Internal Standardization in Dispersion Systems: an Efficient Application to Determine Mg in Crude Vegetable Oils by FS-F
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Internal Standardization in Dispersion Systems: an Efficient Application to Determine Mg in Crude Vegetable Oils by FS-FAAS Liriana Mara Roveda 1 & Jorge Luiz Raposo Jr 1,2 Received: 17 October 2018 / Accepted: 14 January 2019 # Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract This study established two sample preparation procedures based on dispersion systems for the determination of Mg in crude vegetable oil by IS-FS-FAAS. The emulsions were obtained with 0.10 g of samples [0.5% (m/v)] + 200 μL HNO3 [1.0% (v/v)] + 200 μL Triton X-100 [1.0% (v/v)] in 16 mL of anhydrous ethanol [80% (v/v)] and 3.50 mL of aqueous phase [17.5% (v/v)], whereas the microemulsions were obtained with 0.10 g of samples [0.5% (m/v)] + 200 μL HNO3 [1.0% (v/v)] + 200 μL Triton X100 [1.0% (v/v)] in 18 mL of 1-butanol [90% (v/v)] and 1.50 mL of aqueous phase [7.5% (v/v)]. To overcome non-spectral interference, Cd, Co, and Cu were used as internal standards, and the slopes of calibration curves for Mg in 1.0% (v/v) HNO3 aqueous solution, anhydrous ethanol + 1.0% (v/v) Triton X-100, and 1-butanol + 1.0% (v/v) Triton X-100 showed no significant difference at the 95% confidence level using Co and Cu. Calibration curves were obtained by plotting AMg/ACo and AMg/ACu vs Mg concentration with linear correlation coefficients better than 0.9972 and 0.9986, respectively. The accuracy was evaluated using recovery tests, and recoveries of 98.4–106.6% (IS-Co) and 93.9–106.9% (IS-Cu) were obtained. The RSD (n = 5) were 0.4–3.6% (IS-Co) and 0.3–3.6% (IS-Cu), and LOD were 0.1 μg g−1 (IS-Co) and 0.2 μg g−1 (IS-Cu). The content of Mg in four crude vegetable oil varied in the range of 8.91 ± 0.30 to 163.88 ± 0.48 μg g−1 for both dispersion systems with RSD < 4.22%. Keywords Magnesium . Alternative oilseed crop . Internal standardization . Emulsion . Microemulsion
Introduction Vegetable oils and dietary fats, which are widely consumed in the human diet, are considered the most concentrated sources of energy in foods (Llorent-Martínez et al. 2011; LópezGarcía et al. 2014). Near to 80% of vegetable oils produced are used for feed (Gunstone 2002), and others are employed to manufacture cosmetics, pharmaceuticals, and insecticides (Dugo et al. 2004; Trindade et al. 2015). Approximately 4000 vegetable species can be used to obtain crude vegetable oils (Santori et al. 2012), with the most common species in Brazil including palm, soybean, corn, cottonseed, sunflower, canola, peanut, olive, and coconut. However, owing to the recent search for new energy sources (Amais et al. 2010; Lyra et al. 2010; Pereira et al. 2013), greater attention is being
* Jorge Luiz Raposo, Jr [email protected] 1
Faculty of Exact Science and Technology, Federal University of Grande Dourados, PO Box 364, Dourados, MS 79804-970, Brazil
2
Institute of Chemistry, Federal University of Mato Grosso do Sul, PO Box 549, Campo Grande, MS 79070-900, Brazil
given to obtaining and ensuring the quality of raw materials from alternative oilseed species to enlarge the
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