Instrumental Idiosyncrasies Affecting the Performance of Ultrafast Chiral and Achiral Sub/Supercritical Fluid Chromatography
Instrumental Idiosyncrasies Affecting the Performance of Ultrafast Chiral and Achiral Sub/Supercritical Fluid Chromatography
复制标题
DOI：
10.1021/acs.analchem.6b01898
复制
发表时间：
2016-09-06
影响因子：
7.4
通讯作者：
Armstrong, Daniel W.
中科院分区：
文献类型：
--
作者：
Barhate, Chandan L.;Wahab, M. Farooq;Armstrong, Daniel W.
人们普遍认为，色谱柱技术领先于现有的色谱仪器。色谱输出可能不能反映柱内峰分布的真实情况。当峰值在几秒钟内洗脱时，仪器优化参数变得更加重要。在这项工作中，超临界/亚临界二氧化碳的低粘度优势与窄粒度分布二氧化硅的高效率相结合。使用短的高效柱和高流速(高达19毫升/分钟)，可实现数秒级的分离。在超高速超临界流体色谱(SFC)领域中，出现了超高速液色谱所没有的意外结果。这些影响的产生是由于流动相的可压缩性质和检测器消除背压调节器噪声的特性。我们展示了50、75、127、254和500微米油管的异常连接油管效应，并显示了死区时间、保留时间、效率和最佳速度与油管直径(通过柱出口压力)的复杂关系。在不同背压调节器(BPR)设置下的傅立叶分析表明，某些仪器具有源自背压调节器的非常特定的噪声频率，并且这些特定频率在特定条件下消失。比较了移动平均、数值模拟低通RC和高斯核三种嵌入式数字滤波器的性能。这项工作还证明，使用一个简单的导数测试，一些仪器使用内插技术，同时采样在“真正的”低频率，以避免拾取高频噪声。从事超快层析的研究人员需要了解在SFC模式下实现超快速手性或非手性分离的仪器细微差别和优化程序。
It is widely accepted that column technology is ahead of existing chromatographic instruments. The chromatographic output may not reflect the true picture of the peak profile inside the column. The instrumental optimization parameters become far more important when peaks elute in a few seconds. In this work, the low viscosity advantage of the supercritical/subcritical CO2 is coupled with the high efficiency of narrow particle size distribution silica. Using short efficient columns and high flow rates (up to 19 mL/min), separations on the order of a few seconds are demonstrated. In the domain of ultrafast supercritical fluid chromatography (SFC), unexpected results are seen which are absent in ultrafast liquid chromatography. These effects arise due to the compressible nature of the mobile phase and detector idiosyncrasies to eliminate back-pressure regulator noise. We demonstrate unusual connection tubing effects with 50, 75, 127, 254, and 500 mu m tubings and show the complex relation of dead time, retention time, efficiency, and optimum velocity with the tubing diameter (via column outlet pressure). Fourier analysis at different back-pressure regulator (BPR) settings shows that some instruments have very specific noise frequencies originating from the BPR, and those specific frequencies vanish under certain conditions. The performance of embedded digital filters, namely, moving average, numerically simulated low pass RC, and Gaussian kernels, is compared. This work also demonstrates, using a simple derivative test, that some instruments employ interpolation techniques while sampling at "true" low frequencies to avoid picking up high frequency noise. Researchers engaged in ultrafast chromatography need to be aware of the instrumental nuances and optimization procedures for achieving ultrafast chiral or achiral separations in SFC mode.