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

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 (3 sigma) 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 mu g l(-1)) value was achieved (353+/-64 pg 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).