The paper describes a highly sensitive and selective extraction spectrophotometric method for determination of aluminum in dialysis concentrates with new reagent 3,5-ditertbutylsalicylfluorone abbreviated as DTBSF, in which the ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate abbreviated as [C4tmsim][PF6] was used as novel medium for liquid/liquid extraction of aluminum(III). Under optimal condition, DTBSF reacted with aluminum(III) to form a neutral Al–DTBSF complex rapidly, the complex was then extracted into the [C4tmsim][PF6] phase, the absorbance of the complex in ionic liquid at 542nm was recorded and used to determine aluminum(III). The apparent molar absorptivity of the complex and detection limit were found to be 3.52×106lmol−1cm−1 and 0.06ÎŒg/l, respectively. The absorbance of the complex at 542nm increases linearly with the concentration of aluminum(III) up to 3ÎŒg of aluminum(III) in 250ml of aqueous solution. The interference study show the determination of aluminum is free from interferences of almost all positive and negative ions found in dialysis concentrate samples. The determination of aluminum in dialysis concentrates were carried out by the present method and electrothermal atomic absorption spectrometry (GTAAS). The results were satisfactorily comparable so that the applicability of the proposed method with the ionic liquid system was also investigated. Moreover, the synthesis of and conditions for the formation and extraction of Al–DTBSF complex were investigated as well.