Flow injection determination of cobalt after its sorption onto polyurethane foam loaded with 2-(2-thiazolylazo)-p-cresol (TAC)

This paper reports the development of a new methodology for determination of cobalt in water samples by using a flow injection system with loaded PUF as solid phase to preconcentrate analytes. Procedure is based on on-line retention of Co(III) ions (generated in alkaline medium by Co(II) oxidation) in a minicolumn packed with a polyether type polyurethane foam loaded with TAC (2-(2-thiazolylazo)-p-cresol) and elution with 2 mol l−1 HCl directly to the flame atomic absorption spectrometer nebulizer. Several chemical and flow variables that could affect the performance of this system were investigated as well as the possible interferents. For 2 min of preconcentration time (10.0 ml of sample volume) the system achieved a detection limit 3.2 μg l−1, a R.S.D. 5% at 20 μg l−1 and an analytical throughput 24 h−1. Whereas for 3 min of preconcentration time (15.0 ml of sample volume) a detection limit 2.4 μg l−1, a R.S.D. under 8% at 10 μg l−1 and a sampling frequency 17 h−1 were reported.