Fabrication Of An Electronic Nose And Its Application For The Verification Of Eurycoma Longifolia Extracts
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Date
2007-01
Authors
Islam, Akm Shafiqul
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
An electronic nose based on a quartz crystal microbalance array sensor using ethyl
cellulose (EC), lipids «dioetyl phosphate (DOP). triaetyl methyl ammonium chloride
(TOMA), oleyl amine (OAm» and gas chromatography (GC) stationary phase materials
«ApiezonL (APZ-L), polypropylene glycol 1200 (PPG 1200), polyethylene glyeol1000
(PEG 1000), polyethylene glycol 4000 (PEG 4000). poly(biscyanopropyl-sUoxane) (OV-
275) and diethylene glycol succinate (OEGS» as sensing membrane for the analysis of
extracts of Eurycoma /ongifoJia {Tongkat Ali) was developed. The sensors were
prepared using drop, spin and ultrasonic spray coating methods. Ethyl cellulose-based
sensor was prepared using the drop and spin coating methods while lipids and GC
stationary phase materials were coated using spin and ultrasonic spray coating
methods. Ge stationary phase materials coated by the ultrasonic spray coating method
produce better quality sensors than the spin coating methods.
The reproducibility, sensitivity and detection limits of the sensors towards various
organic volatiles (VOCs) were studied. The array sensor exhibited different sensitivities
towards non-polar and polar volatiles. The highest sensitivity was found towards
butanol vapor [140.7 HzI(gfm3)] for TOMA-based sensor. The detection limit of the
array sensor is at the ppm level. The transient parameters extracted from the response
curves that arises from the adsorption and desorption properties of the sensing
materials and volatiles were also investigated. Transient response curves of the sensor
on exposure to methanol, ethanol. chloroform, acetone and benzene were studied.
Transient parameters, viz., simple parameters consisting of peak heights, derivatives,
slopes and integrals, and polynomial parameters consisting of coefficients from the curve fitting equations, were extracted from the transient response curves and used as
data for the subsequent cnernornetric data analysis. The sensor showed good
separation and classification of the VOCs.
Description
Keywords
Chemistry