丹东地区蓝莓中硒的形态分析

探讨了用非完全硝化-交联壳聚糖法,对丹东地区蓝莓中不同形态的痕量硒定量选择性的富集分离条件。结果表明:在pH值为3.0时,交联壳聚糖(CCTS)对Se(Ⅵ)的富集率达97%,而对Se(Ⅳ)几乎无富集;富集Se(Ⅵ)后,用5.0 mL 15 g/L硫脲,2.5 mol/L盐酸溶液可定量洗脱并消除干扰离子;比较了不同的硝化体系,发现HNO3-H2O2-HCl的硝化体系能很好的硝解蓝莓样品,样品中硒的损失小、干扰小,结果稳定;优化了石墨炉原子吸收法测定条件;在最佳条件下,总硒的线性方程为D=1.361 4C+0.408 1,线性范围0.6～157.2μg/L,可决系数r=0.998 3;方法检出限(3σ)为14.2 ng/L;Se(Ⅵ)的线性方程为D=1.193 7C+0.053 9,线性范围0.4～26.1μg/L,可决系数r=0.996 7,检出限(3σ)为16.4 ng/L。回收率为96.6%～107.3%,RSD<5.3%;Se(Ⅳ)、Se(Ⅵ)、有机硒含量范围分别为10.91～11.97、3.48～4.67、101.43～102.33μg/kg。

Preconcentration of Vanadium(Ⅴ) on Crosslinked Chitosan and Determination by Graphite Furnace Atomic Absorption Spectrometry

A new method is proposed for the preconcentration of vanadium(Ⅴ) with crosslinked chitosan (CCTS) and determination by graphite furnace atomic absorption spectrometry (GFAAS). The adsorption rate of vanadium(Ⅴ) by CCTS was 97% at pH 4.0, and vanadium(Ⅴ) was eluted from crosslinked chitosan with 2 mL 2.0 mol·L -1 chlorhydric acid and determined by GFAAS. The detection limit (3σ,n=7) for vanadium(Ⅴ) was 4.8×1 0 -12g and the relative standard deviation (R.S.D) at concentration level of 2.6 μg·L -1 is less than 3.6%. The method shows a good selectivity and high sensitivity, and it was applied to determination of vanadium(Ⅴ) in oyster and water samples. The analytic recoveries are (97±5)%.