de Villiers André, Lauer Henk, Szucs Roman, Goodall Stuart, Sandra Pat
Pfizer Analytical Research Centre, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium.
J Chromatogr A. 2006 Apr 28;1113(1-2):84-91. doi: 10.1016/j.chroma.2006.01.120. Epub 2006 Feb 14.
The effects of viscous heat dissipation on some important HPLC parameters, such as efficiency (N) and retention factors (k), using 2.1mm columns at pressures up to 1000 bar have been investigated from both a theoretical and experimental point of view. Two distinct experimental set-ups and their respective influences on non-homogenous temperature gradients within the column are described and discussed. In the first instance, a still-air column heater was used. This set-up leads to approximate 'adiabatic' conditions, and a longitudinal temperature gradient is predicted across the length of the column. The magnitude of this gradient is calculated, and its occurrence confirmed with experimental measurements also indicating that no appreciable loss in efficiency occurs. Secondly, when a water bath is used to thermostat the column, a radial temperature gradient is prevalent. The extent of this gradient is estimated, and the loss in efficiency associated with this gradient is predicted and demonstrated experimentally. It is also observed that approximate adiabatic conditions can lead to floating retention factors. The implications of temperature gradients for routine HPLC analysis at ultra-high pressure are discussed.
从理论和实验的角度研究了粘性热耗散对一些重要的高效液相色谱（HPLC）参数的影响，这些参数包括使用内径2.1mm的色谱柱在高达1000巴的压力下的柱效（N）和保留因子（k）。描述并讨论了两种不同的实验装置及其对色谱柱内非均匀温度梯度的各自影响。首先，使用了静止空气柱加热器。这种装置导致近似“绝热”条件，并预测在色谱柱长度上存在纵向温度梯度。计算了该梯度的大小，并且通过实验测量证实了其存在，实验测量还表明柱效没有明显损失。其次，当使用水浴对色谱柱进行恒温时，径向温度梯度较为普遍。估计了该梯度的程度，并预测并通过实验证明了与该梯度相关的柱效损失。还观察到近似绝热条件会导致保留因子波动。讨论了温度梯度对超高压常规HPLC分析的影响。
