A versatile user-friendly electrochemical cell with three 3D-pen-printed electrodes in a tiny micropipette tip

This work describes a practical, portable and versatile electrochemical cell containing three-electrode integrated in a small disposable micropipette tip. The electrodes were manufactured using 3D pen and a commercial carbon black-polylactic acid filament and the tip-based cell was fabricated using alternative materials. The cell requires low sample volumes (10 μL) and may be operated with several commercial micropipettes (manual and electronic) that performs the aspiration of solution before or simultaneously to the electrochemical measurement, resulting in electroanalysis under static or flowing conditions, respectively. As proof-of-concept, measurements of catechol were performed in stationary and hydrodynamic mode, in which the sensitivity of the hydrodynamic was around five-fold greater when compared to the stationary method (47 vs 9 nA μmol−1 L), due to the faster mass transport of the analyte. Moreover, the proposed cell exhibited analytical parameters for catechol comparable with a commercial screen-printed electrode. The versatility of the cell was also demonstrated for square wave anodic stripping voltammetry in the presence of lead ions, in which the deposition (pre-concentration) step was performed during the solution aspiration controlled by an electronic pipette. The obtained LOD was 6-fold better than a conventional system for ASV (0.010 vs 0.059 μmol L-1). The analytical feasibility of the cell was demonstrated through the determination of catechol and lead in tap and ground water, being obtained recoveries close to 100%. The proposed cell and is cheaper (< US$ 0.10), smaller and more versatile than other tip-based and 3D-printed cells, being promising for on-site analyses and education purposes.