Fast chromatographic determination of polycyclic aromatic hydrocarbons in aerosol samples from sugar cane burning |
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Authors: | Godoi Ana F L Ravindra Khaiwal Godoi Ricardo H M Andrade Sandro J Santiago-Silva Mary Van Vaeck Luc Van Grieken René |
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Institution: | Department of Chemistry, Micro- and Trace Analysis Center, University of Antwerp (UA), Universiteitsplein 1, B-2610 Antwerp, Belgium. agodoi@uia.ua.ac.be |
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Abstract: | The influence of the pH on the complexation equilibria between (S)- or (R)-alprenolol and the cellulase Cel7A was investigated by isothermal titration calorimetry. The results obtained agree with those of previous, similar studies of the same equilibria in which the protein was immobilized on silica particles, packed in a chromatographic column. The association constant and the complexation enthalpy and entropy of the (S)-enantiomer increase with increasing pH. For (R)-alprenolol, the binding is endothermic at all pH values. Thus, for both enantiomers in the pH range 5.5-6.8, the binding is an entropically driven process. |
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