Evaluation Of Dmit [4,5-dimercapto-1,3-dithyol-2-thionate] As Chelating Agent In A Cloud Point Extraction Procedure For Pb2+ Determination In Water Samples [avaliação Do Dmit [4,5-dimercapto-1,3-ditiol-2-tionato] Como Agente Complexante Em Um Procedimento De Extração Por Ponto Nuvem Para Determinação De Pb2+ Em Amostras De água]

The present study proposes a new method for cloud point preconcentration of Pb2+ ions based on complex formed with [4,5-dimercapto-1,3-dithyol-2-thionate] and posterior determination by flame atomic absorption spectrometry (FAAS). The preconcentration of Pb2+ was carried at pH 5.0 under following conditions: time and temperature of batch at 15 min. and 70oC, respectively, 0.1% (v/v) Triton X-114, 0.003 mol L-1 acetate/acetic acid buffer solution, 1.0 x 10-5 mol L-1 DMIT and 0.5% (m/v) NaCl. Under the best analytical conditions the method provided a limit of detection of 2.85 μg L-1 by preconcentrating 10.0 mL of sample and calibration curve ranging from 0 up to 650 μg L-1 (r = 0.99945). 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