Abstract:
A graphene quantum dot-nano activated carbon /chitosan/PVA composite film for hydroquinone
detection was developed. The film, composed of chitosan (0.0-4.0 wt%), polyvinyl alcohol (8.0-12.0 wt%),
cross-linking agent (0.1-1.0 wt%), graphene quantum dots (1.0-4.0 wt%), and nano-activated Carbon (0.1-2.0
wt%) with deionized water as the solvent, exhibits both absorbent and light-shine properties. The film's
adsorption efficiency towards hydroquinone was evaluated under controlled conditions (room temperature,
pH 7, and 6 hours). Detection relies on the colorimetric change of the film from yellow-green to blue upon
hydroquinone binding. The linear range of hydroquinone measurement was determined to be 1.0-150 mg/L
based on the B-value from RGB vs. hydroquinone concentration plot. The limit of detection (LOD) was found
to be 0.5 mg/L. The stability of the film, stored in a ziplock bag, was assessed for 20 days, demonstrating
consistent color retention. The method's accuracy was evaluated by analyzing standard curves (n=3) within
one day. The standard deviation (SD) of the parameters in the linear equation was less than 0.014, confirming
acceptable precision. The percentage recovery of hydroquinone at concentrations of 2.5 and 40 mg/L was
106% and 95%, respectively, further validating the method's accuracy. The specificity of the method was
investigated by introducing potential interfering substances such as ascorbyl glucoside, arbutin, Kojic acid, and
catechol at the same concentration as hydroquinone (1 mg/L). Only catechol significantly interfered with the
hydroquinone measurement, demonstrating good specificity for hydroquinone detection. This study presents
a novel film-based method for hydroquinone detection with high sensitivity, accuracy, and specificity. The film's
simple preparation, stability, and visual readout offer a promising tool for on-site hydroquinone monitoring.