Preliminary investigation on the Yeast Modified Carbon Paste Electrode (YMCPE) for the determination of ethanol in solution

Date

4-2002

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Norma N. Fajardo

Co-adviser

Norriel S. Nipales

Committee Member

Marivic S. Lacsamana

Abstract

A biosensor for the detection of ethanol was developed. It was constructed by incorporating dry yeast cells in a carbon paste matrix. The dry yeast cells contain the enzyme alcohol dehydrogenase and NAD- needed to enzymatically oxidize the ethanol to acetaldehyde. Differential pulse voltammetric measurement was employed in order to evaluate the response of the yeast-modified carbon paste electrode (YMCPE) to ethanol in solution. A peak at about -0.48 V vs Ag/AgCI was observed, indicating that the YMCPE was responsive to ethanol. A linear response to ethanol concentrations was obtained in the range 0.010 to 0.030 M ethanol giving a correlation coefficient of 0.9869. The response of the different YMCPE's that differ in electrode composition was also investigated. Current peak increased as the amount of yeast was increased from 0 to 20% then dropped as the amount of yeast was further increased from 25 to 30%. The electrode response with and without surface renewal was also studied. The polished electrode showed a lower rate of decrease in peak current (△slope. -1.861µA) compared to the unpolished electrode current △slope, = -1.448pA). The mediator hexacyanoferrate (111) was found to have no effect on the response of the YMCPE.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2002 C4 H47

Document Type

Thesis

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