عنوان مقاله [English]
Here in a dispersive liquid- liquid microextraction based on solidification of floating organic drop method was developed for simultaneous pre-concentration and trace determination of cadmium, lead and cobalt ions based on their complexes with dithizone and preprocessing spectrophotometric data by net analyte signal based method. The affecting parameters on extraction were investigated and optimized simultaneously. The optimum conditions for pH, extraction solvent, extraction solvent volume, dispersive solvent, dispersive solvent volume, contact time, centrifugation time, solidification time and freezing temperature were 8, 1-ndecanol, 150 microliter, ethanol, 350 microliter, 10 min, 6 min, 5min and 4 oC, respectively. Under these conditions and using a sample containing 15 ml of the cations, the detection limits were 1.1 µg L-1, 3 µg L-1 and 5.4 µg L-1 for cadmium, lead and cobalt, respectively. Because of spectra sever overlapping of complexes throughout studied pH and spectra regions, the net analyte signal ratio spectra method was used to resolve the problem perfectly. Hence, the determination of studied cations can be conducted in the presence of other complexes and unknown interferences. Ultimately, the modified method was successfully applied for determination of aforementioned cations in real samples.