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Now showing 1 - 10 of 134
  • PublicationMetadata only
    HPLC and LC-MS/MS methods for determination of sodium benzoate and potassium sorbate in food and beverages: Performances of local accredited laboratories via proficiency tests in Turkey
    (2015-05-15T00:00:00Z) Goren, AHMET CEYHAN; BILSEL, Gokhan; SIMSEK, Adnan; BILSEL, Mine; AKCADAG, Fatma; TOPAL, Keyser; OZGEN, Hasan; GÖREN, AHMET CEYHAN
    High Performance Liquid Chromatography LC-UV and LC-MS/MS methods were developed and validated for quantitative analyses of sodium benzoate and potassium sorbate in foods and beverages. HPLC-UV and LC-MS/MS methods were compared for quantitative analyses of sodium benzoate and potassium sorbate in a representative ketchup sample. Optimisation of the methods enabled the chromatographic separation of the analytes in less than 4 min. A correlation coefficient of 0.999 was achieved over the measured calibration range for both compounds and methods (HPLC and LC-MS/MS). The uncertainty values of sodium benzoate and potassium sorbate were found as 0.199 and 0.150 mg/L by HPLC and 0.072 and 0.044 mg/L by LC-MS/MS, respectively.
  • PublicationMetadata only
    Isolation of active constituents from cherry laurel (Laurocerasus officinalis Roem.) leaves through bioassay-guided procedures
    (2012-01-31T00:00:00Z) Akkol, Esra Kupeli; Kirmizibekmez, Hasan; Kucukboyaci, Nurgun; Goren, AHMET CEYHAN; Yesilada, Erdem; GÖREN, AHMET CEYHAN
    Ethnopharmacological relevance: The fresh leaves of Laurocerasus officinalis Roem. (Rosaceae) are externally used against pain and feverish symptoms in Turkish folk medicine.
  • PublicationMetadata only
    Investigation of Anticholinergic, Antidiabetic and Antioxidant Activities of Cinnamon (Cinnamomum Verum) Bark Extracts
  • PublicationMetadata only
    Fatty Acid Methyl Ester Composition of Some Turkish Apiaceae Seed Oils: New Sources for Petroselinic Acid
    (2016-11-01T00:00:00Z) Kucukboyaci, Nurgun; Ayaz, Fatma; Adiguzel, Nezaket; Bani, Baris; Goren, AHMET CEYHAN; GÖREN, AHMET CEYHAN
    The seed oils of twenty-six species of Apiaceae belonging to the genera Bunium, Cnidium, Ferula, Ferulago, Heracleum, Hippomarathrztm, Malabaila, Myrrhoides, Olymposciadium, Pimpinella, Prangos, Szovitsia, Trigonasciadium, Trinia and Zosima, collected in Turkey, were investigated for their oil content, and amount of petroselinic acid (PA), as well as for the composition of their fatty acid methyl esters (FAMEs) by GC-MS. Seed oil content ranged from 7.1% in Szovitsia callicarpa to 29.3% in Ferula haussknechtii. The results showed that the seed oils of the studied species contained high amounts of PA (1.2-72.2%), followed by significant amounts of linoleic (LA, 13.8-50.8%) and oleic (OA, 4.2-61.6%) acids. PA was found in all the analyzed species, except for Olymposciadium caespitosum, which belongs to a monotypic endemic genus of the family. According to data from our study, PA was found to be predominantly in the seed oils of Hippomarathrum cristatum (72.2%), Trinia glauca (64.9%) and Bunium microcarpum (59.7%) and, therefore these species might be considered as new sources of PA, and represent a potential oleochemical raw material. This is the first extensive study of the composition of Turkish Apiaceae species. The high amounts of PA may also have chemotaxonomic significance.
  • PublicationMetadata only
    Potential reference measurement procedures for PBDE in surface water at levels required by the EU Water Frame Directive
    (2016-05-15T00:00:00Z) SWART, Claudia; GANTOIS, Fanny; PETROV, Panayot; ENTWISLE, John; GOENAGA-INFANTE, Heidi; NOUSIAINEN, Marjaana; BILSEL, Mine; BINICI, Burcu; GONZALEZ-GAGO, Adriana; PROEFROCK, Daniel; Goren, AHMET CEYHAN; GÖREN, AHMET CEYHAN
    Polybrominated diphenylethers (PBDE), used as flame retardants, are named as priority substances in the Directive 2000/60/EC of the European parliament and of the council establishing a framework for Community action in the field of water policy. An annual average environmental quality standard (EQS) for inland surface waters of 0.0005 mu g/L (0.0002 mu g/L for other surface waters) for PBDE congeners involved in the technical penta-PBDE mixtures containing PBDE with five bromine atoms has been established. The directives focus especially on the congeners PBDE 28, 47, 99, 100, 153 and 154 contained in the penta-PBDE mixture. Up to now, no reference measurement procedures have been established reaching the limits of quantification (LOQs) and the associated uncertainties as defined in the directives with results traceable to the SI. Within a recent European project on metrology, different approaches for the traceable quantification of PBDE, based on liquid/liquid or solid phase extraction followed by the detection with gas chromatography coupled to either inductively coupled plasma mass spectrometry or triple quadrupole mass spectrometry, were investigated and the related LOQs and expanded uncertainties of the results were compared. A complete uncertainty budget for each method was estimated according to the Guide to the Expression of Uncertainty in Measurement (GUM). All presented analytical procedures can serve as reference measurement procedures regarding the LOQs and their associated expanded uncertainties for monitoring the six priority PBDEs named above. LOQs as low as 0.026 ng/kg with an associated expanded uncertainty of 0.002 ng/kg could be achieved (C) 2016 The Authors. Published by Elsevier B.V.
  • PublicationMetadata only
    CCQM-K132: low-polarity analytes in a biological matrix: vitamin D metabolites in human serum
    (2017-01-01T00:00:00Z) Wise, Stephen A.; Tai, Susan S-C; Duewer, David L.; Bedner, Mary; Camara, Johanna E.; Lippa, Katrice A.; Qinde, Liu; Kang, Dukjin; Kim, Byungjoo; Quan, Can; GÖREN, AHMET CEYHAN
  • PublicationMetadata only
    Sambulin A and B, non-glycosidic iridoids from Sambucus ebulus, exert significant in vitro anti-inflammatory activity in LPS-induced RAW 264.7 macrophages via inhibition of MAPKs-s phosphorylation
    (2017-07-12T00:00:00Z) Balkan, Irem Atay; Akulke, Ayca Zeynep Ilter; Bagatur, Yesim; Telci, Dilek; Goren, AHMET CEYHAN; Kirmizibekmez, Hasan; Yesilada, Erdem; GÖREN, AHMET CEYHAN
    Ethnopharmacological relevance: The leaves of Sambucus ebulus L. (Adoxaceae) are widely used in Turkish folk medicine particularly against inflammatory disorders. The fresh leaves after wilted over fire or the poultices prepared are directly applied externally to heal burns, edema, eczema, urticarial and abscess. Two iridoids were recently isolated (sambulin A, sambulin B) from the leaves of S. ebulus.
  • PublicationOpen Access
    Antidiabetic, anticholinergic and antioxidant activities of aerial parts of shaggy bindweed (Convulvulus betonicifolia Miller subsp.) - profiling of phenolic compounds by LC-HRMS
    (2021-05-01T00:00:00Z) Bingol, Zeynebe; Kızıltaş, Hatice; GÖREN, AHMET CEYHAN; Kose, Leyla Polat; Topal, Meryem; DURMAZ, LOKMAN; Gulcin, İlhami; Alwasel, Saleh H.; GÖREN, AHMET CEYHAN
    In order to evaluate the antioxidant activity of evaporated ethanolic extract (EESB) and lyophilized water extract (WESB) of Shaggy bindweed (Convulvulus betonicifolia Mill. Subs), some putative antioxidant methods such as DPPH. scavenging activity, ABTS(center dot)(-) scavenging effect, ferric ions (Fe3+) reduction method, cupric ions (Cu2+) reducing capacity, and ferrous ions (Fe2+) binding activities were separately performed. Also, ascorbic acid, alpha-tocopherol and BHT were used as the standard compounds. Additionally, some phenolic compounds that responsible for antioxidant abilities of EESB and WESB were screened by liquid chromatography-high resolution mass spectrometry (LC-HRMS). At the same concentration, EESB and WESB demonstrated effective antioxidant abilities when compared to standards. In addition, EESB demonstrated IC50 values of 1.946 mu g/mL against acetylcholinesterase (AChE), 0.815 mu g/mL against alpha-glycosidase and 0.675 mu g/mL against alpha-amylase enzymes.
  • PublicationMetadata only
    Analysis of Combustion Stability and Its Relation to Performance Characteristics in a Compression Ignition Engine Fueled with Diesel-biodiesel Blends
    (2011-01-01T00:00:00Z) CEVİZ, Münacettin; Koncuk, F.; Kucuk, O.; Goren, AHMET CEYHAN; Yuksel, F.; GÖREN, AHMET CEYHAN
    This article investigates the effects of using diesel-biodiesel blends on compression ignition engine performance characteristics. Combustion stability observed from in-cylinder pressure related parameters, biodiesel composition, and the fuel properties of the blends are used to analyze the variations of the characteristics. Making biodiesel from hazelnut oil is done by esterification and then experiments are conducted with the neat diesel and diesel-biodiesel blends in a four stroke naturally aspirated direct injection diesel engine. Volumetric blending ratios of biodiesel with no. 1 diesel were set at 0, 20, 40, 60, 80, and 100. It has been found that, in general, the hazel nut oil-based biodiesels behave comparably to the diesel fuel in terms of engine performance characteristics. There is no significant brake torque and power reduction, and there is a slight increase in brake specific fuel consumption when the engine is operated with diesel-biodiesel blends. The engine effective efficiency shows improvements as compared to that of the diesel fuel operating under similar conditions, especially at low blending ratios of biodiesel. The engine performance characteristics and exhaust emissions improve remarkably at B20 operations and identifying the mechanism for biodiesel blending effects is attempted.
  • PublicationMetadata only
    Final Report on Key Comparison CCQM-K55.c (L-(+)-Valine): Characterization of Organic Substances for Chemical Purity
    (2014-01-01T00:00:00Z) Westwood, Steven; Josephs, Ralf; Choteau, Tiphaine; Daireaux, Adeline; Wielgosz, Robert; Davies, Stephen; Moawad, Michael; Chan, Benjamin; Munoz, Amalia; Conneely, Patrick; Ricci, Marina; Pires do Rego, Eliane Cristina; Garrido, Bruno C.; Violante, Fernando G. M.; Windust, Anthony; Dai, Xinhua; Huang, Ting; Zhang, Wei; Su, Fuhai; Quan, Can; Wang, Haifeng; Lo, Man-fung; Wong, Wai-fun; Gantois, Fanny; Lalerle, Beatrice; Dorgerloh, Ute; Koch, Matthias; Klyk-Seitz, Urszula-Anna; Pfeifer, Dietmar; Philipp, Rosemarie; Piechotta, Christian; Recknagel, Sebastian; Rothe, Robert; Yamazaki, Taichi; Bin Zakaria, Osman; Castro, E.; Balderas, M.; Gonzalez, N.; Salazar, C.; Regalado, L.; Valle, E.; Rodriguez, L.; Angel Laguna, L.; Ramirez, P.; Avila, M.; Ibarra, J.; Valle, L.; Perez, M.; Arce, M.; Mitani, Y.; Konopelko, L.; Krylov, A.; Lopushanskaya, E.; Lin, Teo Tang; Liu, Qinde; Kooi, Lee Tong; Fernandes-Whaley, Maria; Prevoo-Franzsen, Desiree; Nhlapo, Nontete; Visser, Ria; Kim, Byungjoo; Lee, Hwashim; Kankaew, Pornhatai; Pookrod, Preeyaporn; Sudsiri, Nittaya; Shearman, Kittiya; Goren, Ahmet Ceyhan; Bilsel, Gokhan; Yilmaz, Hasibe; Bilsel, Mine; Cergel, Muhiddin; Coskun, Fatma Gonca; Uysal, Emrah; Gunduz, Simay; Un, Ilker; Warren, John; Bearden, Daniel W.; Bedner, Mary; Duewer, David L.; Lang, Brian E.; Lippa, Katrice A.; Schantz, Michele M.; Sieber, John R.; GÖREN, AHMET CEYHAN