【作者】 郝健；

【导师】 范国樑；

【作者基本信息】 天津大学 ， 材料学， 2009， 硕士

【摘要】 在程序升温气相色谱法中,为达到最佳分离效果,往往需要进行多次重复性预实验。如果能通过计算预测样品组分在任意程序升温条件下的保留时间,就可以避免仅凭经验改变柱温的盲目性,减少预实验次数,从而较快地筛选出最佳升温程序,实现色谱条件的优化。本文以色谱保留值方程为基础,利用非线性塔板理论,对恒压操作模式下的程序升温气相色谱保留时间进行预测。详细介绍保留值方程的建立,重点分析样品组分在恒压操作模式下的保留行为特点并以此为基础设计保留时间的计算程序,探讨用塔板理论预测气相色谱在恒压模式下的程序升温保留时间的可行性。采用一组恒温预实验测定色谱保留值方程。恒温保留时间随温度下降先减小后增加,在某一温度下出现极小值,与恒流模式下单调增加的情况不同,表明必须采用每一恒温温度点下测定的死时间计算组分的容量因子k’。用保留值方程ln k ’ = aT 3 + bT 2+ cT + d,对恒压模式下具有不同官能团的几类有机物样品在弱极性HP-5柱和极性FFAP柱上容量因子k’和温度的关系进行拟合,求取了4个方程系数,获得了各样品的保留值方程。部分样品的lnk’-T拟合曲线也出现极小值或不为保留值方程所限定的单调形式,说明不能直接采用恒流模式下的计算方法预测恒压模式下的保留时间。以非线性塔板理论为基础设计了恒压模式下的计算程序并用于预测保留时间。通过对六种单阶和多阶程序升温条件下,不同类型的样品在HP-5柱和FFAP柱上保留时间的预测准确度进行考察,发现绝大多数预测值与实测值的相对误差在±3%以内,预测较为准确且与样品和色谱柱类型无关,表明非线性塔板理论不仅适用于恒流操作模式,也可用于恒压模式下程序升温保留时间的预测。相对误差的统计结果表明升温速率对预测准确度有明显影响。对几种多阶程序升温条件下6组分混合样品在HP-5柱上的保留时间进行了预测,发现绝大部分样品的相对误差在±3%以内,表明非线性塔板理论不仅适用于单组分样品,也可用于多组分样品在恒压模式下程序升温保留时间的预测。更多还原

【Abstract】 In this paper, retention times in Temperature Programmed Gas Chromatography(TPGC) under constant pressure mode were predicted by retention equations based on the non-linear plate theory. Differences of retention behaviors between constant flow and constant pressure mode were investigated and establishment of retention equations was thoroughly described. A modified calculation method was used to predict retention times in TPGC under constant pressure mode.Retention equations were established through isothermal experiments. For retention times obtained under isothermal temperatures, a minimum time appeared as the column temperature decreased when the gas chromatography was operated under constant pressure mode, which is different to the variation of retention times under constant flow. The relation between capacity factor k’and temperature T of several organic samples with different functional groups on an apolar column HP-5 and a polar column FFAP was fitted by the retention equation ln k ’ = aT 3 + bT 2+ cT + d, thus four coefficients to be determined were obtained.Retention times of samples both in single- and multi-step TPGC were predicted. The calculation method used under constant flow was modified to apply under constant pressure. Relative differences between predicted and measured times were typically in±3% and independent of the nature of sample or column used. The results showed that the non-linear plate theory can be applied not only under constant flow mode, but also constant pressure to predict retention time in TPGC.Retention times of six components in a mixture on column HP-5 were also predicted and most of the relative differences between a predicted and measured times were in±3%. This indicated that non-linear plate theory can also be applied to multi-component samples in predicting retention times of TPGC under constant pressure mode.更多还原