Determination of mercury in filtered sea-water by flow injection with on-line oxidation and atomic fluorescence spectrometric detection

Abstract

A flow injection (FI) atomic fluorescence method incorporating an on-line bromide–bromate oxidation step to determine mercury in filtered sea-water samples at the ng l^–1 level is described. A heated reaction coil was incorporated in the FI manifold to increase the conversion of organic mercury into inorganic mercury(II) chloride from 50 to approaching 100%. Detection limits (3σ) for mercury(II) chloride and methylmercury chloride were 25 and 23 ng l^–1 Hg, respectively. The FI manifold could also be used to determine the total mercury concentration in biological materials and was validated by analysing the CRM TORT-1 Lobster Hepatopancreas. Good agreement with the certified (330 ± 60 µg l^–1) value was achieved (353 ± 64 µg l^–1). The analysis of coastal water samples from Sutton Harbour, Plymouth, showed that mercury levels ranged from 24 ± 5 to 54 ± 10 ng l^–1.