小型MPT全谱仪用于中药材葛根中微量元素的测定

采用湿法消解处理样品,应用小型MPT全谱仪对中药材葛根中的镁、铜、铁、钙、锶和钡等6种微量元素进行了测定。讨论了实验参数的最佳化,得到了较好的测量结果,各元素回收率在87%～113%之间,测量精密度均小于2%。     

微波等离子体炬原子发射光谱法测定米粉中微量元素——一个大学化学仪器分析实验的设计与实践

设计了一个科研参与型的大学化学仪器分析实验。本实验应用MPT原子发射光谱仪对米粉中的金属元素(Ca,Cu,Fe,Mn)进行了检测分析。对影响金属元素检测性能的实验条件,如微波等离子体炬的微波功率和维持气流量进行了系统的考查及优化。最后,通过对样品进行测定,证实与标准含量相符,结果比较满意。学生在实验过程中,可以学习和掌握样品的前处理方法、原子发射光谱的机理和仪器测试条件的优化。     

鬼臼毒素及其衍生物热分解反应的动力学研究

The thermal behavior and thermal decomposition kinetic parameters of podophyllotoxin （1） and 4 derivatives, picropodophyllin （2）, deoxypodophyllotoxin （3）, fl-apopicropodophyllin （4）, podophyllotoxone （5） in a temperature-programmed mode have been investigated by means of DSC and TG-DTG. The kinetic model functions in differential and integral forms of the thermal decomposition reactions mentioned above for first stage were established. The kinetic parameters of the apparent activation energy Ea and per-exponential factor A were obtained from analy- sis of the TG-DTG curves by integral and differential methods. The most probable kinetic model function of the decomposition reaction in differential form was （1- a）^2 for compounds 1-3,2/3·a^-1/2 for compound 4 and 1/2（1-a）·[-In（1-a）]^-1 for compound 5. The values of Ea indicated that the reactivity of compounds 1-5was increased in the order： 5〈4〈2〈1〈3. The values of the entropy of activation △S^≠, enthalpy of activation △H^≠ and free energy of activation △G^≠ of the reactions were estimated. The values of △G^≠ indicated that the thermal stability of compounds 1-3 with the samef（a） was increased in the order： 2〈3〈1.