On-Column Temperature Programming in Gas Chromatography Using Temperature Gradients along the Capillary Column
On-Column Temperature Programming in Gas Chromatography Using Temperature Gradients along the Capillary Column
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使用沿毛细管柱的温度梯度进行气相色谱中的柱上温度编程
DOI：
10.1093/chromsci/33.10.541
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发表时间：
1995
影响因子：
1.3
通讯作者：
V. Jain
中科院分区：
文献类型：
--
作者：
J. Phillips;V. Jain
描述了一种独特的高速气相色谱柱上程序升温技术。通过在柱外部施加薄导电膜对柱进行直接电阻加热，可以将时间和距离上的同时温度梯度施加到熔融石英毛细管柱。受控电流斜坡提供与常规温度编程类似的时间上的热梯度。电阻梯度提供了沿着柱的温度梯度，并且柱的头部总是处于比柱的末端更高的温度。梯度沿着色谱柱连续地重新聚焦洗脱带，抵消部分色谱带的扩展。带的后部温度高于前部，因此以略高的速度移动。通过适当限定的温度梯度表面，每种物质达到由时间和距离梯度的比率以及载气速度确定的聚焦容量因子。该聚焦容量因子的数值与所涉及的物质无关，但其在时间和沿着色谱柱的距离上的轨迹取决于单个物质与固定相相互作用的热力学。文中还阐述了沿柱体沿着方向的时间和距离上同时存在温度梯度的理论，并给出了聚焦容量因子和分辨率的数学表达式。几个例子，包括色谱图，往往每2秒，显示支持和补充的理论。
A unique technique for high-speed gas chromatography using on-column temperature programming is described. Simultaneous temperature gradients in time and distance can be applied to a fused-silica capillary column by direct resistive heating of the column through a thin electrical conductive film applied to the outside of the column. A controlled current ramp provides a thermal gradient in time analogous to conventional temperature programming. An electrical resistance gradient provides a temperature gradient along the column, and the head of the column is always at a higher temperature than the end of the column. The gradient along the column continuously refocuses eluting bands, counteracting part of the chromatographic band spreading. The rear of the band is at a higher temperature than the front and, thus, moves at a slightly higher velocity. With a properly defined temperature gradient surface, each substance reaches a focus capacity factor that is determined by the ratio of gradients in time and distance and by carrier gas velocity. The numerical value of this focus capacity factor is independent of the substance involved, but its trajectory in time and distance along the column depends on the thermodynamics of an individual substance's interaction with the stationary phase. The theory of simultaneous temperature gradients in time and distance along the column is also described, and the mathematical expressions for focus capacity factor and resolution are included. Several examples, including chromatograms as often as one every 2 s, are shown to support and complement the theory.