Aerosol-Phase Extraction Method for Determination of Ca, K, Mg, and Na in Biodiesel through Inductively Coupled Plasma Optical Emission Spectrometry

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Title: Aerosol-Phase Extraction Method for Determination of Ca, K, Mg, and Na in Biodiesel through Inductively Coupled Plasma Optical Emission Spectrometry
Authors: Sánchez, Raquel | Maestre, Salvador E. | Prats Moya, Soledad | Todolí Torró, José Luis
Research Group/s: Análisis de Polímeros y Nanomateriales | Análisis de Alimentos y Nutrición
Center, Department or Service: Universidad de Alicante. Departamento de Química Analítica, Nutrición y Bromatología
Keywords: ICP-OES | Liquid – liquid Extraction | Aerosol phase extraction | Metals | Biodiesel
Knowledge Area: Química Analítica | Nutrición y Bromatología
Issue Date: 15-Nov-2017
Publisher: American Chemical Society
Citation: Analytical Chemistry. 2017, 89(24): 13618-13625. doi:10.1021/acs.analchem.7b04205
Abstract: A novel extraction method was developed, optimized, and validated for the elemental analysis of organic samples. The method, called aerosol-phase extraction (APE), is based on nebulization of the extracting aqueous solution (0.1 mol·L–1 nitric acid) on the sample. Extraction was performed at the interface of generated extractant droplets as they entered into contact with the samples. Afterward, the phases were allowed to separate and Ca, K, Na, and Mg were determined in aqueous phase by means of inductively coupled plasma optical emission spectroscopy (ICP-OES). Measurement of aerosol characteristics demonstrated that a water-in-oil emulsion was generated. Therefore, once the aqueous solution was dispersed into the sample, the phases spontaneously separated. Furthermore, the interfacial specific surface area exhibited values on the order of 1 m2·mL–1, hence enhancing the extraction kinetics over conventional extraction methods. Key variables affecting the extraction yield were the nebulization gas flow rate, liquid flow rate, extraction time, acid concentration, nebulizer tip to sample surface gap, and morg/maq ratio. Once the optimal conditions were selected, the method was applied and validated for the determination of Ca, K, Na, and Mg by ICP-OES in 0.5 mL biodiesel samples with an expanded uncertainty lower than 2%. With the APE method, the extraction time was around 1 min, whereas conventional methods employed to perform this kind of extraction required from 4 to 50 min. Additionally, the APE involved preconcentration of analytes, thus lowering the limit of detection (LOD) to the nanograms per milliliter level (i.e., LODs based on the 3sb criterion were 32, 20, 19, and 24 ng·mL–1 for Ca, K, Na, and Mg, respectively). Furthermore, accuracy of quantification of Ca, K, Na, and Mg concentration by APE was not significantly different as compared to that afforded by conventional liquid–liquid extraction. Finally, Ca, K, Na, and Mg contents were determined in four real samples in the 0.5–13 mg·kg–1 range. The obtained results were not statistically different from those encountered with a microwave-based digestion method.
ISSN: 0003-2700 (Print) | 1520-6882 (Online)
DOI: 10.1021/acs.analchem.7b04205
Language: eng
Type: info:eu-repo/semantics/article
Rights: © 2017 American Chemical Society
Peer Review: si
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Appears in Collections:INV - AAQCN - Artículos de Revistas
INV - NANOBIOPOL - Artículos de Revistas

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