Employment of copper alloys for the direct detection of amino acids in ion chromatography

Author(s)

Victor Costa Bassetto

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2014-07-30

Examining board members

Lauro Tatsuo Kubota; Mauro Bertotti; Juliano Alves Bonacin

• Advisor: Lauro Tatsuo Kubota

Abstract

This dissertation presents the developments made for the application of copper alloys as detector for amino acids in ion chromatography. The work presents the development from fundamental electrochemistry studies, where properties of metals such as gold, current standard for the technique, and copper where tested against amino acids were performed through cyclic voltammetry technique. This method was chosen for the investigation because it allowed exploring the various phenomena that occur in the oxide reduction processes of the molecules on the electrodes. As a feature of the working electrolyte must also be the mobile phase of the chromatography, where 0.15 mol L-1 sodium hydroxide was used. After understanding the basic mechanisms of reduction and oxidation of the different amino acids over gold and copper electrodes in an alkaline medium, the knowledge obtained was transferred to the flow cells. At this time it was observed that the pure copper did not present sufficient resistance to corrosion, limiting its application in ion chromatography system. Thus, we chose the application of brass as sensor material. The chosen brass had 86% copper in its composition and demonstration through the studies, which its redox behavior of the amino acids is similar to those observed on pure copper, but with advantages in corrosion resistance. In addition, copper substrates showing the SERS effect was also developed in conjunction with the University of Southampton. This study was conducted to allow the investigation of intermediary species that are formed between the amino acid and copper (II) on the electrode surface. For application in flow was necessary to develop potential pulses to enable the detection of amino acids and increase the lifetime of the electrode. After the development of the pulses, it was optimized and the system was used for detection of valine in samples of food supplement (AU)

• FAPESP's process: 11/04043-0 - Use of copper alloys for electrochemical detector of amino acids in ion chromatography.
• Grantee: Victor Costa Bassetto
• Support Opportunities: Scholarships in Brazil - Master