DETERMINATION OF MERCURY IN FILTERED SEA-WATER BY FLOW-INJECTION WITHONLINE OXIDATION AND ATOMIC FLUORESCENCE SPECTROMETRIC DETECTION

A flow injection (FI) atomic fluorescence method incorporating an on-l ine bromide-bromate oxidation step to determine mercury in filtered se a-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 approa ching 100%. Detection limits (3 sigma) for mercury(II) chloride and me thylmercury chloride were 25 and 23 ng l(-1) Hg, respectively. The FI manifold could also be used to determine the total mercury concentrati on 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 c oastal water samples from Sutton Harbour, Plymouth, showed that mercur y levels ranged from 24+/-5 to 54+/-10 ng l(-1).