Preliminary investigation on the Lipase-Modified Polyaniline Pencil pH Electrode (LMPAniE) for the determination of lipids in solution

Date

4-2003

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Norriel S Nipales

Co-adviser

Eugenia M. Castillo

Abstract

ABSTRACT

NAVARRO, DIVINA ANGELA G. College of Arts and Sciences. University of the Philippines Los Barns. April 2003. "Preliminary Investigation on the Lipase-Modified Polyaniline Pencil Electrode (LMPAniPE) for the Determination of Lipids in Solution"

Adviser: Dr. Norriel S. Nipales

A Lipase-modified Polyaniline Pencil electrode was fabricated for the determination of lipids in solution. Preliminary investigations were performed in the determination of a functional lipase electrode. Electrodes were constructed based on a Rhizopus delemar lipase and a pencil lead modified with polyaniline by electropolymerization. The electrode that showed response to lipids, in the form of coconut oil solutions, was the lipase-modified electrode, which comprises of a polyaniline modified pencil immersed in water contained in a pipette by with a lipase plug, designated as electrode E2A. Responses were based on the hydrolysis of lipids that takes place in the presence of lipase. Using this electrode, plots with positive slopes and good linearibes were obtained for the survey potential (in mV) against different oil concentrations, with an equilibration time of 5 minutes. Further analysis showed that use of lipase immobilized in silica gel in the electrode construction would produce electrodes, designated as E2B, with better responses than that of electrodes utilizing pure lipase. This electrode has an equilibration time of 10 minutes.

After determining the responses of electrodes E2A and E2B to different oil concentrations, reusability of these electrodes were also studied. Results showed that for electrode E2A, reuse has a positive effect on its sensitivity, increasing its slope by almost 145%. This was attributed to the priming up of the enzyme activity upon reuse. For electrode E2B, reuse resulted in the depreciation of electrode response, decreasing its slope by almost 145%. This was attributed to the decreasing enzyme concentration in the electrode, which limits the activity of the enzyme, upon reuse. For these electrodes, longer equilibration times were observed.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2003 C4 N38

Document Type

Thesis

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