On-line solid phase extraction system using PTFE packed column for the flame atomic absorption spectrometric determination of copper in water samples

A new flow injection on-line adsorption preconcentration system adapted to flame atomic absorption spectrometry (FAAS) for copper determination at the mug l(-1) level was developed. Polytetrafluoroethylene (PTFE) turnings pac ked in a mini-column were used as sorbent material. The copper ammonium pyr rolidine dithiocarbamate (APDC) complex was sorbed on the PTFE turnings, fr om which it could be eluted on-line instantly by isobutyl methyl ketone (IB MK) into the flame at a flow rate of 2.3 ml min(-1). The system was optimiz ed and offered good performance characteristics with practically unlimited life time, greater flow rates and improved flexibility, as compared with ot her sorbent materials and the knotted reactor preconcentration systems. Wit h 1 min preconcentration time, and a sample frequency of 40 h(-1), the enha ncement factor was 340, which could be further improved by increasing the p reconcentration time. The detection limit was c(L) = 0.05 mug l(-1), and th e precision was 1.5%, at the 2.0 mug l(-1) Cu level. The method has been ap plied successfully to the analysis of potable, river and seawater, and its accuracy was tested by the analysis of certified reference materials and by recovery measurements on spiked samples. No significant interferences exis t from other substances usually occurring in natural water. (C) 2001 Elsevi er Science B.V. All rights reserved.