Flotation spectrophotometric determination of aluminum with alizarin

Aluminium was determined in a weakly alkaline medium by reaction with alizarin at trace level. Flotation of the complex was carried out with heptane, followed by dissolution in N,N-dimethylformamide (DMF) for subsequent spectrophotometric determination. The molar absorptivity was 2.92x10(5) mol(-1) cm(-1) at 518 nm. Beer's law was obeyed in the range 5-80 mu g/l and the detection limit was 0.4 mu g/l. The reliability of the procedure was confirmed by determination of a sample of milk with Graphite Furnace Atomic Absorption Spectrophotometric method (GFAAS). The precision and accuracy of the method were both acceptable via F and t tests at the 95% confidence level.