A novel smartphone-based electrochemical hydroquinone sensor using renewable electrocatalyst of carboxyl-functionalized carbon nanofiber derived from white seabass scale collagen

A smartphone-assisted square wave voltametric hydroquinone (HQ) sensor was developed based on novel functionalized carbon nanofiber (f-CNF) derived from a sustainable precursor of white seabass (Lates calcarifer) scale collagen via slow pyrolysis carbonization. The as-prepared f-CNF exhibited a consistent fibrous structure with a large surface area, high graphitic content, high crystallinity, abundant carboxyl groups, and excellent dispersibility. The f-CNF was drop-cast on a screen-printed carbon electrode (f-CNF/SPCE). The proposed sensor exhibited high electrical conductivity, rapid electron transfer, a large electroactive surface area, a high number of adsorption sites, and outstanding electrocatalytic activity. The portable HQ sensor demonstrated a wide linear detection range from 1.0 to 150 μM (R² = 0.9959) with a limit of detection (LOD) at 0.54 μM. Reproducibility and selectivity were excellent. The highlights of this electrochemical sensor are reusability for up to 18 cycles (90 individual measurements) and high stability for 8 weeks in use and 12 weeks in storage. The f-CNF/SPCE successfully detected HQ in pharmaceutical samples, achieving acceptable recoveries from 96.1 to 102.9 %. The results were consistent with those obtained using UV–Vis spectrophotometry and with product label information. Additionally, the square wave voltametric sensing application allows for the simultaneous detection of HQ, catechol (CC), and resorcinol (RS).