Silver materials are known to present excellent properties, such as high electrical and thermal conductivity as well as chemical stability. Silver-based inks have drawn a lot of attention for being compatible with various substrates, which can be used in the production uniform and stable pseudo-reference electrodes with low curing temperatures. Furthermore, the interest in the use of disposable electrodes has been increasing due to the low cost and the possibility of their use in point-of-care and point-of-need situations. Thus, in this work, two new inks were developed using Ag as conductive material and colorless polymers (nail polish (NP) and shellac (SL)), and applied to different substrates (screen-printed electrodes, acetate sheets, and 3D-printed electrodes) to verify the performance of the proposed inks. Measurements attained with open circuit potential (OCP) attested to the stability of the potential of the pseudo-reference proposed for 1 h. Analytical curves for β-estradiol were also obtained using the devices prepared with the proposed inks as pseudo-references electrodes, which presented satisfactory results concerning the potential stability (RSD < 2.6%). These inks are simple to prepare and present great alternatives for the development of pseudo-reference electrodes useful in the construction of disposable electrochemical systems.

Extrusion-based three-dimensional (3D) printing is a promising technology for the construction of electrochemical devices and some features can be highlighted such as low-cost, versatility, large-scale production, fast prototyping in varied designs and availability of conductive filaments. Herein, we show the detection of chloramphenicol (CAP) in milk and tap water samples using carbon-black integrated polylactic acid (CB/PLA) electrodes fabricated by combining a 3D pen and 3D-printed substrates. The electrode surface activated in basic medium provided a considerable improvement of CAP response (12-fold) due to the removal of PLA and consequent higher exposure of conductive sites. Differential-pulse voltammetric measurements exploring the reduction of the nitro group of CAP at −0.45 V ( vs. Ag∣AgCl∣KCl _(sat.) ) were performed. A wide linear range (10–331 μ mol L ⁻¹ , r = 0.998) with a detection limit of 0.98 μ mol L ⁻¹ was obtained with a precision of 5.1% (n = 10). Tap water and milk samples were spiked with known amounts of CAP and analyzed by the standard-addition method. Recovery values between 88–93% demonstrated that sample matrix did not interfere on the CAP determination. Therefore, this work shows a promising tool for low-cost construction of electrodes for CAP detection in food and environmental samples which can be extended to other antibiotics.