Fabrication of an NO2- selective modified pH probe for the analysis of NO2 in aquatic systems

Janet V. Neri

Date

5-1993

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Aloysius U. Baes

Abstract

ABSTRACT

NERI, JANET VILLAMORA. College of Arts and Sciences, University of the Philippines Los Banos, May 1993. Fabrication of a Nitrogen Dioxide-Selective Modified pH Probe for the Analysis of NO2 in Aquatic Systems.

Adviser: Dr. Aloysius U. Baes

Nitrite in water samples can be satisfactorily determined using an NO2-selective probe. A modification of a pH glass electrode was made to design an NO2-selective probe. Coupled with a reference electrode, the NO2 probe was characterized for its Nernstian response, response time and stability. The electrode exhibited a good Nernstian response. The potential in mV plotted against NO2 concentration resulted in a straight line with a slope of about 60 mV per decade when using a PTFE or a Teflon membrane over a concentration range of 10-6 to 10-2 M NO2.

The electrode exhibited faster response at high determinant concentrations, becoming more and more sluggish as the limit of detection is approached of about 10-7 M. The response time for NO2 concentrations of 10-6 to 10-5 M was observed to be within five minutes. Above these concentrations, response times were observed to be within three minutes.

Water samples were analyzed for nitrite content using the NO2 probe and results were consequently compared with that of the standard colorimetric method for nitrite analysis. The results obtained using the nitrite probe was not statistically different from the standard colorimetric method. The electrode method of analysis is simple, rapid and precise, and its results are not affected by color or turbidity present in samples under analysis.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 1993 C4 N47

Document Type

Thesis

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