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Ren Z.-J.,Pinggu Environmental Monitoring Station | Hao G.-Q.,Control Iron and Steel Research Institute, China | Yin C.-T.,Pinggu Environmental Monitoring Station | Zhang M.-J.,Pinggu Environmental Monitoring Station | And 2 more authors.
Yejin Fenxi/Metallurgical Analysis | Year: 2014

After the sample was digested with high-pressure sealed microwave digestion technology, a method for determination of mercury and arsenic in sludge from sewage treatment plants was established by hydride generation atomic fluorescence spectrometry. The digestion acid and the digestion procedure were optimized and the influence of potassium borohydride concentration on the determination was discussed. The results showed that 0.25 g of the sludge samples could be completely digested with 10 mL of mixed acid of nitric acid and hydrochloric acid (4+6). The digestion procedure was determined as follows: digestion power of 850 W and the emissivity of 80%, the temperature was raised within 5 min from room temperature to 110°C and kept for 5 min for the first step, and the temperature was further raised to 180°C within 10 min and kept for 20 min for the second step. When the potassium borohydride concentration was 20 g/L, the result was optimum. The detection limits of this method for mercury and arsenic were 0.0016 mg/kg and 0.0022 mg/kg, respectively. The method was applied to the determination of mercury and arsenic in sludge samples, the relative standard deviations (RSD, n=6) were 2.7%-3.8% and 1.1%-2.0%, respectively, and the recoveries for mercury and arsenic were 96%-102% and 98%-104%, respectively. When the method was applied to soil certified reference materials GSS-25 and GSS-26, the results were consistent with the certified values and the RSDs (n=6) for mercury and arsenic were 4.5%-7.4% and 2.2%-2.4 %, respectively.

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