Yazar "Güçer, S" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Öğe
    Determination of total and fluoride bound aluminium in tea infusions by ion selective electrode and flame atomic absorption spectrometry
    (Marcel Dekker Inc, 2000) Erdemoglu, SB; Türkdemir, H; Güçer, S
    Speciation of metallic compunds is important especially for their bioavailability. In this present study fluoride bound aluminium species were determined in tea infusion. Total aluminium was measured using name atomic absorption spectrometry (FAAS). Free fluoride and total fluoride were measured by fluoride selective ion electrode (FISE) with the assistance of TISAB buffer solution used for adjustment of pH and total ionic strength, and ALCOA buffer solution which decomposes all of the Al-fluoride complexes in solution. During the studies, the effects of pH and time on the formation of Al-F complexes and interference of some metal ions found in tea infusion such as Al3+, Mg2+, Fe2+, Fe3+ and Mn2+ on the concentration of free fluoride were investigated. The concentration of each Al-fluoride complexes in tea infusion were determined indirectly by calculation using pF-Mole Fraction Diagram. It was found that 1.13+/-0.15 mg l(-1) of 12.00+/-0.86 mg l(-1) total aluminium is fluoride bound aluminium, which means that approximately 10% of total aluminium in tea infusion is complexed with fluoride.
  • Küçük Resim Yok
    Öğe
    Selective determination of aluminum bound with tannin in tea infusion
    (Japan Soc Analytical Chemistry, 2005) Erdemoglu, SB; Güçer, S
    In this study, an analytical method for indirect measurement of Al bound with tannin in tea infusion was studied. This method utilizes the ability of the tannins to precipitate with protein. Separation conditions were investigated using model solutions. This method is uncomplicated, inexpensive and suitable for real samples. About 34% of the total Al in brew extracted from commercially available teas was bound to condensed and hydrolyzable tannins.
  • Küçük Resim Yok
    Öğe
    Speciation of aluminum in tea infusion by ion-exchange resins and flame AAS detection
    (Elsevier Science Bv, 2000) Erdemoglu, SB; Pyrzyniska, K; Güçer, S
    In this study, it was attempted to fractionate aluminum that bound to hydrolyzable polyphenols and its cationic species, and to determine their concentrations in tea infusion by using ion exchange resins and flame AAS detection. In order to separate the hydrolyzable polyphenols bound aluminum species Amberlite XAD-7 resin was used while Chelex-100 resin was used to separate cationic aluminum species. For separation of aluminum species, after the optimization study based on the model solutions, the effluent from column filled with Amberlite XAD-7 was pumped directly through the column filled with Chelex-100 resin. Aluminum in all effluents was determined by FAAS method. It was found that about 30% of aluminum from black tea leafs transfers into the infusion that contains 11-12 mg l(-1) of Al and that about 10-19% of total aluminum in tea infusion is present as cationic species, while about 28-33% of as hydrolyzable polyphenols bound aluminum. (C) 2000 Elsevier Science B.V. All rights reserved.