On-line preconcentration system for cobalt determination in bee honey using flow injection-flame AAS

A methodology for the on-line preconcentration and determination of cobalt by flame atomic absorption spectrometry (FAAS) coupled with flow injection (FI) in bee honey samples is proposed. For the retention of cobalt, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADA-P) complexing reagent, and Amberlite XAD-7 resin were used, at pH 9.5. The Co-(5-Br-PADAP) complexes were completely removed from the column with ethanol. An enrichment factor (EF) of 50-fold for a sample volume of 50 mL was obtained. The detection limit (DL) for the preconcentration of 50 mL of aqueous solution was 0.18 mug L-1. The precision for 10 replicate determinations at the 10 mug L-1 cobalt levels was 3.6% relative standard deviation (RSD), calculated with peak heights obtained. The calibration graph using the preconcentration system for cobalt was linear with a correlation coefficient of 0.9997 at levels near the DL, up to at least 300 mug L-1. The method was successfully applied to determination of total cobalt in honey samples.