Abstract

A rapid and sensitive approach for colorimetric sensing of formaldehyde in aqueous solutions and leather has been developed based on the morphology-dependent localised surface plasmon resonance (SPR) properties of gold nanorods (AuNRs). The method relied on amalgamation between elemental mercury (Hg0) and AuNRs to generate significant colour change, which was dependent on the amount of Hg0. Upon formaldehyde introduction into the mixed solution of Hg2+ and gold nanorods, formaldehyde would reduce Hg2+ to Hg0 in an alkaline environment, which results in the longitudinal plasmon wavelength of gold nanorods to blue shift accompanying a perceptible colour change from blue-green to purple. Under optimal conditions, the linear correlation could be fitted between Δλ and the concentration of formaldehyde ranging from 0.1 to 10mg/L with a linear correlation coefficient of 0.992. Relevant experimental parameters, including pH, concentrations of Hg2+, reaction time were evaluated. Meanwhile, the sensing mechanism for the detection of formaldehyde has been discussed. Due to its great applicability, simplicity and rapidity, the proposed colorimetric approach is promising to be applied to formaldehyde determination in leather.