Highly Selective Separation and Determination of Mercury (II) Using N,N′‐bis(2‐mercaptophenyl)ethanediamide

Abstract

The present work describes a selective and economical method for the determination of mercury using N,N′‐bis(2‐mercaptophenyl)ethanediamide (H₂L). The investigation included a study of the characteristics that are essential for solvent extraction and separation of mercury (II). Furthermore, a highly sensitive, selective, and rapid spectrophotometric method is described for the determination of trace amounts of mercury (II) by H₂L. This compound reacts with mercury (II) in the range of pH 2–10 to produce a red complex [1:1 mol ratio of Hg(II)/H₂L] soluble in dichloromethane. The complex was found to obey Beer's law from 5–128 µg ml⁻¹ with an optimum range when the preconcentration factor is one. The concentration limits in Beer's law are reduced from 0.2–5.12 µg ml⁻¹ with an optimum range when the preconcentration factor is 25. The relative standard deviations were calculated as 0.05% [15 samples, each containing 5 µg ml⁻¹ Hg (II)]. The precision was determined from 25 results obtained for 2.5 × 10⁻⁵ M Hg(II); the mean value of Hg(II) was 2.53 × 10⁻⁵ M with a standard deviation of 1 × 10⁻⁷ M Hg(II). The proposed method has been applied to the determination of mercury in water samples.

Keywords:

• Hg (II) determination
• Separation
• Preconcentration
• Spectrophotometry
• Solvent extraction
• N,N′‐bis(2‐mercaptophenyl)ethanediamide

Acknowledgments

This work was financially supported by the Scientific and Technical Research Council of Turkey [Project TBAG 2307(103T041)] and the Balıkesir University Research Center of Applied Science (BUCAS).