Pre-concentration of cadmium from environmental samples by an alga and analysis by graphite furnace atomic absorption spectrometry

Abstract

A pure algal strain (Stichococcus bacillaris) is utilised to pre-concentrate Cd ions from fresh water and marine reference samples. This pre-concentration is achieved by mixing 10 mg of freeze-dried alga with 100 ml of a Cd containing solution and subsequent separation by centrifugation. The alga pellet is then suspended in 1 ml of solution and analysed as a slurry by graphite furnace atomic absorption spectrometry. The removal and pre-concentration of Cd from a riverine reference water sample (SLRS-1) demonstrated the analytical utility of this alga. Pre-concentration of Cd from the two sea water samples, CASS-1 (near shore sea water) and NASS-2 (open ocean sea water), was not possible with this algal strain due to the high salinity of these solutions. The concentration of Cd in the riverine sample was determined to be 16.6 ± 1.9 ng l–1, which is in good agreement with the certified value of 15 ± 2 ng l–1. The time necessary for the pre-concentration of six samples is less than 20 min, which amounts to less than 4 min per sample.