Development of a dispersive liquid-liquid microextraction (DLLME) method for the determination of metal in water samples using organic reagents and UV-VIS spectrophotometry

In the present study, new, sensitive, simple, efficient and validated method was developed for the determination of Ni(II), Cu(II) and Zn(II) in different water samples using dispersive liquid-liquid microextraction (DLLME) technique followed by spectrophotometric analysis. The procedure is based on the complexation of Ni(II), Cu(II) and Zn(II) with a new complex of 4-benzoyl-N-[(diethylamino)carbonothioyl]-1,5-diphenyl-1H-pyrazole-3-carboxamide, then the extraction of the complex using DLLME technique. Some important parameters such as the type and volume of extraction and dispersive solvents as well as the extraction period were investigated and optimized in detail. Under the optimum conditions, the calibration graphs for Ni(II), Cu(II) and Zn(II) were linear over the ranges of 0.033-0.666, 0.132-4.000, 0.033-5.000 µg mL-1 with the limits of detection of 0.012, 0.027, 0.159 µg mL-1 respectively. Relative standard deviations for five replicate measurements of Ni(II), Cu(II) and Zn(II) at 0.066, 0.132, 3.330 μg mL-1 was calculated as 7.1 %, 9.4 %, 1.9 % respectively. The method was applied to water samples. Keywords: Preconcentration, microextraction, UV-VIS Spectrophotometry, water samples, metals.