石墨炉原子吸收法中As、Sb、Se、Te的原子化机理研究

Atomization Mechanism of As, Sb, Se, and Te in Furnace AAS

本文应用热力学和动力学相结合的方法研究了石墨炉原子吸收法中As、sb、se、Te的原子化机理。应用作者早先提出的公式 k=kd×(At/(A-At))计算温度下的原子形成常数k,绘制Arrhenius图。通过直线斜率得到的原子化活化能来确定各元素的原子化过程。实验表明,As和se是以固态金属进行原子化,而Sb则与介质有关,在盐酸介质中以气相氯化物解离原子化:在硝酸介质中以双原子分子原子化。Te与Sb类似,且与灰化温度有关。

The mechanism of atom formation for As, Sb, Se and Te in graphite furnace atomic absorption Spectrometry was studied through a combined thermodynamic and kinetic approach. The rate of atom formation (K) at a given temperature was calculated by using the corresponding absorbance(At)and the maxinum absobance (Amax) :K = Kd×At/(Amax- At) where Kd is the dissipation constant. An Arrhenius plot obtained should yield a straight line with a slope of - Ea/R. The .vaporization mechanism was clarified by the use of the activation energy Ea, which can be found from the slope of the plot. The experiment showed that the mechanism is different in different cases:through vaporization of metal-As and Se, and Te in HNO3 solution;through thermal dissociation of the halide-Sb and Te in HC1 solution;through dissociation of the dimer-Sb in HNO3 solution.