"Voltammetric study of papaya latex modified carbon paste electrode (PalaMCPE) for Hg (II) determinations"

Date

4-2000

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Jose H. Santos

Co-adviser

Eugenia M. Castillo

Committee Member

Maxima E. Flavier

Abstract

A voltammetric study of carbon paste modified with papaya latex was carried out for the determination of Hg(II). In aqueous solution, Hg(II) ions were concentrated on the electrode on the basis of its interaction, possibly by complexation, with several functionalities of the latex components with emphasis on reaction with sulfhydryl groups in 0.1 mol neutral (KCI) solution. Reduction of Hg(II) at —0.2 V versus Ag/AgCI effected a reoxidation wave of Hg(0) at 0.00 V on scanning the potential in the positive direction in 0.1 mol NaOH solution by differential pulse technique. A shift in oxidation potential was observed and attributed to a possible contamination and mechanical strain on the reference electrode used. Such circumstance was dealt with by normalization of the potential ranges. Based on measurements of the blank, the detection limit of Hg(II) was observed to be 1.45 11M when the accumulation time was 2 minutes at a deposition potential of —0.22 V and deposition time of 1.5 minutes. This value is lower than the reported 2.49 LIM and 0.50 mM for normal AAS and FES, respectively. Best composition was found to comprise 20 mg latex and 80 mg carbon powder in 30 AL mineral oil. Effects of pH, preconcentration time, deposition time, and Hg(II) concentration were evaluated. Investigation on the applicability of Rhizopus delemar lipase as a modifying agent was likewise carried out.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2000 C4 M33

Document Type

Thesis

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