Fluorescence detection of cyromazine using gallic acid-reduced gold nanoparticles

This paper describes a novel fluorescence gold nanoparticles probe for detecting cyromazine. Gold nanoparticles (GNPs) were synthesized in one step at ambient temperature using gallic acid (GA) as reducer and stabilizer. Typically the prepared GNPs with the average diameter of ∼37 nm can emit stable fluorescence at 318 nm when the excitation wavelength was selected as 296 nm. Upon the addition of cyromazine, the reducer GA can interact with cyromazine through strong hydrogen-bonding interaction, which can interrupt the formation of gold nanoparticles. Consequently, the color change from purple to yellow-green with increasing cyromazine concentration was observed, coupling with the solution fluorescence intensity weaken at the same time. Because of the unconspicuous color change, we focus on detecting the change of the fluorescence intensity. Under the optimum conditions, the weakening of the fluorescence intensity exhibited a linear dependence on cyromazine concentration in range of 0.07–5.90 μM. The selectivity of cyromazine over other metal ions and pesticides in aqueous solution is remarkably high with a low detection limit of 0.07 μM. In the analysis of practical spiked milk and pet food samples, the new method yielded satisfactory results. This approach offers several advantages including simplicity (without temperature control and GNPs modification), speediness, high selectivity and sensitively, and a large linear range.