Onsite-detection of barium and nickel from river, pond and tap water samples using gold nanoparticles as a chemical sensor.

We report a simple, selective and sensitive colorimetric assay for onsite determination of Ni(II) and Ba(II) from river, pond and tap water samples using the localized surface plasmon resonance (LSPR) of malonate capped gold nanoparticles (AuNPs) as a chemical sensor. The method is based on the color change and red shift of LSPR absorption band in visible region that caused by the aggregation of NPs because of the coordination complex between Ba(II) and Ni(II) with carboxylate ions of malonate capped AuNPs. The determination of Ba(II) and NI(II) in a same sample was performed by masking one of the analyte at a time, EDTA was used to mask Ni(II) for detection of Ba(II) and dilute H2SO4 was used to mask the Ba(II) for detection of Ni(II). The linear range for quantitative determination of Ba(II) and NI(II) were found in the range of 15-500 and 10-500ngmL-1 with a limit of detection of 5 and 3ngmL-1, respectively. The advantages of the AuNPs based chemical sensor is found to be simple, rapid and sensitive as well as it can be applied at the sample source for trace detection of Ba(II) and Ni(II) in various environmental samples.