Numerical investigation of band spreading generated by flow-through needle and fixed loop sample injectors

Numerical and experimental investigation of analyte breakthrough from sampling loops used for multi-dimensional liquid chromatography

“…( 11)). These observations are consistent with the results from Deridder et al [13] who investigated the band broadening during sample injection using a flow-through needle injection for 1D-LC and noted the emergence of the same two dimensionless numbers. In fact, the geometry and assumptions underlying this earlier study are the same as those presented here.…”

“…In 2D-LC, especially in the comprehensive mode of separation (LC×LC), this time is much shorter, and was assumed to be negligible in the simulations described here. In other 2D-LC applications, such as multiple 10 heartcutting, this assumption is of course no longer valid in the cases where there is a significant (>> 1 s) waiting time between the end of filling, and the start of emptying the loop [13]. Consideration of such cases is beyond the scope of this paper.…”

“…Gradients were evaluated using the Least Squares Cell Based method. More detail regarding the numerical models and simulations can be found in previous works [9,13].…”

Extra-column band broadening effects in contemporary liquid chromatography: Causes and solutions

“…In another study, 1/inj=0.8 was found for an injection volume of 0.5µL, although this was determined indirectly [13]. In a follow up study, numerical flow simulations of the injection and elution process of the sample showed that this variation in 1/inj is the combined result of a convective contribution (parabolic flow profile) and a diffusive contribution (radial equilibration) of which the relative contribution changes with changing injection volume [89]. The experimental study also found that V,inj,hydr² is the main source of injector dispersion for small injection volumes, reaching a maximum value of around 1.2µL² or 0.6µL² for a 120µm or 75µm needle seat capillary system at flow rates above 1ml/min [61].…”

Effect of the feed injection method on band broadening in analytical supercritical fluid chromatography

“…V² = Vinj²/12, as the result of the band broadening during sample loading and injection. This was discussed in detail for a flow-through needle type injector in LC in previous experimental work [19] and numerical simulations of the injection process [15]. Figure 8a shows an illustration of the sample plug in the needle at the end of the loading step, based on the simulations performed in [15].…”