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Feasibility of Dispersive Liquid-Liquid Microextraction to Determine Ca, Mg, K, and Na in Biodiesel by Atomic Spectrometry

Abstract

This work describes the development of a dispersive liquid-liquid microextraction (DLLME) sample preparation procedure for the determination of Ca, Mg, Na, and K in renewable biodiesel sample by atomic spectrometry. The proposed DLLME was based on the extraction of the analyte from the biodiesel into a micro-drop of acid:alcohol extractive aqueous phase at the conical bottom of the tube. Among the parameters that influence the extraction procedure, sample mass, extractive solution volume, acidic concentration and composition of the extractive solution were evaluated to achieved satisfactory extractions. Using a 20 mg kg-1 Ca-Mg-Na-K-P metallo-organic standard biodiesel B100, the optimized extraction conditions of DLLME were established using 24 full factorial design and Doehlert matrix multivariate analysis. Best results were obtained with 3.0 g sample mass and 780 µL of 5.0% (v/v) HNO3:isopropyl alcohol [3:1 (v/v)] extractive solution. The accuracy of the sample preparation procedure was evaluated by recovery test, and the recoveries percentages were within 90.2-94.7% interval with relative standard deviation (RSD) < 2.0%. The precision of the method was evaluated by analysis of 10 independent and multielementar standard solutions, and the values were less than 2.0%-Ca, 2.5%-Mg, 1.7%-Na, and 1.3%-K. The limits of detection (LOD) were 32.3, 4.3, 3.0, and 5.8 µg kg-1 for Ca, Mg, Na, and K, respectively. Therefore, the developed procedure was successfully applied for Brassica napus L., Crambe Hochst abyssinica, Helianthus annuus and Jatropha curcas biodiesel samples, and the results were in the ranges of 0.92±0.07 – 1.46±0.04 mg kg-1 (Ca), 0.42±0.02 – 9.60±0.29 mg kg-1 (Na), 0.11±0.01 – 2.69±0.05 mg kg-1 (K), and 17.84±0.76 – 57.63±0.95 (Mg) µg kg-1. The DLLME can be used as an alternative and non-destructive sample preparation procedure for biodiesel samples.

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Publication details

The article was received on 06 Apr 2018, accepted on 05 Jun 2018 and first published on 05 Jun 2018


Article type: Technical Note
DOI: 10.1039/C8AY00770E
Citation: Anal. Methods, 2018, Accepted Manuscript
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    Feasibility of Dispersive Liquid-Liquid Microextraction to Determine Ca, Mg, K, and Na in Biodiesel by Atomic Spectrometry

    K. R. N. da Silva, A. S. Greco, M. Z. Corazza and J. L. Raposo, Anal. Methods, 2018, Accepted Manuscript , DOI: 10.1039/C8AY00770E

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