Applications Of Gold Nanoparticles Enhanced Reactive Oxygen Species Chemiluminescence In Environmental Analysis

Chemiluminescence (CL) analysis is characteristic of high sensitivity, wide linear dynamic range, and the need of relatively simple and inexpensive instrumentation. It has been widely used in chemistry, biology and environment. Recently, gold nanoparticles are found to catalyze some CL systems, such as the luminol-H2O2 system, bis(2,4,6-trichlorophenyl) oxalate-H2O2 system, and KIO4-NaOH-Na2CO3 system. However, in all the pubulished gold nanoparticles-triggered CL systems the influence of high ionic strength and pH value on the catalytic activity of the gold nanoparticles hasn't been reported. In this work, gold nanoparticles in high salt solution and wide pH range are used to enhance the CL intensity of reactive oxygen species, which were applied in enrionmental analysis. It consists of three sections:(1) Nonionic fluorosurfactant molecules (FSN)-capped gold nanoparticles exhibited excellent stability in the presence of high salt concentrations and a wide pH range. In this study, FSN-capped gold nanoparticles are used for investigating Na2CO3-ONOOH system. The CL intensity is proportional to the concentration of nitrite in the range from 0.1 to 100 mmol/L. The detection limit (S/N=3) is 0.036μmol/L and the relative standard deviation (RSD) for seven repeated measurements of 0.5μmol/L nitrite was 2.4%. This method has been successfully applied to determine nitrite in tap waters with recoveries of 97%～106%.(2) We utilized FSN-capped gold nanoparticles of different sizes to distinguish the emitting species from H2O2-Co2+-NaOH and H2O2-Co2+-NaHCO3 systems. The variation of CL spectra and UV-vis spectra, as well as the quenching effect of reactive oxygen species scavengers were studied in detail to understand the CL enhancement mechanisms of FSN-capped gold nanoparticles on the two systems.(3) We studied the effect of unreacted gold(III) chloride (AuCl4-) during the preparation of gold nanoparticles on CL intensity. AuCl4- was found to enhance remarkably the CL emission generated from HCO4-decomposition, and bisphenol A can inhibit greatly the CL intensity of AuCl4--HCO4- system. Based on these phenomena, a new flow-injection CL method, without any special CL reagent, e.g. peroxyoxalate and luminol was developed for the determination of bisphenol A in aqueous solution. The proposed method was developed for the direct determination of bisphenol A in polycarbonate plastics with satisfactory results. In addition, based on the CL spectrum, UV-visible spectra and the quenching effect of reactive oxygen species, a reasonable CL mechanism from the AuCl4--HCO4--bisphenol A system was proposed.