Determination of bismuth in cod muscle, lake and river sediment by flow injection on-line 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 electrothermal atomic absorption spectrometry (ETAAS). The diethyldithiophosphate complex of bismuth is formed in 0.5–4% (v/v) HNO3 and adsorbed onto the inner walls of a PTFE knotted reactor. The complex is eluted with 30% (v/v) HCl and the eluate is directly introduced into a pyrolytically coated graphite tube without a preheating step. The ETAAS determination of the concentrated analyte is carried out in parallel with the next preconcentration cycle. An enhancement factor of 74 and a detection limit (3σ) 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 μg l−1 (n=9). The analytical results for the Community Bureau of Reference (BCR) CRMs 280 (lake sediment) and 320 (river sediment) were in good agreement with the indicative values for the bismuth content. For the BCR CRM 422 (cod muscle) a value of 14 ng g−1 was found.