Evaluation of Different Modifiers for the Determination of Arsenic in Leachate Samples from Sanitary Landfills by Electrothermal Atomic Absorption Spectrometry

摘要

The aim of the present work was to develop and validate a rapid and accurate method of arsenic determination in leachate samples by electrothermal atomic absorption spectrometry. Leachate samples from sanitary landfills are considered difficult samples to analyze due to severe matrix interferences. A comparative study of various chemical modifiers was performed: Pd, Mg, Au, Pt, Ru, Rh, Ir, C _6H _8O _7 (citric acid), Pd + Mg, Ir + Mg, and the permanent modifier Zr - Ir.Among the modifiers tested, the mixture 5 μg Ir + 40 μg Mg provided the best performance, followed by the permanent modifier Zr - Ir (a coating of 200 μg Zr + 20 μg Ir). The permanent modifier was finally chosen due to the decreased background signal and sufficient sensitivity.In order to investigate the presence of matrix interference and exploit the possibility of performing calibrations by simple aqueous solutions, calibration with aqueous standards, matrix matched standards and with standard additions was performed. It was observed that, in the presence of the Zr - Ir permanent modifier, the slopes of the calibration curve and the matrix-matched/standard addition curves were statistically different (checked by t-test). The recoveries from matrix-matched calibrations for three concentration levels were ranged between 96.4% and 100%. Precision experiments were also performed and the relative standard deviation (%RSD) for four different concentrations was ≤10%. The method was applied to the determination of arsenic in leachate samples collected in the solid waste sanitary landfill of Ano Liossia, Attika, Greece.