Preconcentration of Cobalt(II) and Nickel(II) on Chitin as 1-Nitroso-3, 6-disulfo-2-naphtholato Complexes and Their Determination by Tungsten Metal Furnace Atomic Absorption Spectrophotometry with Direct Injection of Chitin/Water Suspension

Abstract

Preconcentration of cobalt(II) and nickel(II) as the 1-nitroso-3, 6-disulfo-2-naphtholato [nitroso R (NR)] complexes onto chitin powder has been applied to the sub-μg/l level determination of their ions in water samples by tungsten metal furnace atomic absorption spectrophotometry. The cobalt(II) and nickel(II) as NR complexes (Co•NR, Ni•NR) were quantitatively adsorbed onto chitin at pH 4.0-6.0 for Co•NR and pH 5.0-7.0 for Ni•NR. The Co•NR and Ni•NR adsorbed chitin was separated from the sample solution by membrane filtration, then dispersed in water. The resulting suspensions were injected directly into the tungsten metal furnace. The detection limit (S/N=3) for cobalt(II) was 0.02μg/500cm3 and that for nickel(II) was 0.03μg/500cm³.