Column preconcentration of aluminum using eriochrome cyanine R and methyltrioctylammonium chloride adsorbent supported on naphthalene with subsequentspectrophotometric determination

A sensitive and rapid method for preconcentration of aluminum has been deve loped by using naphthalene-methyltrioctylammonium chloride (Aliquat-336s) a dsorbent. Aluminum ion forms a complex with Eriochrome cyanine R that is re tained by the adsorbent in the column at pH 6 with a how rate of 1 ml min(- 1). The metal complex and naphthalene adsorbent are completely dissolved ou t of the column with 5 mi of a N,N-dimethylformamide (DMF) and acetic acid mixture (2:1) and the absorbance is measured at 557 nm. The calibration gra ph is linear in the range 0.1-10 mu g of aluminum in 5 ml of final DMF and acetic acid mixture, and the detection limit is 0.01 mu g ml(-1). A relativ e standard deviation of 1.6% is obtained for eight replicate determinations of 5 mu g of aluminum. The proposed method was applied to the determinatio n of aluminum in certified reference material. (C) 1999 Academic Press.