Drp 150

Experiments were carried out with a computer controlled PalmSens potentiostat. All electrochemical data were collected and analysed by the PalmSens PSTrace software. The electrochemical cell was purchased from Dropsens and consisted of a plexiglass flow cell and a disposable screen ink-printed platinum electrode (SPPtE, DRP-150, Dropsens, Italy). They consisted in a platinum disk-shaped (12.6 mm²) working electrode, a paste of silver/silver chloride pseudo-reference and a platinum strip counter electrode, on a ceramic substrate (3.3 cm × 1.0 cm). All the electrochemical measurements were referred to the screen-printed silver pseudo-reference electrode. The screen printed electrodes were interfaced to the potentiostat by a cable connector for SPEs (DRP-CAC, Dropsens, Italy). A Gilson MiniPuls 3 peristaltic pump and a Rheodyne low pressure injector with a 200-µL sample loop completed the apparatus.

The chemosensors were evaluated by constant-potential amperometry in a three-electrode configuration with an Ag/AgCl reference electrode, a Pt-wire counter electrode, and working electrodes—the 3.05 mm diameter carbon rod (type RW001, Ringsdorff Werke, Bonn, Germany) sealed in a glass tube using epoxy glue, the 4 mm planar carbon electrode DRP-150, and the planar gold electrode DRP-C220AT from DropSens [Llanera (Asturias), Spain].
Platinized electrodes were prepared by electrochemical Pt deposition from a 2% solution of H₂PtCl₆ according to [28 ]. Calibration was performed by stepwise addition of a standard FA solution.

Amperometric measurements were carried out with a portable BiPotentiostat/Galvanostat μStat 400 from Dropsens (Oviedo, Spain) connected via a Cable Connector (Dropsens, CAST) to Screen-Printed Carbon Electrodes (SPCEs) (Dropsens, DRP-150). The SPCEs include a carbon working electrode (4 mm diameter), a silver pseudo-reference electrode and a carbon counter electrode. The SPCEs were placed in a methacrylate cell (Dropsens, CFLWCL-CONIC) that hold the samples extract on the surface. The supplied DropView 8400 software for Windows was used to control the instrument, plot measurements and perform the analysis of results.