Determination of total and inorganic mercury in fish samples with on-line oxidation coupled to atomic fluorescence spectrometry

An atomic fluorescence spectrometry system for determination of total and inorganic mercury with electromagnetic induction-assisted heating on-line oxidation has been developed. Potassium peroxodisulphate was used as the oxidizing agent to decompose organomercury compounds. Depending on the temperature selected, inorganic or total mercury could be determined with the same manifold. Special accent was put on the study of the parameters influencing the on-line digestion efficiency. The tolerance to the interference of coexisting ions was carefully examined in this system. Under optimal conditions, the detection limits (3σ) were evaluated to be 2.9 ng l−1 for inorganic mercury and 2.6 ng l−1 for total mercury, respectively. The relative standard deviations for 10 replicate determinations of 1.0 μg l−1 Hg were 2.4 and 3.2% for inorganic mercury and total mercury, respectively. The proposed method was successfully applied to the determination of total and inorganic mercury in fish samples.