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 mug 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 mug 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 mug ml(-1) Hg (II)]. The precision was determined from 25 results obtained for 2.5 x 10(-5) M Hg(II); the mean value of Hg(II) was 2.53 x 10(-5) M with a standard deviation of 1 x 10(-7) M Hg(H). The proposed method has been applied to the determination of mercury in water samples.