The behavior of a novel type of SFC injector, the feed injector, was investigated. In SFC, the sample compounds are usually diluted in a solvent which has a higher elution strength than the mobile phase, which leads to solvent mismatch upon injection and evidently band broadening. The feed injector differs from standard injectors as the sample, contained in the sample needle or loop, is not switched in line with the mobile phase flow, but directly injected/added to the mobile phase flow (F). The subsequent mixing of sample and mobile phase flows inherently results in a dilution of the sample, thus reducing the solvent mismatch. However, for a given injection/feed flow rate F_feed, the total volume in which the sample is contained increases with a factor (F_feed+F)/F_feed. In addition, to ensure that all of the loaded sample is injected on the column, an additional overfeed volume (V_ov) needs to be injected after the sample plug. To better understand the effect of these operating parameters, a wide range of injection conditions was investigated by varying the F_feed/F-ratio, V_ov, overfeed solvent etc. under SFC conditions. It was found that an optimal F_feed/F exists which is independent of F and decreases with increasing solvent strength dependency of the sample compound. Decreasing V_ov has a beneficial effect on peak dispersion but can only be varied over a certain range to ensure the full injection of the loaded sample. On the other hand, it was found that a much larger gain could be made by switching the overfeed solvent to one more compatible with the CO₂-based mobile phase. Further reduction of the band broadening could be achieved by applying partial sample injections.

研究了新型SFC喷射器（进料喷射器）的行为。在SFC中，通常将样品化合物稀释在比流动相具有更高洗脱强度的溶剂中，这会导致进样时溶剂失配以及明显的谱带展宽。进样进样器与标准进样器不同，因为进样针或定量环中包含的样品未与流动相流切换，而是直接注入/添加到流动相流（F）中。样品和流动相流的后续混合固有地导致样品稀释，从而减少了溶剂错配。但是，对于给定的进样/进料流速F _feed，包含样品的总体积会增加一个系数（F _feed + F）/ F _feed。另外，为了确保所有加载的样品都注入到色谱柱上，在样品塞之后需要注入额外的过量进料量（V _ov）。为了更好地理解这些操作参数的影响，在SFC条件下，通过改变F_进料/ F比率，V _ov，过量_进料溶剂等，研究了各种注入条件。发现存在最佳的F_进料/ F，其独立于F并且随着样品化合物对溶剂强度的依赖性增加而降低。降低V _ov对峰色散具有有益的影响，但只能在一定范围内变化以确保完全注入加载的样品。另一方面，发现通过将过量进料溶剂切换为与基于CO ₂的流动相更相容的溶剂，可以获得更大的收益。通过应用部分样品进样可以进一步减小谱带展宽。