A cloud point extraction (CPE) method for the preconcentration of trace aluminum prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS) has been developed. The CPE method is based on the complex of Al(III) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), and then entrapped in non-ionic surfactant Triton X-114. PMBP was used not only as chelating reagent in CPE preconcentration, but also as chemical modifier in GFAAS determination. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of PMBP and Triton X-114, equilibration temperature and time, were investigated in detail. An enrichment factor of 3 7 was obtained for the preconcentration of Al(III) with 10 mL solution. Under the optimal conditions, the detection limit of this method for AI(III) is 0.09 ng mL(-1), and the relative standard deviation is 4.7% at 10 ng mL(-1) Al(III) level (n = 7). The proposed method has been applied for determination of trace amount of aluminum in biological and water samples with satisfactory results. (c) 2007 Elsevier B.V. All rights reserved.