HG-AFS Determination of Selenium in Water with Field-Enanced Stacking

HG-AFS was applied to the determination of selenium in water with field-enanced stacking. A field-enhanced stacking equipment was developed. Under application of electric field, selenium anion was migrated from water sample solution to enrichment solution of higher conductivity and concentrated. The optimized conditions found were as follows: ① electrode distance was 4 cm; ② volume of enrichment cavity was 3.0 mL; ③ enrichment solution was PBS; ④ field current was 80 mA; ⑤ enrichment time was 8 min. Linear relationship between values of fluorescence intensity and mass concentration of selenium was kept in the range of 3.0-200 ng·L^-1, with detection limit (3σ) of 1.8 ng·L^-1. Tests for recovery were made by standard addition method at the concentration level of 20 ng·L^-1, giving values of recovery in the range of 98.0%-106%. The proposed method was applied to the analysis of national standard sample GSBZ 50031-94, giving result in consistency with the certified value with RSD (n=5) of 1.2%.