Adaptation and optimization of a fluorescence method to determine hydrogen peroxide in rainwater of Ribeirão Preto

• Grant number: 14/02784-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2014
• End date: April 30, 2015
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Maria Lúcia Arruda de Moura Campos
• Grantee: Caroline Scaramboni
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Hydrogen peroxide is one of the most important oxidants present in the troposphere, affecting its oxidative capacity. This substance plays an important role in the oxidation of sulfur dioxide, producing sulfuric acid, which contributes to the rainwater acidification. Moreover, hydrogen peroxide also promotes the oxidation of organic compounds because during its photodegradation there is the formation of hydroxyl radicals, which are extremely reactive. In Brazil, due to the high use of ethanol fuel, species such as alcohols and aldehydes are emitted in high concentrations into the atmosphere, leading to formation of an environment rich in oxygenated organic compounds, especially in large urban centers. Some aldehydes have great relevance to human health. Other members of the research group will quantify species such as ethanol, acetate, formate and sulphate in rainwater, and therefore, the quantification of hydrogen peroxide will be very useful to better understand the mechanisms of production and consumption of these species. The method that uses the oxidation of 2'-7'- dichlorodihydrofluorescein diacetate (DCFH/DA) to quantify hydrogen peroxide has already been developed; however, we have not found records in the literature of its application to environmental samples. Once the method is adapted, we believe that the high sensitivity of the method will enable the quantification of hydrogen peroxide in rainwater with great accuracy and precision. The objectives of this project are: to adapt and optimize a method that uses fluorescence to determine hydrogen peroxide in rainwater; to test a new method for better preservation of the rainwater samples; to evaluate the need of filtering the samples before analysis; and to determine hydrogen peroxide concentration in samples of rainwater of Ribeirão Preto city.