Voltammetric Determination of Cisteine by Carbon Paste Electrode Cu-Hg Amalgamated

Tuesday, 7 October 2014
Expo Center, 1st Floor, Center and Right Foyers (Moon Palace Resort)
M. Molina (Universidad Autónoma del Estado de México), P. O. Gil (Instituto Tecnológico de Toluca), G. Roa (Universidad Autónoma del Estado de México), G. Macedo (Instituto Tecnológico de Toluca), and P. Balderas (Centro Conjunto de Investigación en Química Sustentable (CCIQS) UAEM-UNAM)
Plants have a defense mechanism for dealing with heavy metals, so that they are produced rapidly due to the high toxicity of the heavy metals. By this plant defense mechanism occurs, phytochelatins which are polypeptides , wherein a glutamic acid is linked to a cysteine via a γ - peptide bond, so that they have an ability to form bonds with metals through group SH in the portion of the cysteine .

So it is very important find cheap and easily applied for the determination of phytochelatins methods. In literature are reported reported to an amalgam of Cu-Hg was efficient for determining phytochelatins by complexation of Cu+ with thiol groups by electrochemical methods such as voltammetry and polarography cathodic stripping voltammetry, [1].

So in this work is to obtain a carbon paste electrode (CPE) modified with a Cu-Hg amalgam by electrolysis to develop a methodology for the determination of cysteine .

The solutions used to obtain copper and mercury amalgam was a 0.05M concentration by applying a potential of -0.8V. Amalgam characterization was performed by cyclic voltammetry , wherein the support electrolyte was a borate buffer of pH 8.1 0.05M in which electrochemical processes typical Cu oxidation and ensuring Hg amalgam was performed properly observed .

Subsequently technique cathodic stripping voltammetry (SCV) used for applying different potentials cysteine reservoir (Ed -0.28V) for 300 s and a potential sweep -0.1V to -1.0V. The graphics shows a reduction peak at -520mV associated Cu complex formation of cysteine-SR.

The technique has been applied so far has proven to be very efficient since according to literature marked the peak potential is reported in the literature.

This technique can be used as is relatively easy to perform and the data shown are very sensitive to very small quantities, although this technique is still used to determine concentrations of cysteine smaller. For later use it with a real sample in the determination of phytochelatins in mosses.

Works cited

[1]        Y. B., S. I. y N. L., «Voltammetric determination of phytochelatins using Copper solid amalgam electrode,» Talanta, pp. 1253-1258, 2003.