Graphite Furnace Atomic Absorption Spectrometry Determination of Trace amounts of Nickel in Water Samples after Homogeneous Liquid-Liquid Microextraction via Flotation Assistance

The determination of low levels of nickel has become increasingly very important in environmental chemistry since its negative role in the human life. It is generally impossible to determine trace nickel in environmental samples directly because of interfering species in the surrounding matrix, or the concentration of the analyte being below the detection limit of the instrument. So preconcentration and separation techniques are still necessary. In this work, an efficient microextraction method was applied to the separation and preconcentration of Ni(II) namely homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA). Ni(II) was complexed with 1-(2-pyridylazo)-2-naphthol (PAN) and was extracted to microvolume toluene phase. In this research, a special extraction cell was designed to facilitate collection of the low-density solvent extraction. The enriched analyte in the floated organic phase was determined by graphite furnace atomic absorption spectrometry (GFAAS). The parameters affecting the extraction efficiency of the proposed method such as the type and volume of extraction and homogeneous solvents, pH, extraction time, the chelating agent amount, and ionic strength were studied and optimized. Under optimum conditions, the calibration graph was linear in the range of 1.0–500 μg/L with a detection limit of 0.5 μg/L. The correlation coefficient was 0.9991. The relative standard deviation for seven replicate measurements of nickel was 7.6%. The relative recoveries in tap and well waters at the concentration level of 50 μg/L of Ni2+ were 92.8 and 91.6%, respectively. The proposed method was successfully applied in the analysis of different water samples and good spiked recoveries were obtained. HLLME-FA combined with GFAAS is a fast, simple and efficient method for the determination of Ni(II) in different water samples.