On-line preconcentration employing a tannin resin for copper determination in plant material and food stuff by atomic absorption spectrometry

a flow system for copper on-line preconcentration, employing a tannin resin prepared from eucalyptus saligna sm, with determination by flame atomic absorption spectrometry is proposed. the manifold was designed by assembling an automatic injector-commutator and a set of three-way solenoid valves which were controlled by a microcomputer with a pcl-711 interface card running a software written in quickbasic 4.5. the analyte was concentrated by pumping the sample solution through the resin column during 60 s, followed by elution with a 1.0 mol l-1 hydrochloric acid solution. accuracy was assessed by analyzing acidic digests of certificate reference materials and no significant difference at 95% confidence level was observed. other profitable features such as throughput of 48 determinations per hour, reagent consumption of 67 ml per determination, relative standard deviation of 3% (n=10) for a typical sample presenting concentration of 21.75 ng ml-1 cu, detection limit of 1 ng ml-1 and enrichment factor of 10 times were also achieved.