3D-printed electrochemical sensor applied to the determination of nitrite: A cost-effective and portable platform for environmental and clinical monitoring

• An innovative electroanalytical method utilizing a fully 3D-printed device for the determination of nitrite in complex samples has been proposed. • This method offers portability, low cost, and needs small amounts of samples and chemicals. • The proposed approach presents a promising alternative to traditional methods. • Complex samples were analyzed without any pre-treatment, needing only a straightforward dilution in the background electrolyte. Nitrite (NO 2 ˉ ) is an essential compound present in various processes in nature, which ranges from environmental to biological systems. It is widely used in both food and chemical industry, and even in the production of medicines. However, the excess of NO 2 ˉ can cause severe damage to both the environment and human health. With this concern, this work presents a novel and easy to produce platform, entirely projected and constructed by additive manufacturing, rising a miniaturized and portable electrochemical system for the determination of NO 2 ˉ in water and synthetic saliva samples. The set of three electrodes was easily obtained by fused deposition modeling, using a carbon black-based filament feeding the 3D printer. The surface of the electrochemical sensors was treated to expose conductive particles and enhance their electrochemical performance. The differential-pulse voltammetry technique was meticulously chosen and fully optimized using multivariate methods to achieve the best operational conditions for the NO 2 ˉ determination. The proposed method presented a linear dynamic range from 5.0 to 500.0 µmol L ⁻¹ , with a limit of detection of 1.8 µmol L ⁻¹ . Besides, interference tests demonstrated a good selectivity of the method. Recovery values close to 100 % for water and simulated saliva samples demonstrate the applicability of the developed method. In this context, the 3D-printed electrochemical device becomes a potential alternative for the on-site, reliable, and fast determination of NO 2 ˉ .