Shalliker R Andrew, Guiochon Georges
Nanoscale Organisation and Dynamics Group, University of Western Sydney, Parramatta, NSW, Australia.
J Chromatogr A. 2009 Jan 30;1216(5):787-93. doi: 10.1016/j.chroma.2008.11.067. Epub 2008 Nov 30.
The effect of solvent viscosity mismatch on elution performance in reversed-phase HPLC was studied using moment analysis. Two conditions were tested: (1) the mobile phase viscosity was less than the injection plug viscosity, and (2) the mobile phase viscosity was greater than the injection plug viscosity. Under the first condition, retention time and elution performance decreased as the viscosity contrast between the mobile phase and injection plug increased. The effect on performance was more marked as the injection volume increased. A decrease in performance of 12% for compounds with retention factors up to 2.8 was apparent even when the viscosity contrast was only 0.165 cP. In the second set of conditions, elution performance was actually observed to increase, by as much as 25% for a 40 microL injection, as the viscosity contrast between the mobile phase and the solute plug increased. No change in the retention factor was observed. This behaviour was attributed to the shape of an injection plug as it enters into the column, whereby a low viscosity plug permeates away from the wall when the column contains a higher viscosity mobile phase, and vice a versa for a high viscosity plug entering a low viscosity mobile phase. At no stage was either a band splitting or shoulders observed with viscosity contrasts up to 1.283 cP, as could have been expected.
采用矩量分析研究了溶剂粘度失配对反相高效液相色谱洗脱性能的影响。测试了两种条件：（1）流动相粘度小于进样塞粘度，（2）流动相粘度大于进样塞粘度。在第一种条件下，随着流动相和进样塞之间的粘度差异增大，保留时间和洗脱性能下降。进样体积增加时，对性能的影响更为明显。即使粘度差异仅为0.165 cP，保留因子高达2.8的化合物的性能也明显下降了12%。在第二组条件下，随着流动相和溶质塞之间的粘度差异增大，实际观察到洗脱性能增加，对于40 μL进样，增加幅度高达25%。未观察到保留因子的变化。这种行为归因于进样塞进入色谱柱时的形状，当色谱柱含有较高粘度的流动相时，低粘度塞会从壁面渗透出去，而高粘度塞进入低粘度流动相时则反之。在粘度差异高达1.283 cP的任何阶段，均未观察到预期的谱带分裂或肩峰现象。
