Construção e avaliação de biossensor amperometrico para salicilato usando salicilato hidroxilase imobilizada em matriz de polipirrol com glutaraldeido

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

This thesis describes the construction of a biosensor for the salicylate determination in blood serum, based on the enzyme salicylate hydroxylase (EC 1.14.13.1), which was electrochemically immobilized onto a polypyrrole polymeric support with glutaraldehyde, to improve the biosensor lifetime, employing a glassy carbon-working electrode as sensor base. The hexacyanoferrate (II) was also incorporated to work as a redox mediator to minimize possible interferences. The salicylate is enzymatically converted to catechol, which is monitored amperometrically at + 0.170 V vs. SCE (saturated calomel electrode). Salicylate determination was carried out using a ratio between b-NADH and salicylate of 4:1 (at 30 °C). The amperometric response of the biosensor was linearly proportional to the salicylate concentration between 2.3 10 and 1.4 10 mol L, in 0.1 mol L phosphate buffer (pH=7.8), containing 0.1 mol L KCl and 5.0 10 mol L Na2H2Y, as supporting electrolyte. Blood serum samples analyzed by this biosensor showed a good correlation compared to the spectrophotometric method (Trinder) used as reference, presenting relative deviations lower than 7.0 %. The recovery studies, in presence of several interfering compounds, showed recoveries between 96.4 and 104.8 %, except to gentisic (108.4 %) and L-ascorbic (93.7 %) acids. The biosensor response time was 16 s in the concentration range evaluated, with 40 days of useful lifetime, using it continuously.

ASSUNTO(S)

acido salicilico quimica analitica cinetica de enzimas

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