Sustainable validated methodology for enzymeless determination of Tyrosine using 3D-printed PLA/CB electrodes in synthetic urine

• Tyrosine could help Alzheimer's and colon cancers diagnostic and prognostic. • 3D-printed electrochemical devices could improve biomarkers clinical investigations. • The method selectivity at synthetic urine by matrix effect studies was satisfactory. • Statistical tests assure the suitability of linearity, LOD, LOQ, and accuracy. Tyrosine (TYR), an amino acid, is a biomarker for several diseases, making its quantification in biological samples clinically relevant. However, conventional gold-standard methods typically require expensive reagents, are time-consuming, and are often not portable. In addition, in most cases, TYR assays are not validated. To circumvent these inconveniences, we present a validated and sustainable methodology for quantifying TYR in synthetic urine (proof-of-concept) on a portable 3D-printed platform. This work evaluated and achieved promising results in the use of 3D printing in the development of a miniaturized and portable analytical method, which explored aspects of analytical validation. The proposed method was optimized for square wave voltammetry parameters and better background electrolytes, resulting in the following optimized conditions: 8 Hz frequency, 50 mV modulation amplitude, 6 mV pulse increment, and sodium acetate buffer (pH 4.5). Validation, performed according to EURACHEM, IUPAC and ICH guidelines, evaluated key performance indicators such as selectivity (via matrix effects and Youden's calibration study), linearity, limits of detection and quantification, precision, and trueness. The method demonstrated adequate selectivity and linearity over the working range of 2 to 10 µmol/L ( p > 0.05). At 6 µmol L −¹ , it showed good repeatability ( n = 6) and intermediate precision ( n = 12), with an RSD (%) of less than 16%. Recovery tests evaluated accuracy using spiked samples at 2, 6, and 10 µmol L − ¹ ( n = 3), with recoveries below 106%. In addition, the proposed method achieved a high greenness score of 0.79, calculated using the AGREE software, where higher scores indicate more environmentally friendly methods. Overall, the proposed method is a low-cost, sustainable, environmentally friendly, portable, and accessible approach for TYR analysis in biological samples.