Sunday, April 29, 2007

Ethanol analysis with different integrated biosensors systems

Eliana, M. Alhadeff1, Andrea Medeiros Salgado1, Oriol Cós2, Pereira Jr. Nei1, Francisco Valero2, and Valdman Belkis1. (1) Engenharia Bioquímica, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, Centro de Tecnologia, Escola de Química, Bloco E, sala E-203, Rio de Janeiro, Brazil, (2) Enginyieria Química, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain

Different integrated systems working with a bi-enzymatic biosensor with flow injection analysis (FIA) and sequential injection analysis (SIA) methodologies for ethanol detection were developed and applied for extracted ethanol from gasohol mixtures, in alcoholic beverages and in fermented medium, for comparison. The characteristics of the response signal such as repeatability and reproducibility were evaluated for each system and good results were observed. The enzymes alcohol oxidase (AOD) and horseradish peroxidase (HRP) were used with phenol and 4-aminophenazone for ethanol analysis, and the colored product detected with a colorimeter. The enzymes were immobilized separately on glass aminopropyl and packed in two micro reactors. The integrated biosensor FIA system worked with different configurations: (i) one micro reactor packed with immobilized AOD, and injection of free HRP and reagent solution; (ii) two micro reactors and the immobilized enzymes and different strategies for diluting the concentrated ethanol samples (off-line and on-line). One SIA system working with two micro reactors and off-l+ine sample dilutions was proposed. The linear detection range for the FIA system working with two micro reactors, with 1:7000 dilution ratio, was 0.001 – 0.047 g/L. For the integrated biosensor SIA system the linear range was 0.005 - 0.04 g/L.

Keywords: Flow injection analysis, sequential injection analysis, ethanol, alcohol oxidase, horseradish peroxidase, biosensor