FLOW-INJECTION PRECONCENTRATION OF CO(II) ON 1-NITROSO-2-NAPHTHOL-3,6-DISULFONATE-MODIFIED ALUMINA FOR FLAME ATOMIC-ABSORPTION SPECTROMETRY

The possibility of using alumina loaded with 1-nitroso-2-naphthol-3,6- disulphonate for the on-line preconcentration of cobalt(II) was invest igated. The relatively high capacities of this simply and reproducibly prepared material and the absence of swelling complications allow for its effective use in a flow-injection analysis-atomic absorption spec trometric system. In the time-based system with a 20-min preconcentrat ion time a detection limit of 0.44 mu g l(-1) was obtained with a prec ision of 2.3% (R.S.D.) at the 10 mu g l(-1) level. A 97% recovery was obtained for artificial ocean water spiked with 1 mu g l(-1) of Co(II) . The method was applied to the determination of cobalt in oriental to bacco leaves certified standard material.