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.

In this work, the direct determination methodology of glyphosate and aminomethylphosphonic acid (AMPA) by high performance liquid chromatography (HPLC) using inductively coupled plasma with triple quadrupole mass spectrometer (ICP-MS/MS) was compared with the conventional method using diode array detector (HPLC-DAD). Both methods were selective, but the chromatographic analysis using ICP-MS/MS as detector was four times faster than DAD. The methodology using ICP-MS/MS as detector was linear from 27 to 218 µg L-1, while by the conventional method it was 1 to 8 mg L-1. Detection limits of the glyphosate achieved with the HPLC-ICP-MS/MS and HPLC-DAD methods were 8.2 and 300 µg L-1, respectively. The direct determination using ICP-MS/MS as detector showed a lower number of stages in sample preparation because it did not need the derivatization step. Seven real samples were analyzed by HPLC-ICP-MS/MS and the results showed that these analytes were not detected.

Nesse artigo, a técnica de extração sólido-líquido com purificação em baixa temperatura para a determinação de nove clorobenzenos (CB) em lodo de esgoto foi otimizada, validada e aplicada. Análises foram realizadas por cromatografia gasosa acoplada ao espectrômetro de massas. Depois da otimização da fase extratora, um planejamento fatorial foi usado para avaliar a influência de três variáveis, as quais foram pH, força iônica (NaCl) e tempo de homogeneização. O método mostrou ser seletivo, com limites de detecção e quantificação menores que 4,1 e 12,5 µg kg-1, respectivamente. As porcentagens de extração foram cerca de 70% e o desvio padrão relativo menor que 13% para os nove clorobenzenos analisados. Durante o monitoramento mensal os compostos 1,4-CB; 1,2,4-CB e 1,2,3-CB foram detectados em amostras de lodo de esgoto. Somente o composto 1,2,3-CB foi quantificado em concentrações superiores ao limite máximo aceitável para clorobenzenos em solos agrícolas condicionados com lodo de esgoto, mas sem considerar o efeito de diluição do lodo no solo

In this paper, the technique of solid-liquid extraction with purification at low temperature for the determination of nine chlorobenzenes (CB) in sewage sludge was optimized, validated and applied. Analyses were carried out by using gas chromatography coupled with mass spectrometry. After univariate optimization of the extraction phase, a factorial design was used in order to evaluate the influence of pH, ionic strength (NaCl) and homogenization time. The method proved to be selective, with detection and quantification limits less than 4.1 and 12.5 µg kg-1, respectively. Recoveries were about 70% and the relative standard deviation was less than 13% for the chlorobenzenes analyzed. During the monthly monitoring of sewage sludge samples 1,4-CB, 1,2,4-CB and 1,2,3-CB were detected. Only 1,2,3-CB was quantified in concentrations higher than the maximum acceptable limit for chlorobenzenes in agricultural soils amended with sewage sludge disregarding the dilution effect of the sludge on soil.