Development of a simple analytical method to determine arsenite using a DNA aptamer and gold nanoparticles

A simple analytical method was developed to determine the arsenite (As(III)) concentration using a DNA aptamer and gold nanoparticles (AuNPs). Prior to sample measurements, the method sensing mechanism was confirmed by analyzing the particle size of the AuNPs at each step of the analysis procedure, and the key operational parameters that affect the method performance were optimized. The optimal final NaCl concentration, incubation time with NaCl and pH of a 3-(N-morpholino) propanesulfonic acid buffer were 60 mM, 10 min and 7.3, respectively. A calibration curve was created under optimized operational conditions. The calibration curve was linear from a 1.0- to 10-μM As(III) concentration. The detection limit was 2.1 μM (161 μg/L). Using the calibration curve, we evaluated groundwater samples spiked with As(III). As(III) concentrations in groundwater pretreated with a 0.2-μm-pore-size membrane filter and cation-exchange resin were determined by using the method, which suggests that the proposed method can be used to determine the As(III) concentration in groundwater.