DETERMINATION OF BISMUTH IN COD MUSCLE, LAKE AND RIVER SEDIMENT BY FLOW-INJECTION ONLINE SORPTION PRECONCENTRATION IN A KNOTTED REACTOR COUPLED WITH ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A selective and robust flow injection (FI) on-line sorption separation and preconcentration procedure was developed for the determination of bismuth in cod muscle, lake and river sediment samples by electrother mal atomic absorption spectrometry (ETAAS). The diethyldithiophosphate complex of bismuth is formed in 0.5-4% (v/v) HNO3 and adsorbed onto t he inner walls of a PTFE knotted reactor. The complex is eluted with 3 0% (v/v) HCl and the eluate is directly introduced into a pyrolyticall y coated graphite tube without a preheating step. The ETAAS determinat ion of the concentrated analyte is carried out in parallel with the ne xt preconcentration cycle. An enhancement factor of 74 and a detection limit (3 sigma) of 3 ng l(-1) along with a sampling frequency of 28 h (-1) were achieved with a 60 s loading time at a sample flow rate of 5 .2 ml min(-1). The relative standard deviation was 3.4% for 0.1 mu g l (-1) (n=9). The analytical results for the Community Bureau of Referen ce (BCR) CRMs 280 (lake sediment) and 320 (river sediment) were in goo d agreement with the indicative values for the bismuth content. For th e BCR CRM 422 (cod muscle) a value of 14 ng g(-1) was found. (C) 1997 Elsevier Science B.V.