Development of simple, sensitive and selective detection probe for Hg(II) ions in natural water is still a challenge to the researchers due to stringent and permissible limits set by World Health Organization (WHO). Herein, highly selective optical (absorbance and fluorescence modes) sensing probe for monitoring Hg(II) ions in synthetic urine and ground water has been successfully demonstrated using gold nanoparticles (AuNPs)/rhodamine B (RB)/hexanedithiol (HDT) nanocomposites system. The incorporation of RB and HDT on AuNPs improved sensitivity and selectivity (1.8 times) towards Hg(II) ions over other metal ions, respectively. The proposed mechanism involved in Hg(II) sensing in absorbance mode was based on aggregation of composites AuNPs, while fluorescence mode was based on the turn on fluorescence approach through release of RB from AuNPs/RB/HDT nanocomposites system via subsequent formation of Hg-HDT complex. The linear dynamic range for detection of Hg(II) ions using AuNPs/RB/HDT nanocomposite system, when tested in optimized colorimetric and fluorescence based analytical method adopted to the Hg(II) spiked urine and ground water samples exhibited detection limit of 1 ng mL⁻¹ (1 ppb) and 0.5 ng mL⁻¹ (0.5 ppb) using absorption and fluorescence mode, respectively, which were significantly comparable to those used in other developed Hg detection probes.

由于世界卫生组织（WHO）设定的严格和允许的限制，开发天然水中Hg（II）离子的简单，灵敏和选择性的检测探针仍然是研究人员面临的挑战。在此，使用金纳米颗粒（AuNPs）/若丹明B（RB）/己二硫醇（HDT）纳米复合材料系统成功地证明了用于监测合成尿和地下水中Hg（II）离子的高选择性光学（吸收和荧光模式）传感探针。在AuNPs上掺入RB和HDT分别提高了对Hg（II）离子的敏感性和选择性（是其他金属离子的1.8倍）。所提出的涉及吸收模式下Hg（II）感测的机理是基于复合AuNPs的聚集，而荧光模式则基于开启荧光方法，即通过随后形成Hg-HDT复合物从AuNPs / RB / HDT纳米复合材料系统释放RB来开启荧光方法。使用AuNPs / RB / HDT纳米复合材料系统检测Hg（II）离子的线性动态范围，当采用优化的比色法和基于荧光的分析方法对加标的Hg（II）尿液和地下水样品进行检测时，检出限为1 ng毫升^-1（1 ppb）和0.5 ng mL ^-1（0.5 ppb）分别采用吸收和荧光模式，与其他已开发的Hg检测探针可比。