Janca Josef, Ananieva Irina A, Menshikova Anastasija Yu, Evseeva Tatiana G
Pôle Sciences et Technologie, Université de La Rochelle, Avenue Michel Crépeau, 17042 La Rochelle Cedex 01, France.
J Chromatogr B Analyt Technol Biomed Life Sci. 2004 Feb 5;800(1-2):33-40. doi: 10.1016/j.jchromb.2003.10.014.
Focusing mechanism was effectively exploited to separate large (micrometer-size) particles by using new micro-thermal field-flow fractionation (micro-TFFF). It has been shown that the retention order of micrometer-size particles at high field strength can be explained by the mechanism of steric exclusion only at lowest flow rates of the carrier liquid. A simplistic, purely mechanical model of steric exclusion is not accurate to describe the retention at higher flow rates where the focusing phenomenon appears. Despite the fact that the thickness of the channel for micro-FFF cannot be reduced without taking into account a possible deterioration of the separation due to the contribution of "steric exclusion" mechanism, this paper demonstrates, in agreement with our previous results, that if the operational conditions were conveniently chosen, namely a low flow rate, a reasonable fit of the experimental retention data with the theory of steric exclusion mechanism in FFF was found and the separation of micron-size particles can be accomplished. However, high selectivity and resolution and high-speed separation were achieved if the focusing effect has clearly dominated the FFF mechanism. As a result, it seems that the micro-TFFF is the most universal technique which can be applied for the separation of the synthetic and natural macromolecules within an extended range of molar masses up to ultra-high molar masses and for the particles of various chemical nature and origin in a nano-size range as well as for large (micrometers) particles. Until nowadays, only sedimentation and flow field-flow fractionation techniques in so called "steric" modes were applied for the separations of large size particles. This application of micro-TFFF in focusing mode for the separation of large size particles is the first one described in the literature.
通过使用新型微热场流分级法（micro-TFFF），聚焦机制被有效地用于分离大尺寸（微米级）颗粒。研究表明，仅在载液流速最低时，微米级颗粒在高场强下的保留顺序才能用空间排阻机制来解释。一个简单的、纯粹机械的空间排阻模型并不准确，无法描述在出现聚焦现象的较高流速下的保留情况。尽管如果不考虑“空间排阻”机制的贡献可能导致分离效果变差，微流场流分级法（micro-FFF）通道的厚度就无法减小，但本文与我们之前的结果一致表明，如果方便地选择操作条件，即低流速，实验保留数据就能与场流分级法（FFF）中的空间排阻机制理论有合理的拟合，并且可以实现微米级颗粒的分离。然而，如果聚焦效应明显主导了FFF机制，就能实现高选择性、高分辨率和高速分离。结果表明，微热场流分级法（micro-TFFF）似乎是最通用的技术，可用于分离摩尔质量范围从低到超高摩尔质量的合成和天然大分子，以及纳米尺寸范围内各种化学性质和来源的颗粒，还有大尺寸（微米级）颗粒。到目前为止，只有沉降法和所谓“空间”模式的流场流分级技术被用于分离大尺寸颗粒。微热场流分级法（micro-TFFF）在聚焦模式下用于分离大尺寸颗粒的这种应用是文献中首次描述的。
