Determination of total and inorganic mercury in biological and environmental samples with on-line oxidation coupled to flow injection-cold vapor atomic absorption spectrometry

A method for determination of inorganic and total mercury by flow injection-cold vapor atomic absorption spectrometry (FI-CVAAS) with on-line oxidation was developed. Potassium peroxodisulphate and sulphuric acid were used as oxidizing agents so that decomposition of organomercury compounds could be achieved. Depending on the temperature selected, inorganic or total mercury could be determined with the same FI manifold. In order to assess the method performance, synthetic wastewater, wastewater, urine and saline water samples were spiked with inorganic mercury, methylmercury and phenylmercury. Quantitative recoveries were obtained for the three mercury species, except with the synthetic wastewater when the chemical oxygen demand value was higher than 1000 mg l^?1. In most cases, the standard addition method was usually needed for calibration. LODs calculated as 3 σ/m were 0.47 μg l^?1 for inorganic mercury and 0.45 μg l^?1 for total mercury. R.S.D. values corresponding to peak height measurements were 1.5 and 2.2% for inorganic mercury and total mercury, respectively. The accuracy of the method was tested by analyzing 5 mol l^?1 hydrochloric acid extracts of seven biological and environmental CRMs. LODs in the solid CRMs ranged from 0.032 to 0.074 μg g^?1.