Rapid Determination of Trace Hg²⁺ in Water with Enrichment-Part Elution-Solid Phase Spectroscopy

By using a hyphenated solid phase extraction (SPE) and solid phase spectroscopy designed by our group, a rapid, sensitive and selective method for detecting Hg²⁺ in river water is developed. Hg-dithizone produced with dithizone and Hg²⁺ can be enriched on a mixed cellulose membrane, and the residual dithizone was removed by washing the membrane with sodium hydroxide solution. Then, visible diffuse reflectance spectroscopy was used for the quantitative analysis of Hg²⁺ in situ. As such, unwanted interference from other contaminants was minimized by washing the membrane to remove dithizone; EDTA disodium is also added to mask Cu²⁺ and Cd²⁺. Under the optimal conditions, the liner range of the method is 0.5−30 μg/L with a squared correlation coefficient of 0.993, and the limit of detection is 0.444 μg/L. The method is applied to the quantification of Hg²⁺ in tap-water and river water. The recovery rates achieve 91.3%−108.0%, and the relative standard deviations of parallel tests range from 2.06 to 9.68. This work offers a fast method for the determination of Hg²⁺ in river water with high sensitivity and selectivity.