FAAS Determination of Sodium in Edible Oil

Samples of edible oil were dissolved with n-hexane and extracted with HNO3 (1+99) solution. After centrifugation, the content of Na+ ion in aqueous phase was determined by FAAS. Linear relationship between values of absorbance and mass concentration of Na+ ion was kept in the range of 0.2-4.0 mg·L-1, with detection limit (3s) of 0.004 7 mg·L-1. Recovery and precision of the method were tested by analyzing an olive oil sample with addition of sodium standard solution, giving values of recovery and RSD′s (n=6) in ranges of 72.4%-89.2% and 1.3%-2.8% respectively.