Author: E.Fitriany, M. Harsini, F. Kurniawan, B. A. Widyaningrum and D. R. A

DOI: http://doi.org/10.31788/RJC.2026.1929663

A novel electrode modification strategy was developed. It involved electropolymerization of melamine andelectrodeposition of gold nanoparticles (AuNPs) onto a carbon paste electrode (CPE), forming a polymelamine(PM)/AuNPs-modified electrode. The fabricated AuNPs/PM/CPE electrode was designed for the simultaneousdetermination of uric acid (UA) and dopamine (DA). Field Emission Scanning Electron Microscopy-EnergyDispersive X-ray analysis (FESEM-EDX) revealed that the AuNPs/PM/CPE electrode exhibited a surfacemorphology with a large effective area, facilitating enhanced electrochemical activity for the simultaneous detectionof both compounds in human urine samples. Optimisation studies determined that a scan rate of 100 mV/s wasoptimal. A 0.1 M phosphate-buffered saline (PBS, pH 3.0) solution was selected as the supporting electrolyte for simultaneous determination. The LoD values for DA and UA were 0.6052 μM and 0.6462 μM, respectively, withhigh correlation coefficients (R² = 0.9981 for DA and 0.9979 for UA). The sensor showed strong analytical performance, with recoveries of 89.6–109.2% for DA and 83.4–105.1% for UA. Precision values ranged from0.02–0.70% for DA and 0.06–0.63% for UA. The standard-addition (spiking) method applied to human urine yieldedrecoveries of 98.99% for DA and 98.96% for UA at a concentration of 1 μM. The developed sensor provides a rapid, cost-effective, and minimally invasive approach for monitoring DA and UA in urine, offering considerable potential for early diagnosis and clinical screening of neurological and metabolic disorders. Its superior analytical performance is attributed to the uniform dispersion of AuNPs, which enhances electron transfer efficiencyandcatalytic responsiveness.

Keywords: Gold nanoparticles, Polymelamine, Uric acid, Dopamine, Electrochemical sensor.