Internal Standardization in Dispersion Systems: an Efficient Application to Determine Mg in Crude Vegetable Oils by FS-FAAS

• Published in: Food analytical methods 2019-05, Vol.12 (5), p.1111-1120
• Main Authors: Roveda, Liriana Mara, Raposo, Jorge Luiz
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Aqueous solutions; Butanol; Calibration; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Confidence intervals; Correlation coefficients; Crude oil; Dispersion; Edible oils; Emulsions; Ethanol; Food Science; Microbiology; Microemulsions; Oils & fats; Sample preparation; Standardization; Vegetable oils; Vegetables
• ISSN: 1936-9751; 1936-976X
• DOI: 10.1007/s12161-019-01439-1

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 HNO 3 [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 HNO 3 [1.0% ( v / v )] + 200 μL Triton X-100 [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 ) HNO 3 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 A Mg /A Co and A Mg /A Cu 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