ICOA (Institut de Chimie Organique et Analytique), Université d'Orléans, CNRS UMR 7311, B.P. 6759, rue de Chartres, 45067 Orléans cedex 2, France.
J Chromatogr A. 2012 Aug 10;1250:220-6. doi: 10.1016/j.chroma.2012.04.065. Epub 2012 May 3.
Due to the renewal of the use of supercritical fluid chromatography (SFC), the coupling of SFC with evaporative light scattering detection (ELSD) needs to be revisited. Indeed, SFC and ELSD apparatus have evolved, while understanding of the nebulisation process has improved. This detector, first developed for polymer analyses can be used for a lot of compounds that do not display sufficient UV absorption. Because the response of ELSD is related to numerous parameters, such as mobile phase composition, the velocity difference between the mobile phase and the nebulisation gas, or the nebulisation temperature, many additional studies are necessary to understand its behaviour in SFC as compared to HPLC. The effects of the nature of co-solvent added to carbon dioxide (methanol, ethanol and acetonitrile), the injected volume and the flow rate on the ELSD response were studied. Certain parameters induce great changes on the nebulisation recovery (the proportion of mobile phase entering the drift tube), allowing for a dramatic improvement in peak area. Moreover, effects of the particle size in the aerosol were also observed, related, as expected, to the modifier nature, but strangely also to the injected volume. Specific and positive behaviour of the ELSD detection on the apparent peak efficiency was confirmed in SFC, for large injected volumes. Finally, a flow rate increase reduces peak area, showing that the use of high flow rates, although attractive to shorten analysis duration, is not favourable to ELSD response. Numerous parameters acting on detector response are modified by the flow rate change, such as the mobile phase velocity. Moreover, measurement of the nebulisation chamber temperature shows the strong decrease of temperature for high flow rates, due to the supercritical fluid depressurisation.
由于超临界流体色谱 (SFC) 的重新使用，需要重新考察 SFC 与蒸发光散射检测 (ELSD) 的联用。实际上，SFC 和 ELSD 仪器已经发展，同时对雾化过程的理解也有所提高。这种最初为聚合物分析开发的检测器可用于许多不具有足够紫外吸收的化合物。由于 ELSD 的响应与许多参数有关，例如流动相组成、流动相和雾化气体之间的速度差或雾化温度，因此需要进行许多额外的研究，以了解其在 SFC 中的行为与 HPLC 的区别。研究了向二氧化碳中添加共溶剂（甲醇、乙醇和乙腈）的性质、注入体积和流速对 ELSD 响应的影响。某些参数会对雾化回收率（进入漂移管的流动相比例）产生很大影响，从而显著提高峰面积。此外，还观察到气溶胶中颗粒大小的影响，这与预期的改性剂性质有关，但奇怪的是也与注入体积有关。在 SFC 中，对于大的注入体积，ELSD 检测对表观峰效率具有特异性和阳性行为得到了确认。最后，流速增加会降低峰面积，表明虽然使用高流速可以缩短分析时间，但对 ELSD 响应不利。许多作用于检测器响应的参数会因流速变化而改变，例如流动相速度。此外，测量雾化室温度表明，由于超临界流体减压，流速增加会导致温度急剧下降。
