A separation-preconcentration procedure was developed for the determination of trace amounts of aluminium in water samples and dialysis concentrates by UV-vis Spectrophotometry after coprecipitation using 8-hydroxyquinoline (8-HQ) as a chelating agent and Co(II) as a carrier element. This procedure is based on filtration of the solution containing precipitate on a cellulose nitrate membrane filter following aluminium(III) coprecipitation with Co/8-HQ and then the precipitates together with membrane filter were dissolved in concentrated nitric acid. The metal contents of the final solution were determined by UV-vis Spectrophotometry with Erio Chrome Cyanine-R standard method. Several parameters including pH of sample solution, amount of carrier element and reagent, standing time, sample volume for precipitation and the effects of diverse ions were examined. The enrichment factor was calculated as 50 and the detection limits, corresponding to three times the standard deviation of the blank (N: 10), was found to be 0.2 mu g L-1. The accuracy of the method was tested with standard reference material (CRM-TMDW-500) and spiked addition. Determination of aluminium(III) was carried out in sea water, river water, tap water and haemodialysis fluids samples. The recoveries were >95%. The relative standard deviations of determination were less than 6%. (C) 2010 Elsevier B.V. All rights reserved.