the titration curves by using the computerized derivative method. Except for R-F-Carnosine, all of the potentiometric fitration curves of the PFCs exhibited one stoichiometric and well-defined endpoints in all of the solvents employed. The reproducibility and sensitivity of the method were evaluated.
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    Simultaneous differential pulse polarographic determination of cadmium, lead, and copper in milk and dairy products
    Tokusoglu, Ö; Aycan, S; Akalin, S; Koçak, S; Ersoy, N
    The contents of potentially toxic elements lead and cadmium and the essential element copper in various milk and dairy products consumed in Turkey were determined by differential pulse polarography (DPP), primarily to assess whether the intakes comply with recommended desired concentrations for essential and permissible levels for toxic elements. A simple and rapid DPP method has been developed for the simultaneous determination of cadmium, lead, and copper in samples. Using the differential pulse mode, half-wave peak potentials as E-1/2 were -0.58, -0.40, and -0.07 V for cadmium (Cd), lead (Pb), and copper (Cu), respectively. Marketed formulations of dairy products have been analyzed by calibration and standard addition methods. Recovery experiments were found to be quantitative. The linear domain ranges were 0.00-674.28 mug/L for Cd (R-2 = 0.9999), 0.19-2.94 mg/L (p < 0.01) for Pb (R-2 = 0.9997), and 0.41 -133.46 mug/L for Cu (p < 0.01) (R-2 = 0.9999). The studies have shown that the method is a rapid, reproducible, and accurate determination of these elements in milk and dairy products and can be used in the analysis of marketed formulations in the milk and dairy industry.
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    Differential pulse polarographic determination of enalapril maleate
    Elmali, F; Alpdogan, G; Aycan, S; Sungur, S
    A differential pulse polarographic (DPP) method has been developed for the quantitative analysis of enalapril maleate. Enalapril maleate gives a peak at -1.4 V in methanol. A calibration curve was constructed for the 20 -100 mug ml(-1) concentration range. As a reference method, a reversed phase high performance liquid chromatographic procedure has been developed. Commercially available tablets were analysed by the two methods. Statistical evaluations indicated that there was no significant difference between the mean values and precisions of the two methods at a 95% confidence level.
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    Occurrence of conjugated linoleic acid in probiotic yoghurts supplemented with fructooligosaccharide
    Akalin, AS; Tokusoglu, Ö; Gönc, S; Aycan, S
    A gas chromatographic procedure was used for the analysis of conjugated linoleic acid (CLA) isomers, c9t11-CLA and t10c12-CLA, in yoghurts containing Lactobacillus acidophilus or Bifidobacterium animalis and/or 2% fructooligosaccharide (FOS). Two groups of set yoghurts containing no supplement or 2% FOS were manufactured using three different starter cultures to determine the effect of processing, starter culture type, FOS supplementation and storage on CLA content. Processing of milk into yoghurt, the addition of FOS alone and storage for 28 d did not significantly affect CLA isomer formation in yoghurts (P > 0.05). However, significant increases in both isomer formation were obtained by using L. acidophilus or B. animalis in yoghurt manufacture (P < 0.05). The highest increases in c9t11-CLA isomer and total CLA content were found in yoghurts manufactured with L. acidophilus and FOS (2.71-fold increase in total CLA), and B. animalis and FOS (2.90-fold increase in total CLA) (P < 0.05). (c) 2007 Elsevier Ltd. All rights reserved.