Determination of trace quantity of aluminium in dialysate concentrates using solid phase and cloud point extraction methods

Abstract

A new method is reported for the separation of aluminium ions (Al³⁺) from interfering cations in dialysis concentrate solutions (DS) through solid phase extraction (SPE) using 2-methyl-8-hydroxyquinoline (2-MHQ). While separated Al³⁺ was preconcentrated by cloud point extraction (CPE) using 8-hydroxyquinoline (8-HQ) as complexing reagent, the resulting complex was entrapped in non-ionic surfactant (Triton X-114). Then fluorescence intensity of the Al³⁺-8-HQ complex was measured by spectrofluorimetry and the results were compared with those obtained by flame atomic absorption spectrometry. The chemical variables affecting the analytical performance of the CPE were studied and optimized. The validity of methodology was checked by the standard addition method, under optimum experimental conditions >98% recovery of Al³⁺ was obtained. The enrichment factor and detection limit of Al³⁺ for the preconcentration of 50 ml of DS were found to be 200 and 0.384 μg L⁻¹, respectively. The relative standard deviation for six replicate determinations of Al³⁺ at a concentration level of 50 μg L⁻¹ for both techniques was <6%. The effect of different interferent species was also studied. The proposed method has been applied for the determination of trace amount of Al³⁺ in DS samples with satisfactory results. The concentration of Al³⁺ in DS was observed in the range of 15.2–43.8 μg L⁻¹, which is above the permissible limit.