A new approach to the determination of column overload characteristics in reversed-phase liquid chromatography
A new approach to the determination of column overload characteristics in reversed-phase liquid chromatography
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DOI：
10.1016/j.chroma.2009.01.036
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发表时间：
2009-03-20
影响因子：
4.1
通讯作者：
McCalley, David V.
中科院分区：
文献类型：
--
作者：
Dai, Jun;Carr, Peter W.;McCalley, David V.
在反相色谱法分离碱性分析物的过程中，色谱柱超载是非常常见的现象。由于离子分析物与固定相和流动相的复杂相互作用，与非极性溶质相比，只有非常少量的电离样品可以被注入，然后通过非线性色谱过程扭曲峰形。通常，在观察到过载之前可以注入的量非常小，以至于信号相当嘈杂，从而使测量的板计数不精确甚至可能不准确。本研究的目的是开发一种实用的方法来精确测量板数和柱过载参数，使用简单但数学上严格的朗穆里亚非线性色谱模型。“过载剖面”，即表观板数与进样量的关系图，由两个参数表征：极限板数（N-0）和柱样负载能力（omega(0.5)）。极限板计数是当进样量很小，以致于线性等温线适用时，应观察到的板计数。柱样品负载能力，即样品负载导致板计数等于限制板计数的一半，是可注入该柱的最大样品量的度量。将该方法应用于RPLC中阳离子分析物的研究。结果表明，在一定条件下（柱长、流量、流动相组成等），No几乎与柱型（制造商）无关；然而，不同的柱类型（在相同的长度、直径和流量下）在样品装载能力（omega(0.5)）上表现出明显的差异。我们认为，对于大多数填料良好的B型柱，柱样品的载荷能力，而不是限制板计数是更重要的性质，说明大多数峰宽的明显差异时，不同类型的柱进行检查。(c) 2009 Elsevier B.V.版权所有
Column overloading is very common during the separations of basic analytes in analytical scale reversed-phase liquid chromatography (RPLC). Due to the complex interactions of ionic analytes with stationary and mobile phases, only a very small amount of ionized sample compared to the amount of nonpolar solute can be injected before the peak shape is distorted by non-linear chromatographic processes. Often the amount that can be injected before overload is observed is so small that the signal is quite noisy, thereby making the measured plate count imprecise and possibly inaccurate. The Purpose of the present study was to develop a practical method for the precise measurement of the plate count and a column overload parameter using a simple but mathematically rigorous model of Langmuirian non-linear chromatography. An "overload profile", i.e. a plot of apparent plate count versus amount injected, is characterized by two parameters: the limiting plate count(N-0)and the column sample loading capacity (omega(0.5)). The limiting plate count is the plate count that should be observed when the amount of sample injected is so small that a linear isotherm pertains. The column sample loading capacity, which is taken as the sample load that leads to a plate count equal to half of the limiting plate count, is a measure of the maximum amount of sample that can be injected into that column. The approach was tested by applying it to the study of cationic analytes in RPLC. We show that No under constant conditions (column length, flow rate, mobile phase composition, etc.) is almost independent of column type (manufacturer); however, different column types (at the same length, diameter and flow rate) exhibit clear differences in their sample loading capacity (omega(0.5)). We believe that for most well packed type B columns, the column sample loading capacity and not the limiting plate count is the more important property that accounts for most of the apparent differences in peak width when different types of columns are examined. (c) 2009 Elsevier B.V. All rights reserved.