Spectrophotometric determination of Cd(II) and Hg(II) with 2-(2`-hydroxynaphthyl azo-)benzothiazole; Application to Environmental Samples

T. Y. Mohamed, A. S. Amin, A. A. Mousa


A sensitive, selective and rapid method has been developed  for the determination of   micrograms per liter level of Cd (II) and Hg (II) based on the reaction  with  2-(2`-hydroxynaphthylazo-)benzothiazole(HNABT). The HNABT reacts with Cd(II) and Hg(II) in the presence of universal buffer solution ( pH  9.0-10.5) . The molar absorptivity and Sandell sensitivity for Cd(II) complex are  5.0 ×104 L mol-1 cm-1 ,0.00224 μg cm-2 at 630 nm, whereas those values for Hg (II) complex are 2.1×104 L mol-1 cm-1 , 0.00955 μg cm-2 at 623 nm.   Beer’s law is obeyed in the range of 0.11-4.18 and 0.1-6.02 μg ml -1 for Cd (II) and Hg (II) complex, whereas Ringbom optimum concentration ranges found to be 0.2-4.0 and 0.20- 5.85 μg ml -1 ,respectively.  Standard deviation and relative standard deviation are 0.004604, 1.45% for Cd(II) complex and 0.00396, 1.26% for Hg (II) complex . The detection and quantification limits (3δ, three standard deviation) are 0.31 and 0.91 ng ml-1 for Cd(II)-complex, whereas 1.14 and 3.8 ng ml-1 for  Hg(II)- complex. The proposed method was applied successfully to the determination of Cd (II) and Hg (II) in Soil and water samples, and the results were compared with that obtained using AAS method.


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