TU Dortmund, Faculty of Chemistry, Otto-Hahn-Strasse 6, 44227 Dortmund, Germany.
J Chromatogr A. 2012 Jun 1;1240:77-82. doi: 10.1016/j.chroma.2012.03.077. Epub 2012 Apr 1.
A new approach for on-line SEC-NMR is introduced. The method combines time slicing, fractionation with adjusted loop collection and automatic stop-flow NMR analysis. It will be called on-line fractionated SEC-NMR. This technique allows the precise determination of molar mass distributions for any polymer which can be detected by NMR. It is a significant improvement of sensitivity and accuracy compared to onflow SEC-NMR and exhibits a much easier experimental setup than off-line SEC-NMR fractionation. The new method was applied to protonated and deuterated block copolymers by using ¹H NMR and for the first time also ²H NMR detection. In this case block copolymers can be correctly characterized according to their block length distributions. As the consequence very precise molar mass parameters M(n) and M(w) can be determined. The results of the on-line fractionated SEC-NMR are in very good agreement with the multi detector analysis. The new technique also proposes a method for separating the true copolymer and low molar mass fractions in the mixture, whose structures are confirmed by HPLC-FTIR and 2D chromatography.
介绍了一种在线 SEC-NMR 的新方法。该方法结合了时间切片、分段与调整的环收集和自动停流 NMR 分析。它将被称为在线分段 SEC-NMR。与在线流 SEC-NMR 相比，该技术可用于通过 NMR 检测的任何聚合物的精确摩尔质量分布的确定，其灵敏度和准确性有显著提高，且与离线 SEC-NMR 分段相比，其实验设置更加简单。该新方法应用于质子化和氘代嵌段共聚物，采用 ¹H NMR 并首次采用 ²H NMR 检测。在这种情况下，嵌段共聚物可以根据其嵌段长度分布正确表征。结果表明，非常精确的摩尔质量参数 M(n)和 M(w)可以被确定。在线分段 SEC-NMR 的结果与多检测器分析非常吻合。该新技术还提出了一种从混合物中分离真正的共聚物和低摩尔质量分数的方法，其结构通过 HPLC-FTIR 和二维色谱法得到证实。
