IJUP08 - Universidade do Porto

Development of a multicommutated flow system for
chemiluminometric quantification of gentamicin
L. Santos 1 , A. Araújo 1 , A. Fachini 1 , M. Montenegro 1 , B.F. Reis 2
1 REQUIMTE, Department of Physical Chemistry, Faculty of Pharmacy, University of Porto, R.
Aníbal Cunha, 4050 Porto, Portugal.
2 Centro de Energia Nuclear na Agricultura, Universidade de S. Paulo, PO Box 96, 13400-970,
Piracicaba- SP
Multicommutation is a continuous flow system technique that presents several advantages
relatively to flow injection analysis (FIA), such as versatility, low reagent consumption,
and robustness [1].
Chemiluminescence is a high sensitivity methodology, with low detection limits that
requires simple instrumentation. It is based on intensity measurements of light produced in
chemiluminescent reaction. The signal intensity can be correlated with the concentration of
any of the starting reagents. This analytical technique allows the quantification of a wide
variety of compounds that are directly or indirectly involved in the chemiluminometric
reaction [2].
The aim of this work is to quantify gentamicin in different matrices using a
multicommutated flow system where the chemiluminometric oxidation of luminol by
hypochlorite is accomplished. In the presence of gentamicin, an aminoglycoside antibiotic
that is effective against a wide variety of gram-positive and gram-negative bacteria, the
hypochlorite concentration is reduced since it oxidizes the secondary amines presents in
the chemical structure of the analyte.
The optimization process had been separeted in two parts: optimization of chemical
conditions and optimization of flow conditions. In the first part, parameters such as the
hypochlorite and luminol concentrations and the pH of the buffer solution used to prepare
these reagents have being studied. After that, the flow conditions will be tested. In the
final, the proposed method will be applied to the quantification of gentamicin in
pharmaceutical formulations and foodstuffs.
References:
[1] Lavorante, A.F., Feres, M.A. and Reis, B.F. (2006), Multi-commutation in Flow Analysis: A
Versatile Tool for the Development of the Automatic Analytical Procedure Focused on the
Reduction of Reagent Consumption, Spectroscopy Letters, 39 (6), 631-650.
[2] García-Campaña, A.M. and Baeyens, W.R.G. (2000), Principles and recent analytical
applications of chemiluminescence, Analusis, 28 (8), 686-698.
Acknowledgements:
L. Santos thanks to Fundação Astrazeneca the master degree scholarship conceded.
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