Spectrophotometric Determination of Phenolic Compounds Based On Silver Nanoparticles Surface Plasmon Peak

Metal nanoparticles have received considerable interests in recent years for their unusual optical and electrical properties. Metals such as Ag and Au can produce free electrons that exhibit quantized waves called plasmons. They can interact with visible light in a phenomenon called surface plasmon resonance (SPR) [1]. When dispersed in liquid media, these nanoparticles exhibit a strong UV–vis extinction band that is not present in the spectrum of the bulk metal. SPR excitation results inwavelength-selective absorption with extremely large molar extinction coefficients (~ 1011 M-1 cm-1) [2]. Phenolic compounds such as dihydroxybenzenes (DHBs) are released into the environment because they are used in photographic developers, tire adhesives, rubber antioxidants and antiozonants, monomer inhibitors, wood adhesives, ultraviolet absorbers and optical brighteners, dyestuffs, pharmaceuticalformulations, and miscellaneous derivatives. Dihydroxybenzenes are important environmental pollutants because they are toxic to humans and difficult to degrade. So, it is very important to develope simple and rapid analytical methods for sensing and monitoring the concentration level of these harmful compounds owing to their toxicity and persistence in the environment [3].In this work, hydroquinone (1,4-dihydroxybenzene) and pyrogallol (1,2,3-trihydroxybenzene) aredetermined based on their ability to reduce Ag+ for generation of Ag_NPs in the presence of sodium citrate as stabilizer (Scheme 1). Their absorbance at λ = 430 nm are used for quantitative analysis.