Reduced sample recovery in liquid chromatography at critical adsorption point of high molar mass polystyrene
Reduced sample recovery in liquid chromatography at critical adsorption point of high molar mass polystyrene
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DOI：
10.1016/j.eurpolymj.2007.11.015
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发表时间：
2008-02-01
影响因子：
6
通讯作者：
Bertin, D.
中科院分区：
文献类型：
--
作者：
Beaudoin, E.;Favier, A.;Bertin, D.
如果临界洗脱液没有仔细地安装到系统中，那么样品回收率低可能是临界吸附点液相色谱(LC-CAP)的一个重要缺陷。到目前为止，这个问题经常被忽视，在文献中只能找到很少的实验例子。结果表明，在四氢呋喃(THF)/正己烷临界混合淋洗液中，摩尔质量大于100 kg mol(-1)的聚苯乙烯(PS)不能从孔径分别为30 nm和100 nm的裸硅胶填充柱中洗脱出来。用2D层析法证明，在注入少量纯THF后，柱内捕获的聚合物被很好地回收。我们用小角中子散射的方法研究了PS的构象，发现THF/正己烷临界洗脱液实际上是PS的theta溶剂。通过将其替换为CH2Cl2/正己烷临界混合物，这是PS的良好溶剂，降低了样品回收率的限制，使其转移到更高的摩尔质量。因此，洗脱液的热力学性质或良好的溶剂对样品回收现象起着重要的作用。(C)2007爱思唯尔有限公司。保留所有权利。
Low sample recovery may represent an important drawback in liquid chromatography at the critical adsorption point (LC-CAP) if the critical eluent is not carefully fitted to the system. So far, this problem was often overlooked and only few experimental examples can be found in literature. We showed that in the case of polystyrene (PS) in a tetrahydrofuran (THF)/n-hexane critical mixed eluent, PS with molar masses higher than 100 kg mol(-1) were not eluted from a tandem of two columns packed by bare silica gels with 30 nm and 100 nm pore size, respectively. The polymer trapped within the columns was well recovered after injection of a small volume of pure THF as demonstrated using 2D chromatography. We studied PS conformations by means of small angle neutron scattering and found that the THF/n-hexane critical eluent is in fact a theta solvent for PS. By replacing it by a CH2Cl2/n-hexane critical mixture, which is a good solvent for PS, the limits of reduced sample recovery was displaced towards far higher molar masses. Thus, thermodynamic quality of eluent theta or good solvent - plays an important role on the phenomenon of sample recovery. (c) 2007 Elsevier Ltd. All rights reserved.