PRECONCENTRATION AND ATOMIC-ABSORPTION DETERMINATION OF IRON BY SEQUENTIAL INJECTION-ANALYSIS

A sequential injection analysis (SIA) assembly for the atomic absorpti on determination of Fe(III) in natural waters is proposed. Iron is pre concentrated on a microcolumn packed with a chelating resin (Chelex 10 0) that is inserted in the manifold. The sample is passed through the column and the iron retained by the resin is subsequently eluted with 2 M HNO3. The proposed SIA system affords automatic preconcentration, elution, detection of Fe(III), data acquisition and treatment. When 9 ml of iron solution containing 0.4 or 1 mg l(-1) was passed through th e resin, the retention efficiency was 93.1 +/- 0.6 and 7.4 +/- 3.0% re spectively, and when 27 ml of iron solution of 0.2 mg l(-1) was precon centrated, the retention was 8.4 +/- 2.9%. The detection limits thus a chieved is 12 mu g l(-1) when 9 ml of sample are preconcentrated and 6 mu g l(-1) for 27 ml. (C) 1997 Elsevier Science B.V.