Optimization of Methodology for Determination of Inorganic Chromium Species in Sewage Sludge Samples by HPLC-ICP-MS/MS


J. Braz. Chem. Soc.




This study developed a methodology for extracting and speciating CrIII and CrVI in sewage sludge by high performance liquid chromatography, inductively coupled plasma tandem mass spectrometry (HPLC-ICP-MS/MS). The optimal procedure was solid-liquid extraction in a water bath with stirring at 50 °C for 16 h and 50 mmol L−1 ethylenediaminetetraacetic acid (EDTA) extraction phase at pH 9.5. In the validated method, the recovery in the fortification experiment was greater than 70% and the relative standard deviation was less than 7%. Speciation analyses showed that all CrVI was spontaneously reduced to CrIII in the sludge sample. The limits of detection and quantification were 0.060 and 0.20 µg L−1, respectively, and the analyses of CrIII by means of ICP-MS/MS were linear from 0.20 to 50 µg L−1. The extraction efficiency of Cr specie in this validated method improved from 4.09 to 53.3% compared to the EPA 1311 method. The methodology was successfully applied to quantify CrIII in a sludge sample with a lower concentration than that established by European legislation 80568/4225/91.

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