Effervescence-assisted Dispersive Liquid-liquid Microextraction for Trace Analysis of Co(II) and Ni(II) from Aqueous Sample Based on Phthalic Acid as a Complexing agent and Co-disperser

A green effervescence-assisted dispersive liquid-liquid microextraction based on phthalic acid, as a complexing agent and co-disperser, coupled with graphite furnace atomic absorption spectrometry has been developed for the extraction and preconcentration of Co(II) and Ni(II) from aqueous samples. Initially two test tubes were selected. A specified amount of sodium bicarbonate is placed at the bottom of the first conical and dried glass test tube, and then μl-level of 1,1,2,2-tetrachloroethane as an extraction solvent is added. Phthalic acid (as a complexing agent) is added to the aqueous solution placed in the second tube to form phthalate-metal complexes. Then, the content of the second tube is added into the first tube. A reaction between the excess amount of phthalic acid and sodium bicarbonate is immediately occurred, and the produced CO2 leads to dispersion of the extraction solvent as tiny droplets. In this study, phthalic acid is used simultaneously as a complexing agent and co-disperser. Under the optimum conditions the calibration curves were linear in the ranges of 25.0-1000.0 and 50.0-1000.0 ng l-1 for Co(II) and Ni(II), respectively. The detection limits were obtained 9.2 and 15.0 ng l-1 for Co(II) and Ni(II), respectively. Extraction recoveries were 99 and 98% for Co(II) and Ni(II), respectively. Enrichment factors were obtained 197.8 and 196.4 for Co(II) and Ni(II), respectively. The relative standard deviations were ≤1.3% for intra- (n = 6) and ≤3.0 for inter-day (n = 6) precisions. Finally, the proposed method was successfully applied for the simultaneous analysis of the analytes in environmental water and fruit juice samples.