Ferreira, V. S.Zanoni, Maria Valnice Boldrin [UNESP]Fogg, A. G.2014-05-202014-05-201999-03-29Analytica Chimica Acta. Amsterdam: Elsevier B.V., v. 384, n. 2, p. 159-166, 1999.0003-2670http://hdl.handle.net/11449/32244Ceftazidime is hydrolysed only slowly at pH 10 at room temperature. This is indicated by a small cathodic stripping voltammetric peak obtained at pH 10 at a hanging mercury drop electrode at about -0.6 V which corresponds to the reduction of the hydrolysis product. This peak is enhanced more than tenfold by the addition of poly-L-lysine (PLL) to the electrolyte solution. The optimum accumulation potential is between 0 and -0.1 V: the size of the peak decreases steadily, however, as the accumulation potential is moved to more negative potentials and is about one-sixth the size for accumulation at -0.4 V. Existing knowledge of the organic chemistry of cephalosporins indicates that the accumulation must involve an aminolysis reaction of the unprotonated PLL with the beta-lactam ring of the ceftazidime. The limit of detection (3 sigma) in standard solutions was calculated to be 1 x 10(-10) mol l(-1). The detection limit in buffer solution containing 1% of urine was calculated to be 5 x 10(-9) mol l(-1), i.e. 5 x 10(-6) mol l(-1) in the urine. (C) 1999 Elsevier B.V. B.V. AU rights reserved.159-166engceftazidimecathodic stripping voltammetrypoly-L-lysine modified hanging mercury drop electrodereactive accumulationaminolysisurineArtigo10.1016/S0003-2670(98)00813-7WOS:000079292000006Acesso restrito0000-0002-2296-1393