Sensors & Transducers Journal
(ISSN 1726- 5479)
Vol. 76, Issue 2, February 2007, pp. 978-990
A Simple and Sensitive Flow Injection Optical Fibre Biosensor Based on Immobilised Enzyme for Monitoring of Pesticides
B. Kuswandi* and N. W. Suwandari
School of Pharmacy, University of Jember, Jember 68121 Indonesia,
Received: 3 January 2007 / Accepted: 22 February 2007 / Published: 26 February 2007
Abstract: A simple and sensitive flow injection optical fibre biosensor based on immobilised enzyme for monitoring of pesticides has been developed. The optical fibre biosensor consists of immobilised acethylcholinesterase (AChE) coupled with commercial pH indicator strip. The biosensing process involves the inhibition of AChE by pesticides, where the pH change has been monitored via a pH indicator strip as an optical transducer. The enzyme as a bio-recognition element has been immobilised onto solid-support material (i.e. covalently bond onto preactivated isothiocyanate glass, ICG) and then packed in a thermostatic bioreactor connected to the flow-cell that contains pH indicator strip. In the presence of a constant AChE, a colour of the pH layer change and the measured reflected signal could be related to the pesticide concentration in the sample solution. The performance of the flow injection optical biosensor system has been optimized, including chemical and physical parameters. The calibration plot of the inhibition for the determination of organophosphate pesticides (dimethoate) and carbamate pesticide (propoxur) were in the range of 50 to 1000 µg/l for dimethoate and 10 to 100 µg/l for propoxur. The biosensor allows lower detection limits, calculated at I10%, for propoxur (4.9 µg/l) than for dimethoate (24 µg/l), and produces highly reproducible response (RSD<1.5%) and readily reversible in the case of carbamate pesticide. While in the case of organophosphate, the regeneration has been possible by treatment with hydroxylamine solution. The flow injection optical fibre biosensor system has been successfully applied for the determination of pesticides in the real water samples.
Keywords: Optical fibre biosensor, immobilised enzyme, pH indicator strip, pesticides
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