Fluorometric determination of Au3+ via hydrolysis of thiocarbonate with bromide as a masking agent

Gold ions are very important in chemistry and materials science owing to their various uses in chemical reactions as well as industrial and biological applications. In this study, we developed a novel reaction-based probe (GP), which is a thiocarbonate derivative of the 2-(2-hydroxyphenyl)benzothiazole dye, for the selective and sensitive determination of Au3+. The probe GP showed turn-on fluorescence signaling behavior toward Au3+ ions triggered by the metal-induced hydrolysis of the thiocarbonate group. Interference from other thiophilic ions, Ag+ and Hg2+, was effectively eliminated by using bromide ions as a masking agent. Prominent off-on type fluorescent sensing of Au3+ over other coexisting metal ions was possible with a detection limit of 4.8 x 10(-8) M (9.5 ppb). Fluorescence sensing of Au3+ by GP was fast and applicable over a wide pH range between 4.0 and 10.5. Application of the probe to the analysis of Au3+ in synthetic wastewater was conducted using an easily accessible smartphone.