Application of 5,10,15,20-tetrakis(4-carboxyphenyl)porphine for cadmium preconcentration in flow-injection system

The suitability of 5,10,15,20-tetrakis(4-carboxyphenyl)porphine as a complexing agent for the on-line preconcentration of cadmium using an anion exchanger (Amberlite IRA-904) in a microcolumn has been tested. Various parameters which affect complex formation and its sorption, as well as elution into the nebulizer of flame atomic absorption spectrometry (FAAS), were optimized. A 5 x 10(-4) mol l(-1) reagent was on-line mixed with an aqueous sample solution and flowed through the microcolumn for 2 min. The sorbed complexes were then eluted with 2 mol l(-1) of nitric acid into the nebulizer of FAAS. A good precision (2.1% RSD for 40 mug l(-1) cadmium) and a high enrichment factor (36) with a detection limit (3sigma) of 1.4 mug l(-1) were obtained. The achieved analytical results for a standard reference material (SRM 1643d) were in good agreement with the certified values.