With fast autoinjectors, the residence time in the inlet is much less than 500 msec. This is not possible by manual injection. The less time a needle spends in a hot inlet, the less issues one has. So if one uses a fast autoinjector, many of the original reasons to consider sandwich injections are not relevant; yet the potential incremental problems remain or may actually be aggravated. The same holds true with temperature programmable inlets (i.e., PTVs). A major advantage of PTVs is that sample can be introduced at temperatures below the boiling point of the solvent, thereby eliminating needle discrimination and, therefore, the motivation to consider using a chasing solvent.