We investigate an explicit role of the ionic strength in the retention behaviors of polystyrene (PS) latex particles in sedimentation field-flow fractionation (SdFFF) by hinging upon the retention theory recently developed [1] as$R=\left(R_o+v_b^{*}\right)/\left(1+v_b^{*}\right)$. Here R is an experimental retention ratio, and R_o is the analytical expression of the standard retention theory based on the parabolic flow velocity. The reduced boundary velocity$v_b^{*}$ is expressed in terms of the ionic strength I of the carrier liquid as $v_b^{*}=v_{b,o}^{*}/\left(1+\sqrt{\epsilon I}\right)$, where $v_{b,o}^{*}=0.070$and ε = 60 mM⁻¹ for all the PS latex systems under investigation. We then apply this to study the explicit ionic strength effect on the retention behaviors of PS beads of 200, 300, 400, and 500 nm, respectively. As a primary result, the strong dependence of the retention ratio on the ionic strength can be quantitatively accounted for in an excellent accuracy: The slip effect at the channel surface is significant, particularly when I ≲ 0.5 mM, without showing any distinguishable dependence on the specific additives to control I, such as FL-70, SDS, NaNO₃, and NaN₃. Based on the present study, we put forward an experimental means to estimate the ionic strength of an aqueous solution using an FFF technique.

我们根据最近发展的保留理论[1]，研究了离子强度在聚苯乙烯（PS）胶乳颗粒在沉降场流分馏（SdFFF）中的保留行为中的明确作用。$\mathrm{[R}=（{\mathrm{[R}}_{Ø}+v_b^{*}）/（\mathrm{1个}+v_b^{*}）$。在此，R是实验保留率，R _o是基于抛物线流速的标准保留理论的解析表达式。降低的边界速度$v_b^{*}$用载液的离子强度I表示为$v_b^{*}=v_{b，Ø}^{*}/（\mathrm{1个}+\sqrt{\epsilon \mathrm{一世}}）$， 在哪里 $v_{b，Ø}^{*}=0.070$对于所有正在研究的PS胶乳系统，ε  = 60 mM ^-1。然后，我们将其应用到研究显着的离子强度对分别为200、300、400和500 nm的PS珠的保留行为的影响。作为一个主要的结果，强的离子强度保持率的依赖性，可以定量在一个优越的精度占：在流道表面的防滑效果是显著，特别是当我 ≲0.5毫米，没有示出对任何可区分的依赖控制I的特定添加剂，例如FL-70，SDS，NaNO ₃和NaN ₃。基于目前的研究，我们提出了一种使用FFF技术估算水溶液离子强度的实验方法。