Determination of lead by on-line solid phase extraction using a PTFE micro-column and flame atomic absorption spectrometry

A rapid and sensitive time-based flow injection (FI) method for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS), using polytetrafluoroethylene (PTFE) turnings as packing material in a micro-column, has been developed. The sample was mixed on-line with ammonium pyrrolidine dithiocarbamate (APDC) and the non-charged Pb(II)–PDC complex was absorbed quantitatively on the hydrophobic PTFE material, at a pH range 1.4–3.2. The preconcentrated complex was effectively eluted with isobutyl methyl ketone (IBMK) and introduced into the nebulizer-burner system. A nested coil (NC) is proposed for parking the eluate temporarily, in order to enable different elution and nebulization flow rates. With 180 s preconcentration time the sample frequency was 15 h−1, and the enhancement factor was 330 at 13.0 ml min−1 sample flow rate. The detection limit was cL=0.8 μg l−1, the relative standard deviation (R.S.D.) 2.6% at the 30 μg l−1 level and the calibration curve was linear over the concentration range 1.6–100 μg l−1. The proposed method was evaluated by analyzing certified reference materials of water, sediments and fish tissue. Finally, it was applied successfully to the analysis of various environmental samples.