Dropview 8400

The electrochemical measurements were performed using a μStat 8000 portable potentiostat equipped with DropView 8400 Software (DropSens, Asturias, Spain). Disposable dual screen-printed carbon electrode (DRP-X1110, Dropsens, Oviedo, Spain), consisting of two ellipses-shaped carbon ink working electrodes (6.3 mm² each), a carbon ink counter electrode and a silver pseudo-reference electrode were used as the transducer.
A ThetaLite100 instrument (Biolin Scientific, Finland) was used to analyze the contact angle of the modified electrode. An Axis Ultra spectrometer (Kratos Analytical, Manchester, UK) was used to employ X-ray photoelectron spectroscopy (XPS) analysis with both survey scan and detailed scan by passing 160 eV and 20 eV energy, respectively. The raw data were then interpreted using CasaXPS software (version 2.3.25 PR1.0) with charge correction performed by referring to the hydrocarbon component of the C1s peak at 285.0 eV.

Voltammetric measurements were conducted in a conventional glass cell using an μSTAT 400 potentiostat controlled by DropView 8400 software (DropSens, Oviedo, Spain). A three-electrode setup was used, consisting of a working glassy carbon (GC) electrode with an active surface of 5 mm diameter, a platinum counter electrode and a Ag/AgCl (3 M KCl) reference electrode, chemically isolated from the test solution with a porous Vycor frit (Metrohm Autolab B.V., Utrecht, The Netherlands). A boron-doped diamond (3 mm diameter, BDD, Windsor Scientific Ltd., Slough, UK) and disposable screen-printed carbon paste (SP-CP, model DRP-110, 4 mm diameter, DropSens, Oviedo, Spain) were also used as working electrodes.
The UHPLC system consisted of a 1290 Infinity LC system equipped with an auto-sampler, a degasser, a quaternary pump, a column thermostat and a diode array detector (DAD) operating at 273 nm. A Kinetex XB-C18 2.1 mm × 100 mm, 2.6 μm column (Phenomenex Torrance, CA, USA) was used at room temperature. For the analysis of the chromatograms, LC OpenLab was used. All equipment was purchased from Agilent Technologies (Waldbronn, Germany).

PVC-supported ISE gold working electrode and gold counter electrode of SPGE arranged with Ag/AgCl (3M KCl). Electrochemical cells are as follows:
Ag(s)|AgCl(s)|KCl (3M)||x mM Cd(NO₃)₂(aq)|single plasticized PVC|Au(s) (cell 1)
Ag(s)|AgCl(s)|KCl (3M)||x mM Cd(NO₃)₂(aq)|hybrid plasticized PVC|Au(s) (cell 2)
Ag(s)|AgCl(s)|KCl (3M)||x mM Cd(NO₃)₂ in supporting electrolytes|hybrid plasticized PVC|Au(s) (cell 3)
Ag(s)|AgCl(s)|KCl (3M)||x mM Cd(NO₃)₂ in supporting electrolytes|TBACl/hybrid plasticized PVC|Au(s) (cell 4)
Three-electrode setup was employed with a potentiostat (µstat 400, Metrohm, Zofingen, Switzerland), and cyclic voltammogram was observed with the potential scanning within the from 1.0 to −1.0 V at a scan rate of 0.05 V/s. The current response from the sensor was recorded and visualized using DropView 8400 software (Metrohm, Zofingen, Switzerland). The peak currents (µA) could be observed on the cyclic voltammogram used for standard curve analysis.

EIS evaluation was performed using an electrochemical impedance spectroscope µStat-I 400s (Metrohm Dropsens, Asturias, Spain). Impedance was measured at 25 logarithmically distributed points over a frequency range of [1 Hz–1 MHz] through a 10 mV sinusoidal AC pulse applied between a chopstick-like pair of Ag electrodes (one acting as working electrode and the other as pseudo-reference electrode) placed on the inside and outside of the insert at a fixed distance (Figure 1). Capacitance (C) was calculated as: $$C=\frac{1}{2\pi f{Z}^{″}}$$
where, C is the capacitance, f is the frequency, and Z″ is the imaginary term of impedance. Data were analyzed using DropView 8400 software (Metrohm Dropsens).