Microbiosensor for Salicylate Based on Modified Carbon Fibre

ABSTRACT

A microbiosensor is proposed for a quick and easy amperometric determination of salicylate. The methodology involves the use of the enzyme salicylate hydroxylase (SH) to convert salicylate to catechol, which is then oxidised at the carbon fibre electrode. The covalent immobilisation of the enzyme onto a carbon fibre electrode via carbodiimide results in an amperometric biosensor with high sensitivity, low detection limit and good stability. The response of the biosensor is linearly proportional to the salicylate concentration between 1.0 10⁻⁷ and 2.0 10⁻⁶ mol L⁻¹, at an applied potential of 300 mV vs SCE, with a response time of 3.5 s and a detection limit of 3.3 10⁻⁸ mol L⁻¹. The relative standard deviation for the determination was 4.1% for n=10. The biosensor was applied to determine salicylate in urine and pharmaceutical samples and compared to the reference method with a good correlation.

Keywords::

• amperometric biosensor
• modified carbon fibre
• salicylate hydroxylase
• modified electrode