Combination of Dispersive Liquid Liquid Microextraction and Emulsion Breaking for the Determination of Cu(II) and Pb(II) in Biodiesel and Oil Samples

Author(s)

Lima, Lucas C. ^[1] ; Paixao, Thiago R. L. C. ^[2] ; Nomura, Cassiana S. ^[2] ; Gaubeur, Ivanise ^[1]

Affiliation

^[1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Av Estados 5001, BR-09210971 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo - Brazil

• Document type: Journal article
• Source: ENERGY & FUELS; v. 31, n. 9, p. 9491-9497, SEP 2017.
• Web of Science Citations: 3

Abstract

Trace element determination in oil and biodiesel samples is not a simple task. To improve detectability and minimize the matrix effect, a preconcentration procedure before analysis is often required. In this work, we apply dispersive liquid-liquid microextraction to the determination of copper and lead in biodiesel and oil samples. The complexes formed between Cu(II), Pb(II), and di-2-pyridyl ketone salicyloylhydrazone were extracted using 1-undecanol as an extractant solvent and ethanol as a disperser solvent. The concentration of analytes was determined using graphite furnace atomic absorption spectrometry after matrix modification and Zeeman background correction. The complexant concentration, pH value, and extractant solvent volume were optimized using a multivariate consisting of a central composite design and a univariate analysis. Under optimum complexation and microextraction conditions (pH 9.2, 50 mu L of extractant, and 150,mu L of disperser solvent), calibration curves were obtained with linear ranges of 1.0-25 mu g L-1 (Cu(II)) and 1.0-40 mu g L-1 (Pb(II)) and limits of detection of 0.23 and 0.24 mu g L-1 for Cu(II) and Pb(II), respectively. Before microextraction, an emulsion-breaking procedure was applied in biodiesel and oil samples by mixing 100 mg of sample with 100 mu L of hexane, 8% (w/v) Triton X-114, and 3.3 mol L-1 HNO3. The accuracy of the proposed method was confirmed through the analysis of two standard reference materials (B100 biodiesel soy-based and Conostan oil analysis standards) and mineral oil and corn biodiesel samples. (AU)

• FAPESP's process: 11/19730-3 - Cloud point extraction (CPE) and dispersive liquid-liquid microextraction (DLLME) applied in the development of analytical methods for metals preconcentration and spectrometric determination
• Grantee: Ivanise Gaubeur
• Support Opportunities: Regular Research Grants