HG-AFS Determination of As and Se in Chinese Yam after Enrichment by Coprecipitation

Sample of Chinese yam was digested with HNO3 and H2O2, and the sample solution obtained was adjusted to pH 11-12 and 0.1 mol·L-1 LaCl3 solution was added for coprecipitation with As and Se. The precipitates were separated by centrifugation and dissolved in HCl (1+1) solution, which was used for HG-AFS determination. Under the optimum conditions, linear relationships between fluorescence intensity and mass concentration of As and Se were found in the same range within 40.0 μg·L-1, with detection limits (3σ) of 0.014 μg·L-1 and 0.022 μg·L-1, respectively. The proposed method was applied to the analysis of sample of Chinese yam, values of recovery found were 102% for As and 96.8% for Se.