Chelating resin sorption followed by supercritical fluid extraction and liquid chromatographic determination of aluminum in liquid samples

To determine aluminum content in liquid samples, a method combining the techniques of chelating resin sorption and supercritical fluid extraction (SFE) was described. The chelating resin highly selective for aluminum at pH < 3 was prepared by impregnating Chromazural S (CAS) on Amberlite IRA-400. The sorbed aluminum was extracted with supercritical CO2 containing trifluoroacetylacetone (TFA). A 45 factorial design was conducted for the simultaneous determination of various analytical SFE parameters including temperature, pressure, CO2 density, extraction time, and fluid flow rate. After removing excess TFA with NaOH (0.1 M), the extract was analyzed by HPLC with UV detection at 296 nm. We also demonstrated that the interference from iron complex in the applied liquid sample was negligible in this procedure. The aluminum content in Oolong tea determined by our method, 1.46 and 1.10 ppm in the first and second infusion, respectively, was successfully verified by spectrophotometry. The established method was also applied to determine the aluminum content in beer, Coca Cola, and orange juice. (C) 2003 Elsevier B.V. All rights reserved.