In-line concentration on chitosan and the use of 2,2 '-dipyridyl-2-pyridylhydrazone for the flow-injection spectrophotometric determination of lead

A flow-injection system with spectrophotometric detection involving the in- line concentration was developed for lead determination in natural water sa mples. Lead concentration was carried out in a mini-column packed with nove l stuff chitosan, and sorption occurred at pH=6 - 9. The amount of lead flo wing through the chitosan was controlled by time, the CTAB surfactant was p assed through a mini-column and a 0.2 M NaOH stream was used as the eluent. The eluted lead merged with 2,2'-dipyridyl-2-pyridylhydrazone (DPPH) reage nt synthesised in the author's lab and with a berate solution; complex form ation took place at pH 11 - 12 inside a following reactor and monitoring wa s carried out at 468 nm. The detection limit was 0.13 mu g l(-1) and, the s ample throughput was 25 h(-1). The accuracy was assessed by running spiked river-water samples.