北虫草试样经硝酸-高氯酸(5+1)混合酸消解,用原子荧光光谱法测定总硒的含量;北虫草试样用盐酸浸提,用原子荧光光谱法测定无机硒的含量。使用溶于5 g·L-1氢氧化钾溶液中的20 g·L-1硼氢化钾溶液使与溶液中硒离子反应生成氢化物。分析中采用载气及屏蔽气的流量依次为500 mL·min-1及1 000 mL·min-1。荧光强度与硒的质量浓度在100 μg·L-1以内呈线性关系,方法的检出限(3s/k)为0.2 μg·L-1。应用此法测定北虫草中硒的含量,总砷测定值的相对标准偏差(n=5)在3.4%~3.9%之间,无机硒的平均回收率为103%。

The sample of north cordyceps was digested with mixed acid of HNO3-HClO4 (5+1), and the content of total selenium in sample solution was determined by HG-AFS. The sample was leached with HCl, and the content of inorganic selenium was determined by HG-AFS. Hydride of Se ion was generated by reacting with 20 g·L-1 KBH4 solution (dissolved in 5 g·L-1 KOH solution). Flow-rates of 500 mL·min-1 for carrier gas and 1 000 mL·min-1 for shielding gas were taken in the analysis. Linear relationship between values of fluorescence intensity and mass concentration of Se found was in the range within 100 μg·L-1, with detection limit (3s/k) of 0.2 μg·L-1. The proposed method was applied to the determination of Se in north cordyceps, giving values of RSD′s (n=5) in the range of 3.4%-3.9% for total Se and average recovery of 103% for inorganic Se.