On-line flow injection flame AAS determination of cobalt in soil and sediment samples with 5,7-dichloroquinoline-8-ol-embedded polymeric materials

Abstract

Dichloroquinoline-8-ol-embedded styrene-ethylene-glycol dimethacrylate polymer materials were pepared via the bulk, preciptation and suspension polymerization methods using similar compositions. the polymerization was carried out by thermal means in the presence of 2,2'-azobisisobutyrontrile as initiator and 2-methoxy ethanol as porogen. the above synthesizes polymer materials were characterized physically and morphologically by using the FTIR, TGA, CHN, and SEM techniques. These polymeric materials were packed into homemade micro columns and used for on-line solid phase extraction (SPE) preconcentration of trace amounts of cobalt. The preconcentrated cobalt species were eluted with 0.01 mol L-1 of nitric acid and injected directly into the nebulizer of a flame atomic absorption spectrometer (FAAS) for quantification.

The enrichment factors for bulk, precipitation and suspension polymerization materials were 12.5, 12.5, and 6.0, respectively, with a 1-min preconcentration time and a sample throughput of 30 h(-1). The detection limits crresponding to 3 times the standard deviation of the blank were founf to be 10, 10, and 80 mu g L-1 with a precision of 2.1, 2.5, and 2.6% (RSD) for five successive determinations of 80 mu g L-1 of cobalt.

Furthermore, the retention capacities determined by the batch method were 11.46, 11.42, and 8.52 mg of Co(II) per g of bulk, precipitation, and suspension poymerization materials, respectively. Thus, enrichment factor, detection limit, and retention capacities are in the order: precipitation - bulk > suspension. No significant interference was observed from neutral electrolytes and 100-fold amounts of Fe(III), Ni(II), Mn(II), Cu(II), and Zn(II). In addition to testing the accuracy of the devoloped procedure for the determination of cobalt in certified reference materials of soil and marine sediments, the method was applied successfully to the determination of cobalt in real soil and sediment samples.