Preliminary investigation of iota-carrageenan as an electrode modifier for the voltammetric analysis of Pb (II)

Date

4-2001

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Jose H. Santos

Co-adviser

Nerlissa P Concibido

Abstract

SOLIS, CHRISTINA GEORGINA M. University of the Philippines Los Banos, April 2001. Preliminary Investigation on the Use of Iota-Carrageenan as an Electrode Modifier for the Voltanimetric Analysis of Pb (11).

Adviser: Dr. Jose H. Santos

Iota-carrageenan is known to bind with metals and possesses ion exchange properties. When used as an electrode modifier, it showed high affinity towards Pb (H) in aqueous solutions. To ensure stability of the electrode, the sol gel process was used to encapsulate iota-carrageenan on the electrode surface. The composition of the modifier used throughout the analysis was 20% (w/w) iota-carrageenan - 80% (w/w) graphite powder and a total volume of 450 ttL of the sol solution composed of methyltrimethoxysilane (MTMOS), ethanol and hydrochloric acid. The potential window of iota-carrageenan modified sol gel electrode (i-CarrSGE) ranges from —1000 mV to almost 1500 mV. Differential pulse anodic stripping voltammetry allowed the analysis of standard solutions of Pb (II) in 0.1 M HCI as the supporting electrolyte. Linearity of the relationship between peak current response and Pb (H) concentrations was observed up to 50 ppm giving a detection limit (signal-to-noise ratio of 3) of 0.12 ppm (6.0 x 10 -7 M) and sensitivity of 0.046 p.A per ppm. Consistent with theoretical predictions, increasing the accumulation and deposition times also increased peak current response. Reproducibility of electrode performance was also investigated by randomly selecting ten freshly prepared electrodes and employing the same electrochemical conditions. The relative standard deviation of the peak currents obtained using the electrodes was 53 % suggesting significant differences among the electrodes prepared in a batch. Because of these differences, the use of only one electrode is suggested in the analysis of Pb (II) solutions. Also, further study should be done on how to minimize these deviations.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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