The biggest problem in using sandwich injections is that the amount of solvent doubles (assuming that one uses the same volume of solvent as sample). This can aggravate inlet overload, exaggerating loss of volatiles, degrading repeatability, and contaminating cooler areas of the inlet. The larger volume increases time for analytes to transfer from the inlet to the column and increases the probability of peak splitting and distortion when doing splitless injections because of the higher amount of condensed solvent in the column. Clearly, if one were interested in trying sandwich injections, keen attention must be paid to the many associated variables and one should think careful before changing ANYTHING once a suitable set of conditions is found.