A flow injection system with four ion exchange resin columns for cadmium pre-concentration and determination by flame AAS

A flow injection system comprised of four mini-columns packed with cation exchange resin was designed to implement an on-line pre-concentration procedure for cadmium determination by flame atomic absorption spectrophotometry. The AG50W-X8 resin behavior in the flow system was studied, talking into account its suitability for application to routine analysis. A throughput of up to 80 determinations per hour, and a detection limit of 0.7 ng/L were achieved. The relative standard deviation of measurements (n=10) for a sample with 20.0 g Cd/L was lower than 2%. By applying the t-test at a probability level of 5% no significant was observed in comparing the results obtained by the proposed method and the certified values of standard reference materials. (author)