Micellar extraction followed by flow injection ICP-AES for preconcentration and determination of aluminium ions

In this study, a convenient and sensitive off-line cloud point extraction method (off-line CPE) was developed to preconcentrate trace amounts of aluminium (Al) ions prior to their determination by flow injection (FI) coupled to inductively coupled plasma-atomic emission spectrometry (ICP-AES). The method is based on the formation of a complex between Al³⁺ and 3, 2', 4', 5, 7-penta hydroxy flavone reagent, using Triton X-114 as a non-ionic surfactant to extract the formed complex and facilitate phase separation. Following extraction, the micellar phase containing Al ions was analyzed using ICP-AES coupled with a flow injection system (FI-ICP-AES). The off-line CPE variables were optimized using the Taguchi method, resulting in optimal conditions of pH 4.5, 1000 µg L^-1 reagent, 0.1% (w/v) Triton X-114, 0.25 mol L^-1 salt concentration, and an equilibrium temperature of 60 °C. Under these conditions, a linear calibration range of 1.0-500 µg L^-1 was achieved for determination of Al ions, with a detection limit (DL) of 0.89 µg L^-1, an enhancement factor of 54.7, and a relative standard deviation (RSD) below 3.1%. The accuracy and applicability of the proposed off-line CPE/FI-ICP-AES method were evaluated by analyzing Al ions in various aqueous samples, yielding satisfactory and reliable results.