As we wanted to develop a cheap method, we did not perform chemical modifications at our
electrodes or treatments at our analytical cell, in contrast with literature reports.
First, we tested the glassy-carbon as the working electrode. This carbon arrangement
provides a surface that acts as a conductor to charge changes. We performed measures using water as the cell
solvent and tested three different buffers: sodium acetate, ammonium nitrate and phosphate-buffered saline
(PBS). These three buffers maintained pH at 4, 9.5 and 6.8 respectively. pH variations alters the interactions
between copper ions and glyphosate. Also, we tested the addition of KCl 3M as the supporting electrolyte. The
tests were conducted with three different methods: Squared-wave, Cyclical and Pulsed voltammetry. Glyphosate
was added at 20 µL drops from a solution of 5000 ppb.
For all tested conditions and possibilities, the results stayed the same: we did observe
changes in electrical current in response to voltage, however, these ups and downs were not analytical. For
example, the same sample did not produced the same variation, or the variation was not bigger than copper
addition at the beginning of our tests. As a result of this experiment, we conclude that this system cannot be
used in this way.
We also tried to repeat the measures using different working electrodes as it follows:
carbon-ink 3D printed, carbon nanotubes 3D printed, copper wires, and golden particles.
For all the possible combinations, our results remained the same: no analytical data could
be observed.
Fig. 1- Overall measures. Measures performed on glassy-carbon electrode, with addition of
KCl 3M on Squared-Wave mode. Glyphosate was added as volume from 5000 ppm solution as indicated
Fig. 2- Detail. Detail from measure of 60 microliters of glyphosate from previoues rsultes.
As denoted, duplicate samples did not performed the same measure, which was observed in all tests
Fig. 3- Overall measures. Measures performed on glassy-carbon electrode, with addition of
KCl 3M on Pulsed mode. Glyphosate was added as volume from 5000 ppm solution as indicated
Fig. 4- Detail. Detail from measure of 20 microliters of glyphosate from previoues rsultes.
As denoted, duplicate samples did not performed the same measure, which was observed in all tests