Mercury determination by FI-CV-AAS after the degradation of organomercurials with the aid of an ultrasonic field: The important role of the hypochlorite ion

Due to new findings, the methodology based on room-temperature ultrasonic irradiation (sonolysis) for conversion of organomercurials into inorganic mercury [J.L. Capelo, I. Lavilla, C. Bendicho, Anal. Chem. 72 (2000) 4979–4984.] is further investigated. Inorganic mercury is selectively determined by Flow Injection-Cold Vapour Atomic Absorption Spectrometry (FI-CV-AAS) using SnCl2/HCl. Complete oxidation of methyl-mercury can be accomplished within 90 s whilst phenyl and diphenyl-mercury can be degraded within 10 s using a 50% sonication amplitude (100 W nominal power) provided by a probe ultrasonic device (20.5 kHz frequency) and a 1 mol L−1 HCl liquid medium with the presence of hypoclorite ion. The importance of hypochlorite in reduction of organomercurials by stannous chloride is highlighted. Oxidation kinetics indicated a pseudo first-order reaction for methyl-mercury, phenyl-mercury, and dipheny-mercury.