&&ReWrAp:HEADERFOOTER:0:ReWrAp&&

Date of Award

Fall 2013

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Chemical Engineering

Supervisor

Robert Pelton

Co-Supervisor

Carlos Filipe

Language

English

Abstract

Research in paper-based analytical devices has been increasing in recent years. Before technology transfer and market acceptance, these paper-based sensors have to be validated with field samples. In this study, we have made an attempt to evaluate the effectiveness of paper-based sensors to detect pesticides in real world samples. Generation 1 biosensor has been modified to be user friendly. There is no difference in the performance of generation 2 sensors; they detect pesticides based on colorimetric assay. The assay protocol involves first introducing the sample to the sensing zone by pipetting the water sample. Following an incubation period of 15min, the substrate end of the sensor is dipped into the sample to move paper bound indoxyl acetate (IDA) to the sensing region to initiate the enzyme-catalyzed hydrolysis of the substrate, resulting in the development of blue color. The presence of pesticide is indicated by either a decrease in color intensity or with no color development at all.

To evaluate the effectiveness of biosensor in detecting pesticides in real world samples, a field study was conducted in four villages of southern India. Water samples from different aquatic environment including both surface water and ground water, were tested using generation 2 paper-based sensors. The paper-based sensors were capable of detecting organophosphorus pesticides in real world samples. The results were confirmed using GC-MS.

The presence of higher concentration of dibutyl phthalate (in the range of 100uM to 10mM) in water can be a potential interference for the paper-based assay for the detection of pesticides in water. The paper-based biosensor assay platform can detect pesticides in the environmental samples and results have been validated by GC-MS. But for transfer of technology to the industry, further optimization is required to improve the stability of substrate to withstand atmospheric temperature fluctuations thus allowing the storage and shipment of the biosensor strips. Additionally to conduct reliable assays and obtain consistent results, the fabrication of biosensor strips needs to be improved to maintain the consistent volumes of bioinks impregnated on paper support.

McMaster University Library