Martin M, Van Batten C, Hoyos M
Ecole Supérieure de Physique et Chimie Industrielles, Laboratoire de Physique et Mécanique des Milieux Hétérogènes (URA CNRS 857), 10, rue Vauquelin, 75231 Paris Cedex 05, France.
Anal Chem. 1997 Apr 1;69(7):1339-46. doi: 10.1021/ac9605307.
In some field-flow fractionation (FFF) techniques, the basic analyte-field interaction parameter, λ, is not constant but varies within the channel cross section as a result of the nonuniformity of the force exerted by the field on the analyte. This is the case, for instance, in thermal FFF, because of the temperature dependence of the relevant physicochemical transport parameters. To account for this effect, a new FFF retention model is developed, allowing a linear variation of λ from the accumulation to the depletion wall, which is assumed to describe correctly moderate nonuniformity in λ in the vicinity of the accumulation wall. A methodology for sample characterization on the basis of this model is proposed. It associates λ(app), the apparent λ value derived from the retention ratio by means of the classical retention model, with a specific distance from the accumulation wall. An empirical relationship between that distance and λ(app) is derived. In the high retention limit, it is found that this specific distance is not equal, as sometimes intuitively believed, to the mean distance of the molecule or particle cloud to the accumulation wall but is approximately equal to twice this mean distance. The validity of the proposed approach is checked.
在某些场流分级（FFF）技术中，基本分析物 - 场相互作用参数λ并非恒定不变，而是由于场对分析物施加的力的不均匀性，在通道横截面上会发生变化。例如，在热场流分级中就是这种情况，这是由于相关物理化学传输参数对温度的依赖性所致。为了考虑这种效应，开发了一种新的场流分级保留模型，该模型允许λ从富集壁到耗尽壁呈线性变化，假定这种变化能够正确描述富集壁附近λ的适度不均匀性。在此基础上提出了一种基于该模型的样品表征方法。该方法将通过经典保留模型从保留比得出的表观λ值λ(app)与距富集壁的特定距离相关联。推导出了该距离与λ(app)之间的经验关系。发现在高保留极限情况下，这个特定距离并不像有时直观认为的那样等于分子或颗粒云到富集壁的平均距离，而是大约等于该平均距离的两倍。对所提出方法的有效性进行了检验。
