Determination Of Trace Amounts Of Heavy Metal Ions In The Environment By Light Scattering Technique

In this paper, resonance light scattering (RLS) analysis technique and its application were described. It was focused on the applications of the. detection of heavy metal ions. On the basis of previous work, new methods to determine the Cu (Ⅱ) and Cr (Ⅵ) in environmental samples were established based on the enhanced RLS intensity of ion-associate complex which formed with two opposite kinds of ions by electrostatic and hydrophobic interactions and further expanded the research field of RLS technique determination of heavy metal ions. In addition, gold nanoparticles got aggregated owing to small organic molecules interacted with Hg (Ⅱ) on its surface, and localized surface plasmon resonance (LSPR) scattering intensity remarkably enhanced. As such, a new method of Hg (Ⅱ) determination was established. Main research contents as follows:(1) A RLS detection method for Cu (Ⅱ) has been developed based on the enhanced RLS signals at 370 nm from 1,10-phenanthroline by Cu (Ⅱ) with the presence of eosin Y in acidic aqueous medium. The enhanced RLS signal intensity is proportional to the concentration of Cu (II) in the range of 10.4～·127 ng/mL. The linear equation is△IRLS=9.2+8.3 c (c, ng/mL). The limit of detection (LOD) (3σ) is 1.0 ng/mL. The acidity of system, ionic strength and other factors have been investigated. The method has been applied to the determination of trace amounts of Cu (II) in tap water and river water. The RSD is less than 3.0%.(2) In the strong acidic conditions, Cr (VI) with strong oxidizability could oxidize I- into I2 and result in I3-formation in presence of excessive I-. A RLS detection method for Cr (VI) has been developed based on the enhanced RLS signals at 378 nm from ion-associate complex by I3-with the presence of berberine hydrochloride (BH). In the optimum experimental conditions, the enhanced RLS intensity is proportional to the concentration of Cr (VI) in the range of 0.2～3.6μmol/L with the detection limit (3σ) of 12 nmol/L. The linear equation is△IRLS=13.4+995.3 c (c,μmol/L). This method has been applied to the determination of Cr (VI) in the water samples with satisfactory results.(3) Under the conditions of pH 9.0 B-R buffer, trace Hg (II) induced mercaptoacetic acid-coated gold nanoparticles to assemble, and LSPR scattering intensity at 548 nm remarkably enhanced. PEG20000 was used to protect the aggregation of gold nanoparticles. The enhanced LSPR scattering intensity is proportional to the concentration of Hg (II) in the range of 0.08～0.8μmol/L. The linear equation is△ILSPR=0.04+409.3 c (c,μmol/L). The LOD (3σ) is 10.3 nmol/L. The LSPR analysis technique of determination of trace Hg (II) has been developed. The method was simple, fast and sensitive.