Additively manufactured ready-to-use platform using conductive recycled PLA for ketamine sensing

The use of 3D-printed electrodes is reported fabricated from in-house conductive filament composed of a mixture of recycled poly (lactic acid) (rPLA), graphite (Gpt), and carbon black (CB) for fast detection of the abused drug ketamine. Firstly, the performance of these electrodes was evaluated in comparison to 3D-printed electrodes produced employing a commercially available conductive filament. After a simple pretreatment step (mechanical polishing), the new 3D-printed electrodes presented better performance than the electrodes produced from commercial filament in relation to peak-to-peak separation of the redox probe [Fe(CN)₆]^3-/^4- (130 mV and 759 mV, respectively), charge transfer resistance (R_ct = 1.04 ± 0.05 kΩ and 9.62 ± 0.03 kΩ, respectively), and heterogeneous rate constant (k⁰ = 7.16 ± 0.05 × 10^-3 cm s^-1 and 3.57 ± 0.03 × 10^-3 cm s^-1, respectively). Excellent analytical characteristics for the detection of ketamine were achieved, including wide linear range (10 to 250 μmol L^-1), excellent sensitivity (0.024 ± 0.001 μA μmol L^-1), low limit of detection (LOD = 0.7 μmol L^-1), and recovery values from 82 to 115% for beverage samples (white and red wines, beer, water, and vodka) spiked with the abused drug ketamine.