Study On The Designs Of Mercury (Ⅱ)Optical Sensors And Their Analytical Applications In Environmental Water Sample

As the increasing research of environment, more and more people pay attention to heavy metals. Mercury is one of the most dangerous heavy metal pollutants, which mainly exists in water. Mercury with the highly mobility and bioaccumulation can cause an infinite harm to human health. Therefore, it is obviously of great necessity to analyze mercury in water environmental. This paper reports a series of light sensors for mercury ion detection based on the backward light scattering technology, UV-vis light-splitting technology and fluorescent light-splitting technology and discusses their reaction mechanisms and analytical applications to the determination of mercury ions in the real water sample. The details are follows:(1) In faintly acidic medium, a backward light scattering (BLS) analytical method of mercury (II) have been established based on the enhanced BLS signal due to the interaction of mercury (II) and quercetin (QT). The QT act as a scattering probe who can bring the backward light scattering signal (IBLs) increased obviously at471nm while interaction with mercury (Ⅱ) in pH6.8Britton-Robinson (BR) buffer medium. The enhanced BLS intensity is proportional to the content of mercury (II) in a range of0.2-3.0μmol/L. The limit of detection is20nmol/L. This method has been successfully applied to the determination of mercury (Ⅱ) in laboratory waste water and tap water samples with the recovery range of95.5%～102.3%and RSD≤3.0%.(2) In this work, the colorimetric detection assay of mercury has been proposed based on silver nanoparticles (AgNPs) aggregation. The stable and monodisperse silver nanoparticles. which coated by polydopamine, was prepared by a one-pot reduction process using dopamine as a reducing agent. The polydopamine adsorption with Hg2+can induce the aggregation of silver nanoparticles resulting in the decrease of absorption signal of AgNPs at405nm and the color change of the solutions. It was found that the decreased absorption signal intensities was proportional to the mercury content in a range of0.5～5.0μmol/L. According to this, the ultraviolet-visible absorption spectrum method and colorimetric method for determination of Hg2+was developed. The limit of detection is50nmol/L. In this work, UV-vis absorption spectrum, scanning electron microscope (SEM) and infra-red (IR) spectrum were investigated. The mechanism of this reaction was discussed. The proposed method was successfully used to detection of Hg2+in tap water with a recovery range of93.0%to105.5%with RSD≤4.4%.(3) The fluorescence of acridine orange (AO) can be quenched while interaction with T bases-riched single stranded DNA (ssDNA) in aqueous solution. When mercury (II) is added, the specific effect between T bases and mercury (II) make ssDNA form T-Hg2+-T mismatched double stranded DNA (dsDNA). And then AO molecules can insert in the interspace of dsDNA and bring about the recovery of the fluorescence. According to this, the highly selective fluoresent sensor for mercury (II) is established. The linear range is0.1-0.8μmol/L. The limit of detection is10nmol/L. The mechanism was discussed in this work. The proposed method has been successfully applied to the determination of mercury (II) in laboratory waste water samples with a recovery range of97.0%to110.0%and RSD≤4.0%.