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

摘要

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 0.10g of samples [0.5% (m/v)]+200L HNO3 [1.0% (v/v)]+200L Triton X-100 [1.0% (v/v)] in 16mL of anhydrous ethanol [80% (v/v)] and 3.50mL of aqueous phase [17.5% (v/v)], whereas the microemulsions were obtained with 0.10g of samples [0.5% (m/v)]+200L HNO3 [1.0% (v/v)]+200L Triton X-100 [1.0% (v/v)] in 18mL of 1-butanol [90% (v/v)] and 1.50mL 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 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 0.1gg(-1) (IS-Co) and 0.2gg(-1) (IS-Cu). The content of Mg in four crude vegetable oil varied in the range of 8.91 +/- 0.30 to 163.88 +/- 0.48gg(-1) for both dispersion systems with RSD 4.22%.