Comparison of two digestion procedures for the determination of lead in lichens by electrothermal atomic absorption spectrometry |
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| Affiliation: | 1. Laboratory of Toxicology, CESTEH/ENSP/Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil;2. DSSA/ENSP/Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil;1. Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C-3P8, Canada;2. Laboratory of Science and Technology of Environment, University of Constantine-1, Algeria;3. Department of Materials Engineering, University of Science and Technology, Oran, Algeria;4. Laboratory of Materials Chemistry, Oran University, BP 1524 El M’naouer, Oran, Algeria;5. Laboratory, Mechanical Engineering Department, École de Technologie Supérieure, H3C 1K3, Canada;1. Department of Chemistry, Indian Institute of Technology (Banaras Hindu University) Varanasi, Varanasi 221 005, India;2. DAE Raja Ramanna Fellow, Department of Chemical Engineering and Technology, Indian Institute of Technology (Banaras Hindu University) Varanasi, Varanasi 221 005, India;3. Department of Civil and Ecological Engineering, I Shou University, Kaohsiung 84008, Taiwan;1. Catalizadores y Superficies, INTEMA, Facultad de Ingeniería, UNMdP, J.B. Justo 4302, 7600 Mar del Plata, Argentina;2. LARSI, Dep. Industrias, FCEyN, Universidad de Buenos Aires, Int. Güiraldes 2620, C1428BGA Buenos Aires, Argentina;1. School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China |
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| Abstract: | The efficiency of two procedures for the digestion of lichen was investigated using a heating block and a microwave oven. In the open vessels, concentrated nitric acid was added to the samples, left for 1 h, and the addition of 30% (v / v) hydrogen peroxide completed the digestion. In the closed system, the complete digestion was performed using concentrated nitric acid and hydrogen peroxide, reducing the amount of chemicals, time and contamination risk. Both digestion methods gave comparable results, and recoveries were statistically not different. For a lichen sample spiked with 10 μg Pb, the recovery was 111% and 110% using microwave and heating block digestion, respectively, while it was 100% and 103% for a 100 μg Pb spike. For the determination by electrothermal atomic absorption spectrometry samples were diluted 20 times with water and a volume of 20 μL was injected into the graphite furnace without chemical modifier. Pyrolysis and atomization temperatures of 700 °C and 1500 °C, respectively, were used. The characteristic mass was 8.4 ± 0.6 pg for aqueous calibration solutions and 8.9 ± 0.8 pg for samples. Calibration was against matrix matched standards. The recovery test showed some contamination problem with the lowest concentrations in both procedures. The detection limits were 4.4 μg L− 1 with microwave oven and 5.4 μg L− 1 with the heating block in the undiluted blank. |
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