Batch injection electroanalysis with stainless-steel pins as electrodes in single and multiplexed configurations

In this work, mass-fabricated stainless-steel pins are used as low-cost electrodes in a batch injection analysis (BIA) system with electrochemical detection (BIA-ED). The system consists of a polypropylene container including a potentiostatic three-electrode configuration cell designed using a pin coated with carbon ink as working electrode and two bare pins as counter and reference electrodes. These pins are directly punched into the bottom of the container and connected to the potentiostat using a commercial female connection. The system shows good precision for measurements performed employing the same or different electrochemical cells (RSD 7.2 and 8.9% respectively). The platform is applied to the determination of epinephrine in a pharmaceutical real sample showing accurate results. As a proof-of-concept, the feasibility of constructing a multiplexed BIA-ED system based on pins is evaluated by incorporating eight pin-based working electrodes in the container. The electroanalytical platform is completed with one reference and one auxiliary pin electrodes that are shared for all the eight working electrodes. It demonstrates the versatility that pins can provide to the construction of different electroanalytical systems. Moreover, the system is designed in such a way that an eight-channel micropipette can be employed for injections, making the system simpler and faster.