Solvent Extraction-Spectrophotometric Determination of Nickel(II) in Natural Waters Using DI-2-Pyridyl Ketone Benzoylhydrazone

A new analytical method using the reagent di-2-pyridyl ketone benzoylhydrazone (DPKBH) as a colorimetric chelating agent for the spectrophotometric determination of Ni(II) in natural water samples wasestablished. This method involves a liquid-liquid extraction and was developed for determination of trace amounts of Ni(II). Under the established optimal conditions Ni(II) can be quantitatively extracted with DPKBH in chloroform. The yellow Ni(II)-complex exhibits one maximum absorbance at 406 nm. The chelated nickel(II) obeys the Beer's law and the method is suitable in the concentration range from 0.3 to 9.4 μg/L. In order to validate the method, Ni(II) concentration was determined in a water sample and the result was compared with the value obtained by AAS method. The results are in good agreement. When the spectrophotometric method was used, fluoride ions were added in order to mask the presence of iron, which can be present in water samples and is the principal interferent. The advantages of the proposed method are the short time required, high sensitivity, good precision and the use of non-expensive instrumentation.