Silver Nanoparticles and Polydimethylsiloxane-coated Paper for the Simultaneous Detection of Ascorbic Acid and Hydroquinone

This study developed a novel paper-based sensor for the simultaneous analysis of ascorbic acid (AA) and hydroquinone (HQ). The sensor utilized polyvinyl alcohol (PVA)-stabilized silver nanoparticles (AgNPs-PVA) as the reagent probe and PVA media acted as the filter for separation of the analytes. Polydimethylsiloxane (PDMS) and ethanol serve as the stationary phase and eluent, respectively, exploiting the differences in analyte reactions and solubility to achieve their separation on the filter paper. The circular sensor's central zone was AA's detection area, while HQ was detected in the outer ring region. AA induced an immediate color change in the test kit, whereas HQ required a 20-minute elution with ethanol followed by colorimetric analysis. All analytes exhibited relative standard deviations of repeatability and reproducibility below 2.7% and 9.5%, respectively. Under optimal conditions, the linear detection range for HQ was 0.2-2.0 mg & sdot;L- 1, while AA was 0.1-2.0 mg & sdot;L- 1. The detection limit was determined to be 0.05 mg & sdot;L- 1 for AA and 0.1 mg & sdot;L- 1 for HQ. The recoveries of AA and HQ in cosmetic cream samples ranged from 80 to 110%. The accuracy of the sensor's measurements was further validated by comparison with the HPLC-DAD method.