Flow injection on-line sorption preconcentration of platinum in a knotted reactor coupled with electrothermal atomic absorption spectrometry

A flow injection on-line sorption preconcentration method for the electrothermal AAS determination of platinum has been developed. The pyrrolidine dithiocarbamate complexes of either Pt4+ or Pt2+, formed in 0.7 mol L-1 HNO3, are on-line adsorbed on the inner walls of a PTFE knotted reactor and subsequently eluted with methanol. An enhancement factor of 112 and a detection limit (3 sigma) of 10 ng L-1 along with a sampling frequency of 21 h(-1) are achieved with a 90 s preconcentration time at a sample flow rate of 8.8 mt min(-1). The relative standard deviation is 2.5% for 0.4 mu g L-1 Pt. The method has been applied to the determination of platinum in blood samples.